Dataset Information

granule_type: ATL08
short_name: ATL08
level: 3A
description: This data set (ATL08) contains along-track heights above the WGS84 ellipsoid (ITRF2014 reference frame) for the ground and canopy surfaces. The canopy and ground surfaces are processed in fixed 100 m data segments, which typically contain more than 100 sig
contributor_name: Thomas E Neumann (thomas.neumann@nasa.gov), Thorsten Markus (thorsten.markus@nasa.gov), Suneel Bhardwaj (suneel.bhardwaj@nasa.gov) David W Hancock III (david.w.hancock@nasa.gov)
contributor_role: Instrument Engineer, Investigator, Principle Investigator, Data Producer, Data Producer
Conventions: CF-1.6
date_type: UTC
featureType: trajectory
geospatial_lat_units: degrees_north
geospatial_lon_units: degrees_east
identifier_product_doi: 10.5067/ATLAS/ATL08.001
identifier_product_doi_authority: http://dx.doi.org
identifier_product_type: ATL08
license: Data may not be reproduced or distributed without including the citation for this product included in this metadata. Data may not be distributed in an altered form without the written permission of the ICESat-2 Science Project Office at NASA/GSFC.
naming_authority: http://dx.doi.org
spatial_coverage_type: Horizontal
standard_name_vocabulary: CF-1.6
time_type: CCSDS UTC-A
date_created: 2019-08-22T21:07:29.000000Z
hdfversion: HDF5 1.10.3
history: 2019-08-22T21:07:29.000000Z;58383667-e9b3-3639-a8de-168784ceb5e9;Created by PGE atlas_l3a_ld Version 3.2
identifier_file_uuid: 58383667-e9b3-3639-a8de-168784ceb5e9
identifier_product_format_version: 3.2
time_coverage_duration: 461.00000000000000
time_coverage_end: 2018-10-16T12:54:37.000000Z
time_coverage_start: 2018-10-16T12:46:56.000000Z
geospatial_lat_min: -78.804759009697463
geospatial_lon_min: -153.81953845733065
geospatial_lat_max: -78.498235427544756
geospatial_lon_max: -153.32549412458567
publisher_name: NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center
publisher_email: nsidc@nsidc.org
publisher_url: http://nsidc.org/daac/
title: ATLAS/ICESat-2 L3A Land and Vegetation Height
identifier_file_product_type: ATL08
institution: National Aeronautics and Space Administration (NASA)
creator_name: GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System
summary: The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics.
keywords: EARTH SCIENCE > BIOSPHERE > VEGETATION > NONE > NONE > NONE > NONE
keywords_vocabulary: NASA/GCMD Science Keywords
citation: Cite these data in publications as follows: The data used in this study were produced by the ICESat-2 Science Project Office at NASA/GSFC. The data archive site is the NASA National Snow and Ice Data Center Distributed Active Archive Center.
processing_level: 3A
references: http://nsidc.org/data/icesat2/data.html
project: ICESat-2 > Ice, Cloud, and land Elevation Satellite-2
instrument: ATLAS > Advanced Topographic Laser Altimeter System
platform: ICESat-2 > Ice, Cloud, and land Elevation Satellite-2
source: Spacecraft
Unlimited_Dimension: gt1l_land_segments_delta_time, gt1l_signal_photons_delta_time, gt1r_land_segments_delta_time, gt1r_signal_photons_delta_time, gt2l_signal_photons_delta_time, gt2r_land_segments_delta_time, gt2r_signal_photons_delta_time, gt3l_signal_photons_delta_time, gt3r_land_segments_delta_time, gt3r_signal_photons_delta_time, orbit_info_crossing_time, orbit_info_sc_orient_time


Variables in this Dataset

orbit_info_cycle_number: Array of 16 bit Integers [orbit_info_crossing_time = 0..0]
units: 1
contentType: referenceInformation
long_name: Cycle Number
description: A count of the number of exact repeats of this reference orbit.
source: Operations
valid_min: 0
valid_max: 50
origname: cycle_number
fullnamepath: /orbit_info/cycle_number
coordinates: orbit_info_crossing_time
orbit_info_orbit_number: Array of 16 bit Unsigned integers [orbit_info_crossing_time = 0..0]
units: 1
contentType: referenceInformation
long_name: Orbit Number
description: Unique identifying number for each planned ICESat-2 orbit.
source: Operations
valid_min: 1
valid_max: 65000
origname: orbit_number
fullnamepath: /orbit_info/orbit_number
coordinates: orbit_info_crossing_time
orbit_info_lan: Array of 64 bit Reals [orbit_info_crossing_time = 0..0]
units: degrees_east
contentType: referenceInformation
long_name: Ascending Node Longitude
description: Longitude at the ascending node crossing.
source: POD/PPD
valid_min: -180.00000000000000
valid_max: 180.00000000000000
origname: lan
fullnamepath: /orbit_info/lan
coordinates: orbit_info_crossing_time
orbit_info_sc_orient: Array of 16 bit Integers [orbit_info_sc_orient_time = 0..0]
units: 1
contentType: referenceInformation
long_name: Spacecraft Orientation
description: This parameter tracks the spacecraft orientation between forward, backward and transitional flight modes. ICESat-2 is considered to be flying forward when the weak beams are leading the strong beams; and backward when the strong beams are leading the weak beams. ICESat-2 is considered to be in transition while it is maneuvering between the two orientations. Science quality is potentially degraded while in transition mode.
source: POD/PPD
flag_meanings: backward forward transition
flag_values: 0, 1, 2
valid_min: 0
valid_max: 2
origname: sc_orient
fullnamepath: /orbit_info/sc_orient
coordinates: orbit_info_sc_orient_time
orbit_info_rgt: Array of 16 bit Integers [orbit_info_crossing_time = 0..0]
units: 1
contentType: referenceInformation
long_name: Reference Ground track
description: The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs.
source: POD/PPD
valid_min: 1
valid_max: 1387
origname: rgt
fullnamepath: /orbit_info/rgt
coordinates: orbit_info_crossing_time
gt1r_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt1r_signal_photons_delta_time = 0..69380]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt1r/signal_photons/classed_pc_flag
coordinates: gt1r_signal_photons_delta_time
gt1r_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt1r_signal_photons_delta_time = 0..69380]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt1r/signal_photons/classed_pc_indx
coordinates: gt1r_signal_photons_delta_time
gt1r_signal_photons_d_flag: Array of 16 bit Integers [gt1r_signal_photons_delta_time = 0..69380]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt1r/signal_photons/d_flag
coordinates: gt1r_signal_photons_delta_time
gt1r_signal_photons_ph_segment_id: Array of 32 bit Integers [gt1r_signal_photons_delta_time = 0..69380]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt1r/signal_photons/ph_segment_id
coordinates: gt1r_signal_photons_delta_time
gt1r_land_segments_segment_watermask: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 255
units: 1
long_name: segment watermask
description: Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
source: ATBD section 2.4.15
flag_meanings: no_water water
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: segment_watermask
fullnamepath: /gt1r/land_segments/segment_watermask
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_delta_time_end: Array of 64 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time end
description: Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_end
fullnamepath: /gt1r/land_segments/delta_time_end
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_rgt: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
contentType: referenceInformation
long_name: reference ground track
description: The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs.
source: Operations
valid_min: 1
valid_max: 1387
origname: rgt
fullnamepath: /gt1r/land_segments/rgt
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_dem_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
units: 1
contentType: referenceInformation
long_name: dem source flag
description: Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
source: Atmosphere ATBD
flag_meanings: none arctic gmted mss antarctic
flag_values: 0, 1, 2, 3, 4
valid_min: 0
valid_max: 4
origname: dem_flag
fullnamepath: /gt1r/land_segments/dem_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_msw_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
units: 1
long_name: multiple scattering warning flag
description: Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight.
source: ATL09
flag_meanings: cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5
flag_values: -1, 0, 1, 2, 3, 4, 5
origname: msw_flag
fullnamepath: /gt1r/land_segments/msw_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_cloud_flag_atm: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
units: 1
long_name: cloud flag atm
description: Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10.
source: ATL09
valid_min: 0
valid_max: 10
origname: cloud_flag_atm
fullnamepath: /gt1r/land_segments/cloud_flag_atm
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_snr: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
long_name: signal to noise ratio
description: The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments.
source: ATBD section 2.5.14
origname: snr
fullnamepath: /gt1r/land_segments/snr
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: height canopy
description: 98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_canopy
fullnamepath: /gt1r/land_segments/canopy/h_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_canopy_rh_conf: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
contentType: modelResult
long_name: canopy relative height confidence
description: Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground).
source: Land/Veg ATBD 13March2019, Section 2.2.21
flag_meanings: <5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
flag_values: 0, 1, 2
valid_min: 0
valid_max: 2
origname: canopy_rh_conf
fullnamepath: /gt1r/land_segments/canopy/canopy_rh_conf
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_median_canopy_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment median canopy height
description: The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.6
origname: h_median_canopy_abs
fullnamepath: /gt1r/land_segments/canopy/h_median_canopy_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_min_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum canopy height
description: The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 2.2.10
origname: h_min_canopy
fullnamepath: /gt1r/land_segments/canopy/h_min_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_mean_canopy_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute mean canopy height
description: Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.4
origname: h_mean_canopy_abs
fullnamepath: /gt1r/land_segments/canopy/h_mean_canopy_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_median_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: median canopy height
description: The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature.
source: Land ATBD section 2.2.8
origname: h_median_canopy
fullnamepath: /gt1r/land_segments/canopy/h_median_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_canopy_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment canopy height
description: The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.2
origname: h_canopy_abs
fullnamepath: /gt1r/land_segments/canopy/h_canopy_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_toc_roughness: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: top of canopy roughness
description: Standard deviation of the relative heights of all photons classified as top of canopy within the segment
source: Land ATBD section 4.12
origname: toc_roughness
fullnamepath: /gt1r/land_segments/canopy/toc_roughness
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_min_canopy_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute minimum canopy height
description: The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.9
origname: h_min_canopy_abs
fullnamepath: /gt1r/land_segments/canopy/h_min_canopy_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_dif_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy diff to median height
description: Difference between h_canopy and h_median_canopy
source: Land ATBD section 4.12
origname: h_dif_canopy
fullnamepath: /gt1r/land_segments/canopy/h_dif_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_canopy_quad: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
long_name: canopy quadratic mean
description: The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
source: Land ATBD section 4.12
_FillValue: 3.402823466e+38
units: meters
origname: h_canopy_quad
fullnamepath: /gt1r/land_segments/canopy/h_canopy_quad
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_n_ca_photons: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: number canopy photons
description: The number of photons classified as canopy within the segment.
source: Land ATBD section 4.12
origname: n_ca_photons
fullnamepath: /gt1r/land_segments/canopy/n_ca_photons
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_centroid_height: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: centroid height
description: Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14.
source: Land ATBD section 2.2.22
origname: centroid_height
fullnamepath: /gt1r/land_segments/canopy/centroid_height
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_canopy_h_metrics_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217][ds_metrics = 0..8]
long_name: canopy absolute height metrics
description: Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
_FillValue: 3.402823466e+38
units: meters
origname: canopy_h_metrics_abs
fullnamepath: /gt1r/land_segments/canopy/canopy_h_metrics_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_landsat_perc: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
long_name: landsat percentage canopy
description: Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
source: Land ATBD section 2.2.24
origname: landsat_perc
fullnamepath: /gt1r/land_segments/canopy/landsat_perc
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_mean_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: mean canopy height
description: Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_mean_canopy
fullnamepath: /gt1r/land_segments/canopy/h_mean_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_canopy_h_metrics: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217][ds_metrics = 0..8]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy height metrics
description: Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
origname: canopy_h_metrics
fullnamepath: /gt1r/land_segments/canopy/canopy_h_metrics
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_n_toc_photons: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: number top of canopy photons
description: The number of photons classified as top of canopy within the segment.
source: Land ATBD section 4.12
origname: n_toc_photons
fullnamepath: /gt1r/land_segments/canopy/n_toc_photons
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_canopy_flag: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 2147483647
units: 1
long_name: canopy flag
description: Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present.
source: Land ATBD section 2.2.22
flag_meanings: no_canopy_present canopy_present
flag_values: 0, 1
origname: canopy_flag
fullnamepath: /gt1r/land_segments/canopy/canopy_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_landsat_flag: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 2147483647
units: 1
long_name: landsat flag
description: Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1.
source: Land ATBD section 2.2.25
flag_meanings: canopy_not_assumed_present canopy_assumed_present
flag_values: 0, 1
origname: landsat_flag
fullnamepath: /gt1r/land_segments/canopy/landsat_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_max_canopy_abs: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute maximum canopy height
description: Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.11
origname: h_max_canopy_abs
fullnamepath: /gt1r/land_segments/canopy/h_max_canopy_abs
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_canopy_uncertainty: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: segment canopy height uncertainty
description: Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD
source: Land ATBD section 1.5
origname: h_canopy_uncertainty
fullnamepath: /gt1r/land_segments/canopy/h_canopy_uncertainty
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_canopy_openness: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
long_name: canopy openness
description: Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
source: Land ATBD section 4.12
origname: canopy_openness
fullnamepath: /gt1r/land_segments/canopy/canopy_openness
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_canopy_h_max_canopy: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum canopy height
description: Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature.
source: Land ATBD section 2.2.12
origname: h_max_canopy
fullnamepath: /gt1r/land_segments/canopy/h_max_canopy
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_sigma_across: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas y
description: Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_across
fullnamepath: /gt1r/land_segments/sigma_across
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_uncertainty: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: uncertainty of h_te_mean
description: Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4
source: Land ATBD section 4.11
origname: h_te_uncertainty
fullnamepath: /gt1r/land_segments/terrain/h_te_uncertainty
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_mean: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: mean terrain height
description: The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mean
fullnamepath: /gt1r/land_segments/terrain/h_te_mean
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_min: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum terrain height
description: The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_min
fullnamepath: /gt1r/land_segments/terrain/h_te_min
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_interp: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: interpolated terrain surface height
description: Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
source: Land ATBD section 4.9
origname: h_te_interp
fullnamepath: /gt1r/land_segments/terrain/h_te_interp
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_max: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum terrain height
description: The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_max
fullnamepath: /gt1r/land_segments/terrain/h_te_max
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_skew: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: skew of terrain heights
description: The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_skew
fullnamepath: /gt1r/land_segments/terrain/h_te_skew
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_median: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: median terrain height
description: The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_median
fullnamepath: /gt1r/land_segments/terrain/h_te_median
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_best_fit: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: segment terrain height best fit
description: The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment.
source: Land ATBD section 2.1.15
origname: h_te_best_fit
fullnamepath: /gt1r/land_segments/terrain/h_te_best_fit
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_std: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
long_name: segment terrain roughness
description: The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
_FillValue: 3.402823466e+38
units: meters
origname: h_te_std
fullnamepath: /gt1r/land_segments/terrain/h_te_std
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_terrain_slope: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
long_name: segment terrain slope
description: The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance.
source: Land ATBD section 4.11
origname: terrain_slope
fullnamepath: /gt1r/land_segments/terrain/terrain_slope
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_n_te_photons: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: number of ground photons
description: The number of the photons classified as terrain within the segment.
source: Land ATBD section 4.11
origname: n_te_photons
fullnamepath: /gt1r/land_segments/terrain/n_te_photons
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_h_te_mode: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: mode of terrain heights
description: The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mode
fullnamepath: /gt1r/land_segments/terrain/h_te_mode
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_layer_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
contentType: modelResult
long_name: consolidated cloud flag
description: This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow.
source: ATL09
flag_meanings: likely_clear likely_cloudy
flag_values: 0, 1
origname: layer_flag
fullnamepath: /gt1r/land_segments/layer_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_segment_snowcover: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
units: 1
long_name: segment snowcover
description: Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice.
source: ATBD section 4.2.16
flag_meanings: ice_free_water snow_free_land snow ice
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: segment_snowcover
fullnamepath: /gt1r/land_segments/segment_snowcover
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_beam_azimuth: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam azimuth
description: Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East.
source: ATL03
origname: beam_azimuth
fullnamepath: /gt1r/land_segments/beam_azimuth
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_solar_azimuth: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: degrees_east
contentType: referenceInformation
long_name: solar azimuth
description: The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
source: ATL03g ATBD
origname: solar_azimuth
fullnamepath: /gt1r/land_segments/solar_azimuth
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_psf_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
contentType: referenceInformation
long_name: point spread function flag
description: Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
source: Land/Veg ATBD
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: psf_flag
fullnamepath: /gt1r/land_segments/psf_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_longitude: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: degrees
long_name: longitude
standard_name: longitude
description: Longitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -180.0000000
valid_max: 180.0000000
origname: longitude
fullnamepath: /gt1r/land_segments/longitude
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude
gt1r_land_segments_latitude: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: degrees
long_name: latitude
standard_name: latitude
description: Latitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -90.00000000
valid_max: 90.00000000
origname: latitude
fullnamepath: /gt1r/land_segments/latitude
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_longitude
gt1r_land_segments_segment_id_end: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
contentType: referenceInformation
long_name: end geolocation segment bin
description: Geolocation segment number of the last photon in the land segment.
source: ATL03
origname: segment_id_end
fullnamepath: /gt1r/land_segments/segment_id_end
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_surf_type: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217][ds_surf_type = 0..4]
units: 1
contentType: referenceInformation
long_name: surface type
description: Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water.
source: ATL03 ATBD, Section 4
flag_meanings: not_type is_type
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: surf_type
fullnamepath: /gt1r/land_segments/surf_type
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_brightness_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
units: 1
long_name: brightness flag
description: Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
source: Land ATBD section 2.4.21
flag_meanings: not_bright_surface bright_surface
flag_values: 0, 1
origname: brightness_flag
fullnamepath: /gt1r/land_segments/brightness_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_segment_landcover: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 255
units: 1
long_name: segment landcover
description: IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
source: ATBD section 2.4.14
flag_meanings: Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren
flag_values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
valid_min: 0
valid_max: 16
origname: segment_landcover
fullnamepath: /gt1r/land_segments/segment_landcover
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_ph_removal_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: ph removal flag
description: Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
source: ATBD section 4.13
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: ph_removal_flag
fullnamepath: /gt1r/land_segments/ph_removal_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_asr: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
long_name: apparent surface reflectance
description: Apparent surface reflectance
source: ATL09
origname: asr
fullnamepath: /gt1r/land_segments/asr
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_sigma_atlas_land: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas land
description: Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
source: Land ATBD section 2.5.13
origname: sigma_atlas_land
fullnamepath: /gt1r/land_segments/sigma_atlas_land
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_segment_id_beg: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
contentType: referenceInformation
long_name: begin geolocation segment bin
description: Geolocation segment number of the first photon in the land segment.
source: ATL03
origname: segment_id_beg
fullnamepath: /gt1r/land_segments/segment_id_beg
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_sigma_along: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas x
description: Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_along
fullnamepath: /gt1r/land_segments/sigma_along
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_dem_h: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
contentType: referenceInformation
long_name: dem height
description: Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
source: GIMP, GMTED,MSS
origname: dem_h
fullnamepath: /gt1r/land_segments/dem_h
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_beam_coelev: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam co-elevation
description: Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
source: ATL03
origname: beam_coelev
fullnamepath: /gt1r/land_segments/beam_coelev
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_sigma_topo: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas topo
description: Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope.
source: Land ATBD section 2.5.12
origname: sigma_topo
fullnamepath: /gt1r/land_segments/sigma_topo
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_night_flag: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 2147483647
units: 1
long_name: night flag
description: Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod.
source: Land ATBD section 2.4.8
flag_meanings: day night
flag_values: 0, 1
origname: night_flag
fullnamepath: /gt1r/land_segments/night_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_delta_time_beg: Array of 64 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time begin
description: Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_beg
fullnamepath: /gt1r/land_segments/delta_time_beg
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_sigma_h: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
contentType: referenceInformation
long_name: height uncertainty
description: Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
_FillValue: 3.402823466e+38
units: 1
origname: sigma_h
fullnamepath: /gt1r/land_segments/sigma_h
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_last_seg_extend: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: kilometers
long_name: last segment extended
standard_name: last_seg_extend
description: The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
source: Land ATBD 13March2019, Section 2.4.20
origname: last_seg_extend
fullnamepath: /gt1r/land_segments/last_seg_extend
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_atlas_pa: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: atlas pointing angle
description: Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
source: ATL03
origname: atlas_pa
fullnamepath: /gt1r/land_segments/atlas_pa
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_solar_elevation: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: degrees
contentType: referenceInformation
long_name: solar elevation
description: Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy.
source: ATL03g ATBD
origname: solar_elevation
fullnamepath: /gt1r/land_segments/solar_elevation
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_cloud_fold_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 127
contentType: modelResult
long_name: cloud folding flag
description: Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings.
source: ATL09
flag_meanings: no_folding goes5_indicates profile_indicates both_indicate
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: cloud_fold_flag
fullnamepath: /gt1r/land_segments/cloud_fold_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_n_seg_ph: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: number of photons
description: Number of photons within each land segment.
source: Derived
origname: n_seg_ph
fullnamepath: /gt1r/land_segments/n_seg_ph
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_terrain_flg: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 2147483647
units: 1
long_name: terrain flag
description: Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
source: Land ATBD section 2.4.8
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: terrain_flg
fullnamepath: /gt1r/land_segments/terrain_flg
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_urban_flag: Array of 32 bit Integers [gt1r_land_segments_delta_time = 0..217]
_FillValue: 2147483647
units: 1
long_name: segment urban flag
description: The urban flag indicates that a segment is likely located over an urban area.
source: Land ATBD section 2.4.17
flag_meanings: not_urban urban
flag_values: 0, 1
origname: urban_flag
fullnamepath: /gt1r/land_segments/urban_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_dem_removal_flag: Array of 16 bit Integers [gt1r_land_segments_delta_time = 0..217]
units: 1
long_name: dem removal flag
description: Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
source: ATBD section 2.4.11
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: dem_removal_flag
fullnamepath: /gt1r/land_segments/dem_removal_flag
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt1r_land_segments_h_dif_ref: Array of 32 bit Reals [gt1r_land_segments_delta_time = 0..217]
_FillValue: 3.402823466e+38
units: meters
long_name: h dif from reference
description: Difference between h_te_median and ref_DEM
source: Land ATBD section 2.4
origname: h_dif_ref
fullnamepath: /gt1r/land_segments/h_dif_ref
coordinates: gt1r_land_segments_delta_time gt1r_land_segments_latitude gt1r_land_segments_longitude
gt2r_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt2r_signal_photons_delta_time = 0..14712]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt2r/signal_photons/classed_pc_flag
coordinates: gt2r_signal_photons_delta_time
gt2r_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt2r_signal_photons_delta_time = 0..14712]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt2r/signal_photons/classed_pc_indx
coordinates: gt2r_signal_photons_delta_time
gt2r_signal_photons_d_flag: Array of 16 bit Integers [gt2r_signal_photons_delta_time = 0..14712]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt2r/signal_photons/d_flag
coordinates: gt2r_signal_photons_delta_time
gt2r_signal_photons_ph_segment_id: Array of 32 bit Integers [gt2r_signal_photons_delta_time = 0..14712]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt2r/signal_photons/ph_segment_id
coordinates: gt2r_signal_photons_delta_time
gt2r_land_segments_segment_watermask: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 255
units: 1
long_name: segment watermask
description: Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
source: ATBD section 2.4.15
flag_meanings: no_water water
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: segment_watermask
fullnamepath: /gt2r/land_segments/segment_watermask
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_delta_time_end: Array of 64 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time end
description: Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_end
fullnamepath: /gt2r/land_segments/delta_time_end
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_rgt: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
contentType: referenceInformation
long_name: reference ground track
description: The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs.
source: Operations
valid_min: 1
valid_max: 1387
origname: rgt
fullnamepath: /gt2r/land_segments/rgt
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_dem_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
units: 1
contentType: referenceInformation
long_name: dem source flag
description: Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
source: Atmosphere ATBD
flag_meanings: none arctic gmted mss antarctic
flag_values: 0, 1, 2, 3, 4
valid_min: 0
valid_max: 4
origname: dem_flag
fullnamepath: /gt2r/land_segments/dem_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_msw_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
units: 1
long_name: multiple scattering warning flag
description: Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight.
source: ATL09
flag_meanings: cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5
flag_values: -1, 0, 1, 2, 3, 4, 5
origname: msw_flag
fullnamepath: /gt2r/land_segments/msw_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_cloud_flag_atm: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
units: 1
long_name: cloud flag atm
description: Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10.
source: ATL09
valid_min: 0
valid_max: 10
origname: cloud_flag_atm
fullnamepath: /gt2r/land_segments/cloud_flag_atm
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_snr: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
long_name: signal to noise ratio
description: The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments.
source: ATBD section 2.5.14
origname: snr
fullnamepath: /gt2r/land_segments/snr
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: height canopy
description: 98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_canopy
fullnamepath: /gt2r/land_segments/canopy/h_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_canopy_rh_conf: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
contentType: modelResult
long_name: canopy relative height confidence
description: Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground).
source: Land/Veg ATBD 13March2019, Section 2.2.21
flag_meanings: <5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
flag_values: 0, 1, 2
valid_min: 0
valid_max: 2
origname: canopy_rh_conf
fullnamepath: /gt2r/land_segments/canopy/canopy_rh_conf
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_median_canopy_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment median canopy height
description: The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.6
origname: h_median_canopy_abs
fullnamepath: /gt2r/land_segments/canopy/h_median_canopy_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_min_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum canopy height
description: The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 2.2.10
origname: h_min_canopy
fullnamepath: /gt2r/land_segments/canopy/h_min_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_mean_canopy_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute mean canopy height
description: Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.4
origname: h_mean_canopy_abs
fullnamepath: /gt2r/land_segments/canopy/h_mean_canopy_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_median_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: median canopy height
description: The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature.
source: Land ATBD section 2.2.8
origname: h_median_canopy
fullnamepath: /gt2r/land_segments/canopy/h_median_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_canopy_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment canopy height
description: The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.2
origname: h_canopy_abs
fullnamepath: /gt2r/land_segments/canopy/h_canopy_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_toc_roughness: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: top of canopy roughness
description: Standard deviation of the relative heights of all photons classified as top of canopy within the segment
source: Land ATBD section 4.12
origname: toc_roughness
fullnamepath: /gt2r/land_segments/canopy/toc_roughness
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_min_canopy_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute minimum canopy height
description: The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.9
origname: h_min_canopy_abs
fullnamepath: /gt2r/land_segments/canopy/h_min_canopy_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_dif_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy diff to median height
description: Difference between h_canopy and h_median_canopy
source: Land ATBD section 4.12
origname: h_dif_canopy
fullnamepath: /gt2r/land_segments/canopy/h_dif_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_canopy_quad: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
long_name: canopy quadratic mean
description: The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
source: Land ATBD section 4.12
_FillValue: 3.402823466e+38
units: meters
origname: h_canopy_quad
fullnamepath: /gt2r/land_segments/canopy/h_canopy_quad
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_n_ca_photons: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: number canopy photons
description: The number of photons classified as canopy within the segment.
source: Land ATBD section 4.12
origname: n_ca_photons
fullnamepath: /gt2r/land_segments/canopy/n_ca_photons
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_centroid_height: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: centroid height
description: Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14.
source: Land ATBD section 2.2.22
origname: centroid_height
fullnamepath: /gt2r/land_segments/canopy/centroid_height
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_canopy_h_metrics_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77][ds_metrics = 0..8]
long_name: canopy absolute height metrics
description: Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
_FillValue: 3.402823466e+38
units: meters
origname: canopy_h_metrics_abs
fullnamepath: /gt2r/land_segments/canopy/canopy_h_metrics_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_landsat_perc: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
long_name: landsat percentage canopy
description: Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
source: Land ATBD section 2.2.24
origname: landsat_perc
fullnamepath: /gt2r/land_segments/canopy/landsat_perc
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_mean_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: mean canopy height
description: Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_mean_canopy
fullnamepath: /gt2r/land_segments/canopy/h_mean_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_canopy_h_metrics: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77][ds_metrics = 0..8]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy height metrics
description: Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
origname: canopy_h_metrics
fullnamepath: /gt2r/land_segments/canopy/canopy_h_metrics
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_n_toc_photons: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: number top of canopy photons
description: The number of photons classified as top of canopy within the segment.
source: Land ATBD section 4.12
origname: n_toc_photons
fullnamepath: /gt2r/land_segments/canopy/n_toc_photons
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_canopy_flag: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 2147483647
units: 1
long_name: canopy flag
description: Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present.
source: Land ATBD section 2.2.22
flag_meanings: no_canopy_present canopy_present
flag_values: 0, 1
origname: canopy_flag
fullnamepath: /gt2r/land_segments/canopy/canopy_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_landsat_flag: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 2147483647
units: 1
long_name: landsat flag
description: Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1.
source: Land ATBD section 2.2.25
flag_meanings: canopy_not_assumed_present canopy_assumed_present
flag_values: 0, 1
origname: landsat_flag
fullnamepath: /gt2r/land_segments/canopy/landsat_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_max_canopy_abs: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute maximum canopy height
description: Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.11
origname: h_max_canopy_abs
fullnamepath: /gt2r/land_segments/canopy/h_max_canopy_abs
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_canopy_uncertainty: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: segment canopy height uncertainty
description: Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD
source: Land ATBD section 1.5
origname: h_canopy_uncertainty
fullnamepath: /gt2r/land_segments/canopy/h_canopy_uncertainty
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_canopy_openness: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
long_name: canopy openness
description: Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
source: Land ATBD section 4.12
origname: canopy_openness
fullnamepath: /gt2r/land_segments/canopy/canopy_openness
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_canopy_h_max_canopy: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum canopy height
description: Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature.
source: Land ATBD section 2.2.12
origname: h_max_canopy
fullnamepath: /gt2r/land_segments/canopy/h_max_canopy
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_sigma_across: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas y
description: Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_across
fullnamepath: /gt2r/land_segments/sigma_across
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_uncertainty: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: uncertainty of h_te_mean
description: Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4
source: Land ATBD section 4.11
origname: h_te_uncertainty
fullnamepath: /gt2r/land_segments/terrain/h_te_uncertainty
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_mean: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: mean terrain height
description: The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mean
fullnamepath: /gt2r/land_segments/terrain/h_te_mean
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_min: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum terrain height
description: The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_min
fullnamepath: /gt2r/land_segments/terrain/h_te_min
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_interp: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: interpolated terrain surface height
description: Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
source: Land ATBD section 4.9
origname: h_te_interp
fullnamepath: /gt2r/land_segments/terrain/h_te_interp
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_max: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum terrain height
description: The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_max
fullnamepath: /gt2r/land_segments/terrain/h_te_max
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_skew: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: skew of terrain heights
description: The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_skew
fullnamepath: /gt2r/land_segments/terrain/h_te_skew
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_median: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: median terrain height
description: The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_median
fullnamepath: /gt2r/land_segments/terrain/h_te_median
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_best_fit: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: segment terrain height best fit
description: The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment.
source: Land ATBD section 2.1.15
origname: h_te_best_fit
fullnamepath: /gt2r/land_segments/terrain/h_te_best_fit
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_std: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
long_name: segment terrain roughness
description: The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
_FillValue: 3.402823466e+38
units: meters
origname: h_te_std
fullnamepath: /gt2r/land_segments/terrain/h_te_std
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_terrain_slope: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
long_name: segment terrain slope
description: The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance.
source: Land ATBD section 4.11
origname: terrain_slope
fullnamepath: /gt2r/land_segments/terrain/terrain_slope
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_n_te_photons: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: number of ground photons
description: The number of the photons classified as terrain within the segment.
source: Land ATBD section 4.11
origname: n_te_photons
fullnamepath: /gt2r/land_segments/terrain/n_te_photons
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_h_te_mode: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: mode of terrain heights
description: The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mode
fullnamepath: /gt2r/land_segments/terrain/h_te_mode
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_layer_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
contentType: modelResult
long_name: consolidated cloud flag
description: This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow.
source: ATL09
flag_meanings: likely_clear likely_cloudy
flag_values: 0, 1
origname: layer_flag
fullnamepath: /gt2r/land_segments/layer_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_segment_snowcover: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
units: 1
long_name: segment snowcover
description: Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice.
source: ATBD section 4.2.16
flag_meanings: ice_free_water snow_free_land snow ice
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: segment_snowcover
fullnamepath: /gt2r/land_segments/segment_snowcover
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_beam_azimuth: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam azimuth
description: Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East.
source: ATL03
origname: beam_azimuth
fullnamepath: /gt2r/land_segments/beam_azimuth
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_solar_azimuth: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: degrees_east
contentType: referenceInformation
long_name: solar azimuth
description: The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
source: ATL03g ATBD
origname: solar_azimuth
fullnamepath: /gt2r/land_segments/solar_azimuth
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_psf_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
contentType: referenceInformation
long_name: point spread function flag
description: Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
source: Land/Veg ATBD
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: psf_flag
fullnamepath: /gt2r/land_segments/psf_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_longitude: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: degrees
long_name: longitude
standard_name: longitude
description: Longitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -180.0000000
valid_max: 180.0000000
origname: longitude
fullnamepath: /gt2r/land_segments/longitude
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude
gt2r_land_segments_latitude: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: degrees
long_name: latitude
standard_name: latitude
description: Latitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -90.00000000
valid_max: 90.00000000
origname: latitude
fullnamepath: /gt2r/land_segments/latitude
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_longitude
gt2r_land_segments_segment_id_end: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
contentType: referenceInformation
long_name: end geolocation segment bin
description: Geolocation segment number of the last photon in the land segment.
source: ATL03
origname: segment_id_end
fullnamepath: /gt2r/land_segments/segment_id_end
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_surf_type: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77][ds_surf_type = 0..4]
units: 1
contentType: referenceInformation
long_name: surface type
description: Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water.
source: ATL03 ATBD, Section 4
flag_meanings: not_type is_type
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: surf_type
fullnamepath: /gt2r/land_segments/surf_type
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_brightness_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
units: 1
long_name: brightness flag
description: Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
source: Land ATBD section 2.4.21
flag_meanings: not_bright_surface bright_surface
flag_values: 0, 1
origname: brightness_flag
fullnamepath: /gt2r/land_segments/brightness_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_segment_landcover: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 255
units: 1
long_name: segment landcover
description: IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
source: ATBD section 2.4.14
flag_meanings: Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren
flag_values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
valid_min: 0
valid_max: 16
origname: segment_landcover
fullnamepath: /gt2r/land_segments/segment_landcover
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_ph_removal_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: ph removal flag
description: Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
source: ATBD section 4.13
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: ph_removal_flag
fullnamepath: /gt2r/land_segments/ph_removal_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_asr: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
long_name: apparent surface reflectance
description: Apparent surface reflectance
source: ATL09
origname: asr
fullnamepath: /gt2r/land_segments/asr
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_sigma_atlas_land: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas land
description: Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
source: Land ATBD section 2.5.13
origname: sigma_atlas_land
fullnamepath: /gt2r/land_segments/sigma_atlas_land
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_segment_id_beg: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
contentType: referenceInformation
long_name: begin geolocation segment bin
description: Geolocation segment number of the first photon in the land segment.
source: ATL03
origname: segment_id_beg
fullnamepath: /gt2r/land_segments/segment_id_beg
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_sigma_along: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas x
description: Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_along
fullnamepath: /gt2r/land_segments/sigma_along
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_dem_h: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
contentType: referenceInformation
long_name: dem height
description: Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
source: GIMP, GMTED,MSS
origname: dem_h
fullnamepath: /gt2r/land_segments/dem_h
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_beam_coelev: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam co-elevation
description: Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
source: ATL03
origname: beam_coelev
fullnamepath: /gt2r/land_segments/beam_coelev
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_sigma_topo: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas topo
description: Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope.
source: Land ATBD section 2.5.12
origname: sigma_topo
fullnamepath: /gt2r/land_segments/sigma_topo
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_night_flag: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 2147483647
units: 1
long_name: night flag
description: Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod.
source: Land ATBD section 2.4.8
flag_meanings: day night
flag_values: 0, 1
origname: night_flag
fullnamepath: /gt2r/land_segments/night_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_delta_time_beg: Array of 64 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time begin
description: Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_beg
fullnamepath: /gt2r/land_segments/delta_time_beg
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_sigma_h: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
contentType: referenceInformation
long_name: height uncertainty
description: Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
_FillValue: 3.402823466e+38
units: 1
origname: sigma_h
fullnamepath: /gt2r/land_segments/sigma_h
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_last_seg_extend: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: kilometers
long_name: last segment extended
standard_name: last_seg_extend
description: The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
source: Land ATBD 13March2019, Section 2.4.20
origname: last_seg_extend
fullnamepath: /gt2r/land_segments/last_seg_extend
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_atlas_pa: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: atlas pointing angle
description: Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
source: ATL03
origname: atlas_pa
fullnamepath: /gt2r/land_segments/atlas_pa
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_solar_elevation: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: degrees
contentType: referenceInformation
long_name: solar elevation
description: Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy.
source: ATL03g ATBD
origname: solar_elevation
fullnamepath: /gt2r/land_segments/solar_elevation
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_cloud_fold_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 127
contentType: modelResult
long_name: cloud folding flag
description: Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings.
source: ATL09
flag_meanings: no_folding goes5_indicates profile_indicates both_indicate
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: cloud_fold_flag
fullnamepath: /gt2r/land_segments/cloud_fold_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_n_seg_ph: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: number of photons
description: Number of photons within each land segment.
source: Derived
origname: n_seg_ph
fullnamepath: /gt2r/land_segments/n_seg_ph
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_terrain_flg: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 2147483647
units: 1
long_name: terrain flag
description: Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
source: Land ATBD section 2.4.8
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: terrain_flg
fullnamepath: /gt2r/land_segments/terrain_flg
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_urban_flag: Array of 32 bit Integers [gt2r_land_segments_delta_time = 0..77]
_FillValue: 2147483647
units: 1
long_name: segment urban flag
description: The urban flag indicates that a segment is likely located over an urban area.
source: Land ATBD section 2.4.17
flag_meanings: not_urban urban
flag_values: 0, 1
origname: urban_flag
fullnamepath: /gt2r/land_segments/urban_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_dem_removal_flag: Array of 16 bit Integers [gt2r_land_segments_delta_time = 0..77]
units: 1
long_name: dem removal flag
description: Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
source: ATBD section 2.4.11
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: dem_removal_flag
fullnamepath: /gt2r/land_segments/dem_removal_flag
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt2r_land_segments_h_dif_ref: Array of 32 bit Reals [gt2r_land_segments_delta_time = 0..77]
_FillValue: 3.402823466e+38
units: meters
long_name: h dif from reference
description: Difference between h_te_median and ref_DEM
source: Land ATBD section 2.4
origname: h_dif_ref
fullnamepath: /gt2r/land_segments/h_dif_ref
coordinates: gt2r_land_segments_delta_time gt2r_land_segments_latitude gt2r_land_segments_longitude
gt1l_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt1l_signal_photons_delta_time = 0..17464]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt1l/signal_photons/classed_pc_flag
coordinates: gt1l_signal_photons_delta_time
gt1l_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt1l_signal_photons_delta_time = 0..17464]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt1l/signal_photons/classed_pc_indx
coordinates: gt1l_signal_photons_delta_time
gt1l_signal_photons_d_flag: Array of 16 bit Integers [gt1l_signal_photons_delta_time = 0..17464]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt1l/signal_photons/d_flag
coordinates: gt1l_signal_photons_delta_time
gt1l_signal_photons_ph_segment_id: Array of 32 bit Integers [gt1l_signal_photons_delta_time = 0..17464]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt1l/signal_photons/ph_segment_id
coordinates: gt1l_signal_photons_delta_time
gt1l_land_segments_segment_watermask: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 255
units: 1
long_name: segment watermask
description: Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
source: ATBD section 2.4.15
flag_meanings: no_water water
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: segment_watermask
fullnamepath: /gt1l/land_segments/segment_watermask
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_delta_time_end: Array of 64 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time end
description: Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_end
fullnamepath: /gt1l/land_segments/delta_time_end
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_rgt: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
contentType: referenceInformation
long_name: reference ground track
description: The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs.
source: Operations
valid_min: 1
valid_max: 1387
origname: rgt
fullnamepath: /gt1l/land_segments/rgt
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_dem_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
units: 1
contentType: referenceInformation
long_name: dem source flag
description: Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
source: Atmosphere ATBD
flag_meanings: none arctic gmted mss antarctic
flag_values: 0, 1, 2, 3, 4
valid_min: 0
valid_max: 4
origname: dem_flag
fullnamepath: /gt1l/land_segments/dem_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_msw_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
units: 1
long_name: multiple scattering warning flag
description: Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight.
source: ATL09
flag_meanings: cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5
flag_values: -1, 0, 1, 2, 3, 4, 5
origname: msw_flag
fullnamepath: /gt1l/land_segments/msw_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_cloud_flag_atm: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
units: 1
long_name: cloud flag atm
description: Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10.
source: ATL09
valid_min: 0
valid_max: 10
origname: cloud_flag_atm
fullnamepath: /gt1l/land_segments/cloud_flag_atm
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_snr: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
long_name: signal to noise ratio
description: The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments.
source: ATBD section 2.5.14
origname: snr
fullnamepath: /gt1l/land_segments/snr
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: height canopy
description: 98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_canopy
fullnamepath: /gt1l/land_segments/canopy/h_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_canopy_rh_conf: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
contentType: modelResult
long_name: canopy relative height confidence
description: Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground).
source: Land/Veg ATBD 13March2019, Section 2.2.21
flag_meanings: <5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
flag_values: 0, 1, 2
valid_min: 0
valid_max: 2
origname: canopy_rh_conf
fullnamepath: /gt1l/land_segments/canopy/canopy_rh_conf
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_median_canopy_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment median canopy height
description: The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.6
origname: h_median_canopy_abs
fullnamepath: /gt1l/land_segments/canopy/h_median_canopy_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_min_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum canopy height
description: The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 2.2.10
origname: h_min_canopy
fullnamepath: /gt1l/land_segments/canopy/h_min_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_mean_canopy_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute mean canopy height
description: Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.4
origname: h_mean_canopy_abs
fullnamepath: /gt1l/land_segments/canopy/h_mean_canopy_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_median_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: median canopy height
description: The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature.
source: Land ATBD section 2.2.8
origname: h_median_canopy
fullnamepath: /gt1l/land_segments/canopy/h_median_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_canopy_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment canopy height
description: The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.2
origname: h_canopy_abs
fullnamepath: /gt1l/land_segments/canopy/h_canopy_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_toc_roughness: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: top of canopy roughness
description: Standard deviation of the relative heights of all photons classified as top of canopy within the segment
source: Land ATBD section 4.12
origname: toc_roughness
fullnamepath: /gt1l/land_segments/canopy/toc_roughness
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_min_canopy_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute minimum canopy height
description: The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.9
origname: h_min_canopy_abs
fullnamepath: /gt1l/land_segments/canopy/h_min_canopy_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_dif_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy diff to median height
description: Difference between h_canopy and h_median_canopy
source: Land ATBD section 4.12
origname: h_dif_canopy
fullnamepath: /gt1l/land_segments/canopy/h_dif_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_canopy_quad: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
long_name: canopy quadratic mean
description: The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
source: Land ATBD section 4.12
_FillValue: 3.402823466e+38
units: meters
origname: h_canopy_quad
fullnamepath: /gt1l/land_segments/canopy/h_canopy_quad
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_n_ca_photons: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: number canopy photons
description: The number of photons classified as canopy within the segment.
source: Land ATBD section 4.12
origname: n_ca_photons
fullnamepath: /gt1l/land_segments/canopy/n_ca_photons
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_centroid_height: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: centroid height
description: Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14.
source: Land ATBD section 2.2.22
origname: centroid_height
fullnamepath: /gt1l/land_segments/canopy/centroid_height
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_canopy_h_metrics_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133][ds_metrics = 0..8]
long_name: canopy absolute height metrics
description: Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
_FillValue: 3.402823466e+38
units: meters
origname: canopy_h_metrics_abs
fullnamepath: /gt1l/land_segments/canopy/canopy_h_metrics_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_landsat_perc: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
long_name: landsat percentage canopy
description: Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
source: Land ATBD section 2.2.24
origname: landsat_perc
fullnamepath: /gt1l/land_segments/canopy/landsat_perc
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_mean_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: mean canopy height
description: Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_mean_canopy
fullnamepath: /gt1l/land_segments/canopy/h_mean_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_canopy_h_metrics: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133][ds_metrics = 0..8]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy height metrics
description: Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
origname: canopy_h_metrics
fullnamepath: /gt1l/land_segments/canopy/canopy_h_metrics
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_n_toc_photons: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: number top of canopy photons
description: The number of photons classified as top of canopy within the segment.
source: Land ATBD section 4.12
origname: n_toc_photons
fullnamepath: /gt1l/land_segments/canopy/n_toc_photons
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_canopy_flag: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 2147483647
units: 1
long_name: canopy flag
description: Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present.
source: Land ATBD section 2.2.22
flag_meanings: no_canopy_present canopy_present
flag_values: 0, 1
origname: canopy_flag
fullnamepath: /gt1l/land_segments/canopy/canopy_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_landsat_flag: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 2147483647
units: 1
long_name: landsat flag
description: Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1.
source: Land ATBD section 2.2.25
flag_meanings: canopy_not_assumed_present canopy_assumed_present
flag_values: 0, 1
origname: landsat_flag
fullnamepath: /gt1l/land_segments/canopy/landsat_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_max_canopy_abs: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute maximum canopy height
description: Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.11
origname: h_max_canopy_abs
fullnamepath: /gt1l/land_segments/canopy/h_max_canopy_abs
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_canopy_uncertainty: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: segment canopy height uncertainty
description: Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD
source: Land ATBD section 1.5
origname: h_canopy_uncertainty
fullnamepath: /gt1l/land_segments/canopy/h_canopy_uncertainty
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_canopy_openness: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
long_name: canopy openness
description: Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
source: Land ATBD section 4.12
origname: canopy_openness
fullnamepath: /gt1l/land_segments/canopy/canopy_openness
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_canopy_h_max_canopy: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum canopy height
description: Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature.
source: Land ATBD section 2.2.12
origname: h_max_canopy
fullnamepath: /gt1l/land_segments/canopy/h_max_canopy
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_sigma_across: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas y
description: Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_across
fullnamepath: /gt1l/land_segments/sigma_across
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_uncertainty: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: uncertainty of h_te_mean
description: Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4
source: Land ATBD section 4.11
origname: h_te_uncertainty
fullnamepath: /gt1l/land_segments/terrain/h_te_uncertainty
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_mean: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: mean terrain height
description: The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mean
fullnamepath: /gt1l/land_segments/terrain/h_te_mean
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_min: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum terrain height
description: The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_min
fullnamepath: /gt1l/land_segments/terrain/h_te_min
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_interp: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: interpolated terrain surface height
description: Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
source: Land ATBD section 4.9
origname: h_te_interp
fullnamepath: /gt1l/land_segments/terrain/h_te_interp
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_max: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum terrain height
description: The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_max
fullnamepath: /gt1l/land_segments/terrain/h_te_max
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_skew: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: skew of terrain heights
description: The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_skew
fullnamepath: /gt1l/land_segments/terrain/h_te_skew
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_median: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: median terrain height
description: The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_median
fullnamepath: /gt1l/land_segments/terrain/h_te_median
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_best_fit: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: segment terrain height best fit
description: The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment.
source: Land ATBD section 2.1.15
origname: h_te_best_fit
fullnamepath: /gt1l/land_segments/terrain/h_te_best_fit
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_std: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
long_name: segment terrain roughness
description: The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
_FillValue: 3.402823466e+38
units: meters
origname: h_te_std
fullnamepath: /gt1l/land_segments/terrain/h_te_std
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_terrain_slope: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
long_name: segment terrain slope
description: The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance.
source: Land ATBD section 4.11
origname: terrain_slope
fullnamepath: /gt1l/land_segments/terrain/terrain_slope
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_n_te_photons: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: number of ground photons
description: The number of the photons classified as terrain within the segment.
source: Land ATBD section 4.11
origname: n_te_photons
fullnamepath: /gt1l/land_segments/terrain/n_te_photons
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_h_te_mode: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: mode of terrain heights
description: The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mode
fullnamepath: /gt1l/land_segments/terrain/h_te_mode
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_layer_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
contentType: modelResult
long_name: consolidated cloud flag
description: This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow.
source: ATL09
flag_meanings: likely_clear likely_cloudy
flag_values: 0, 1
origname: layer_flag
fullnamepath: /gt1l/land_segments/layer_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_segment_snowcover: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
units: 1
long_name: segment snowcover
description: Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice.
source: ATBD section 4.2.16
flag_meanings: ice_free_water snow_free_land snow ice
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: segment_snowcover
fullnamepath: /gt1l/land_segments/segment_snowcover
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_beam_azimuth: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam azimuth
description: Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East.
source: ATL03
origname: beam_azimuth
fullnamepath: /gt1l/land_segments/beam_azimuth
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_solar_azimuth: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: degrees_east
contentType: referenceInformation
long_name: solar azimuth
description: The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
source: ATL03g ATBD
origname: solar_azimuth
fullnamepath: /gt1l/land_segments/solar_azimuth
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_psf_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
contentType: referenceInformation
long_name: point spread function flag
description: Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
source: Land/Veg ATBD
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: psf_flag
fullnamepath: /gt1l/land_segments/psf_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_longitude: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: degrees
long_name: longitude
standard_name: longitude
description: Longitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -180.0000000
valid_max: 180.0000000
origname: longitude
fullnamepath: /gt1l/land_segments/longitude
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude
gt1l_land_segments_latitude: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: degrees
long_name: latitude
standard_name: latitude
description: Latitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -90.00000000
valid_max: 90.00000000
origname: latitude
fullnamepath: /gt1l/land_segments/latitude
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_longitude
gt1l_land_segments_segment_id_end: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
contentType: referenceInformation
long_name: end geolocation segment bin
description: Geolocation segment number of the last photon in the land segment.
source: ATL03
origname: segment_id_end
fullnamepath: /gt1l/land_segments/segment_id_end
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_surf_type: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133][ds_surf_type = 0..4]
units: 1
contentType: referenceInformation
long_name: surface type
description: Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water.
source: ATL03 ATBD, Section 4
flag_meanings: not_type is_type
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: surf_type
fullnamepath: /gt1l/land_segments/surf_type
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_brightness_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
units: 1
long_name: brightness flag
description: Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
source: Land ATBD section 2.4.21
flag_meanings: not_bright_surface bright_surface
flag_values: 0, 1
origname: brightness_flag
fullnamepath: /gt1l/land_segments/brightness_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_segment_landcover: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 255
units: 1
long_name: segment landcover
description: IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
source: ATBD section 2.4.14
flag_meanings: Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren
flag_values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
valid_min: 0
valid_max: 16
origname: segment_landcover
fullnamepath: /gt1l/land_segments/segment_landcover
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_ph_removal_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: ph removal flag
description: Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
source: ATBD section 4.13
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: ph_removal_flag
fullnamepath: /gt1l/land_segments/ph_removal_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_asr: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
long_name: apparent surface reflectance
description: Apparent surface reflectance
source: ATL09
origname: asr
fullnamepath: /gt1l/land_segments/asr
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_sigma_atlas_land: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas land
description: Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
source: Land ATBD section 2.5.13
origname: sigma_atlas_land
fullnamepath: /gt1l/land_segments/sigma_atlas_land
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_segment_id_beg: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
contentType: referenceInformation
long_name: begin geolocation segment bin
description: Geolocation segment number of the first photon in the land segment.
source: ATL03
origname: segment_id_beg
fullnamepath: /gt1l/land_segments/segment_id_beg
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_sigma_along: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas x
description: Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_along
fullnamepath: /gt1l/land_segments/sigma_along
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_dem_h: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
contentType: referenceInformation
long_name: dem height
description: Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
source: GIMP, GMTED,MSS
origname: dem_h
fullnamepath: /gt1l/land_segments/dem_h
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_beam_coelev: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam co-elevation
description: Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
source: ATL03
origname: beam_coelev
fullnamepath: /gt1l/land_segments/beam_coelev
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_sigma_topo: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas topo
description: Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope.
source: Land ATBD section 2.5.12
origname: sigma_topo
fullnamepath: /gt1l/land_segments/sigma_topo
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_night_flag: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 2147483647
units: 1
long_name: night flag
description: Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod.
source: Land ATBD section 2.4.8
flag_meanings: day night
flag_values: 0, 1
origname: night_flag
fullnamepath: /gt1l/land_segments/night_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_delta_time_beg: Array of 64 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time begin
description: Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_beg
fullnamepath: /gt1l/land_segments/delta_time_beg
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_sigma_h: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
contentType: referenceInformation
long_name: height uncertainty
description: Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
_FillValue: 3.402823466e+38
units: 1
origname: sigma_h
fullnamepath: /gt1l/land_segments/sigma_h
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_last_seg_extend: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: kilometers
long_name: last segment extended
standard_name: last_seg_extend
description: The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
source: Land ATBD 13March2019, Section 2.4.20
origname: last_seg_extend
fullnamepath: /gt1l/land_segments/last_seg_extend
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_atlas_pa: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: atlas pointing angle
description: Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
source: ATL03
origname: atlas_pa
fullnamepath: /gt1l/land_segments/atlas_pa
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_solar_elevation: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: degrees
contentType: referenceInformation
long_name: solar elevation
description: Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy.
source: ATL03g ATBD
origname: solar_elevation
fullnamepath: /gt1l/land_segments/solar_elevation
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_cloud_fold_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 127
contentType: modelResult
long_name: cloud folding flag
description: Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings.
source: ATL09
flag_meanings: no_folding goes5_indicates profile_indicates both_indicate
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: cloud_fold_flag
fullnamepath: /gt1l/land_segments/cloud_fold_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_n_seg_ph: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: number of photons
description: Number of photons within each land segment.
source: Derived
origname: n_seg_ph
fullnamepath: /gt1l/land_segments/n_seg_ph
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_terrain_flg: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 2147483647
units: 1
long_name: terrain flag
description: Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
source: Land ATBD section 2.4.8
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: terrain_flg
fullnamepath: /gt1l/land_segments/terrain_flg
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_urban_flag: Array of 32 bit Integers [gt1l_land_segments_delta_time = 0..133]
_FillValue: 2147483647
units: 1
long_name: segment urban flag
description: The urban flag indicates that a segment is likely located over an urban area.
source: Land ATBD section 2.4.17
flag_meanings: not_urban urban
flag_values: 0, 1
origname: urban_flag
fullnamepath: /gt1l/land_segments/urban_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_dem_removal_flag: Array of 16 bit Integers [gt1l_land_segments_delta_time = 0..133]
units: 1
long_name: dem removal flag
description: Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
source: ATBD section 2.4.11
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: dem_removal_flag
fullnamepath: /gt1l/land_segments/dem_removal_flag
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
gt1l_land_segments_h_dif_ref: Array of 32 bit Reals [gt1l_land_segments_delta_time = 0..133]
_FillValue: 3.402823466e+38
units: meters
long_name: h dif from reference
description: Difference between h_te_median and ref_DEM
source: Land ATBD section 2.4
origname: h_dif_ref
fullnamepath: /gt1l/land_segments/h_dif_ref
coordinates: gt1l_land_segments_delta_time gt1l_land_segments_latitude gt1l_land_segments_longitude
quality_assessment_qa_granule_fail_reason: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: qualityInformation
long_name: Granule Failure Reason
description: Flag indicating granule failure reason. 0=no failure; 1=processing error; 2=Insufficient output data was generated; 3=TBD Failure; 4=TBD_Failure; 5=other failure.
source: Operations
flag_meanings: no_failure PROCESS_ERROR INSUFFICIENT_OUTPUT failure_3 failure_4 OTHER_FAILURE
flag_values: 0, 1, 2, 3, 4, 5
valid_min: 0
valid_max: 5
origname: qa_granule_fail_reason
fullnamepath: /quality_assessment/qa_granule_fail_reason
quality_assessment_qa_granule_pass_fail: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: qualityInformation
long_name: Granule Pass Flag
description: Flag indicating granule quality. 0=granule passes automatic QA. 1=granule fails automatic QA.
source: Operations
flag_meanings: PASS FAIL
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: qa_granule_pass_fail
fullnamepath: /quality_assessment/qa_granule_pass_fail
gt3l_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt3l_signal_photons_delta_time = 0..1861]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt3l/signal_photons/classed_pc_flag
coordinates: gt3l_signal_photons_delta_time
gt3l_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt3l_signal_photons_delta_time = 0..1861]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt3l/signal_photons/classed_pc_indx
coordinates: gt3l_signal_photons_delta_time
gt3l_signal_photons_d_flag: Array of 16 bit Integers [gt3l_signal_photons_delta_time = 0..1861]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt3l/signal_photons/d_flag
coordinates: gt3l_signal_photons_delta_time
gt3l_signal_photons_ph_segment_id: Array of 32 bit Integers [gt3l_signal_photons_delta_time = 0..1861]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt3l/signal_photons/ph_segment_id
coordinates: gt3l_signal_photons_delta_time
gt2l_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt2l_signal_photons_delta_time = 0..2874]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt2l/signal_photons/classed_pc_flag
coordinates: gt2l_signal_photons_delta_time
gt2l_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt2l_signal_photons_delta_time = 0..2874]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt2l/signal_photons/classed_pc_indx
coordinates: gt2l_signal_photons_delta_time
gt2l_signal_photons_d_flag: Array of 16 bit Integers [gt2l_signal_photons_delta_time = 0..2874]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt2l/signal_photons/d_flag
coordinates: gt2l_signal_photons_delta_time
gt2l_signal_photons_ph_segment_id: Array of 32 bit Integers [gt2l_signal_photons_delta_time = 0..2874]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt2l/signal_photons/ph_segment_id
coordinates: gt2l_signal_photons_delta_time
ancillary_data_release: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Release Number
description: Release number of the granule. The release number is incremented when the software or ancillary data used to create the granule has been changed.
source: Operations
origname: release
fullnamepath: /ancillary_data/release
ancillary_data_end_geoseg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Ending Geolocation Segment
description: The ending geolocation segment number associated with the data contained within this granule. ICESat granule geographic regions are further refined by geolocation segments. During the geolocation process, a geolocation segment is created approximately every 20m from the start of the orbit to the end. The geolocation segments help align the ATLAS strong a weak beams and provide a common segment length for the L2 and higher products. The geolocation segment indices differ slightly from orbit-to-orbit because of the irregular shape of the Earth. The geolocation segment indices on ATL01 and ATL02 are only approximate because beams have not been aligned at the time of their creation.
source: Derived
origname: end_geoseg
fullnamepath: /ancillary_data/end_geoseg
ancillary_data_version: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Version
description: Version number of this granule within the release. It is a sequential number corresponding to the number of times the granule has been reprocessed for the current release.
source: Operations
origname: version
fullnamepath: /ancillary_data/version
ancillary_data_end_region: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Ending Region
description: The ending product-specific region number associated with the data contained within this granule. ICESat-2 data products are separated by geographic regions. The data contained within a specific region are the same for ATL01 and ATL02. ATL03 regions differ slightly because of different geolocation segment locations caused by the irregular shape of the Earth. The region indices for other products are completely independent.
source: Derived
origname: end_region
fullnamepath: /ancillary_data/end_region
ancillary_data_atlas_sdp_gps_epoch: Array of 64 bit Reals [FakeDim0 = 0..0]
units: seconds since 1980-01-06T00:00:00.000000Z
contentType: auxiliaryInformation
long_name: ATLAS Epoch Offset
description: Number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS Standard Data Product (SDP) epoch (2018-01-01:T00.00.00.000000 UTC). Add this value to delta time parameters to compute full gps_seconds (relative to the GPS epoch) for each data point.
source: Operations
origname: atlas_sdp_gps_epoch
fullnamepath: /ancillary_data/atlas_sdp_gps_epoch
ancillary_data_end_rgt: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Ending Reference Groundtrack
description: The ending reference groundtrack (RGT) number associated with the data contained within this granule. There are 1387 reference groundtrack in the ICESat-2 repeat orbit. The reference groundtrack increments each time the spacecraft completes a full orbit of the Earth and resets to 1 each time the spacecraft completes a full cycle.
source: Derived
valid_min: 1
valid_max: 1387
origname: end_rgt
fullnamepath: /ancillary_data/end_rgt
ancillary_data_end_delta_time: Array of 64 bit Reals [FakeDim0 = 0..0]
units: seconds since 2018-01-01
contentType: auxiliaryInformation
long_name: ATLAS End Time (Actual)
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch at the last data point in the file. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived
origname: end_delta_time
fullnamepath: /ancillary_data/end_delta_time
ancillary_data_end_orbit: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Ending Orbit Number
description: The ending orbit number associated with the data contained within this granule. The orbit number increments each time the spacecraft completes a full orbit of the Earth.
source: Derived
origname: end_orbit
fullnamepath: /ancillary_data/end_orbit
ancillary_data_start_cycle: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Starting Cycle
description: The starting cycle number associated with the data contained within this granule. The cycle number is the counter of the number of 91-day repeat cycles completed by the mission.
source: Derived
valid_min: 0
valid_max: 99
origname: start_cycle
fullnamepath: /ancillary_data/start_cycle
ancillary_data_data_end_utc: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: End UTC Time of Granule (CCSDS-A, Actual)
description: UTC (in CCSDS-A format) of the last data point within the granule.
source: Derived
origname: data_end_utc
fullnamepath: /ancillary_data/data_end_utc
ancillary_data_control: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Control File
description: PGE-specific control file used to generate this granule. To re-use, replace breaks (BR) with linefeeds.
source: Operations
origname: control
fullnamepath: /ancillary_data/control
ancillary_data_start_gpssow: Array of 64 bit Reals [FakeDim0 = 0..0]
units: seconds
contentType: auxiliaryInformation
long_name: Start GPS SOW of Granule (Actual)
description: GPS seconds-of-week of the first data point in the granule.
source: Derived
origname: start_gpssow
fullnamepath: /ancillary_data/start_gpssow
ancillary_data_granule_end_utc: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: End UTC Time of Granule (CCSDS-A, Requested)
description: Requested end time (in UTC CCSDS-A) of this granule.
source: Derived
origname: granule_end_utc
fullnamepath: /ancillary_data/granule_end_utc
ancillary_data_end_cycle: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Ending Cycle
description: The ending cycle number associated with the data contained within this granule. The cycle number is the counter of the number of 91-day repeat cycles completed by the mission.
source: Derived
valid_min: 0
valid_max: 99
origname: end_cycle
fullnamepath: /ancillary_data/end_cycle
ancillary_data_granule_start_utc: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Start UTC Time of Granule (CCSDS-A, Requested)
description: Requested start time (in UTC CCSDS-A) of this granule.
source: Derived
origname: granule_start_utc
fullnamepath: /ancillary_data/granule_start_utc
ancillary_data_land_ca_class: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
description: Canopy classification flag value. (Default = 2)
source: ATBD section 4.12 step 1
long_name: Canopy class value
origname: ca_class
fullnamepath: /ancillary_data/land/ca_class
ancillary_data_land_canopy_flag_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
description: Controls entrance to the canopy flag subroutine . (Default = 1)
source: ATBD section 4.3
long_name: canopy_flag switch
origname: canopy_flag_switch
fullnamepath: /ancillary_data/land/canopy_flag_switch
ancillary_data_land_up_toc_bnd: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Upper bound restricting the search of a top of canopy surface.
description: Upper bound restricting the search of a top of canopy surface. (Default=1.0)
source: ATBD section 4.7 step 3 entered from section 4.8
origname: up_toc_bnd
fullnamepath: /ancillary_data/land/up_toc_bnd
ancillary_data_land_fnlgnd_filter_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: finalground filter switch
description: Controls filtering based on FINALGROUND. (Default = 1)
source: ATBD section 4.13 step 2
origname: fnlgnd_filter_switch
fullnamepath: /ancillary_data/land/fnlgnd_filter_switch
ancillary_data_land_psf: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Point Spread Function
description: Parameter controlling identification of photons around an interpolated surface. (Default = 0.5)
source: ATBD section 4.7 step 12
origname: psf
fullnamepath: /ancillary_data/land/psf
ancillary_data_land_dem_removal_percent_limit: Array of 32 bit Reals [FakeDim0 = 0..0]
units: percent
contentType: auxiliaryInformation
long_name: dem_removal_flag set threshold
description: Percent of photons in land segment failing DEM test to set dem_removal_flag. (default = 20.0)
source: ATBD section 2.4.11
origname: dem_removal_percent_limit
fullnamepath: /ancillary_data/land/dem_removal_percent_limit
ancillary_data_land_atl08_region: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: modelResult
long_name: atl08 region
standard_name: atl08_region
description: ATL08 region(s) encompassed by ATL03 granule being processed
source: Land ATBD 29March2019, Table 2.4
origname: atl08_region
fullnamepath: /ancillary_data/land/atl08_region
ancillary_data_land_can_noise_thresh: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold for reclassification of canopy as noise
description: Threshold, as a number of canopy photons in the CAN_FILT_SEG, used for the reclassification of canopy signal photons. (Default = 75)
source: ATBD section 4.11 step 6
origname: can_noise_thresh
fullnamepath: /ancillary_data/land/can_noise_thresh
ancillary_data_land_relief_hbot: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: lower relief percentile
description: The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.05)
source: ATBD (section 4.5 step 6)
origname: relief_hbot
fullnamepath: /ancillary_data/land/relief_hbot
ancillary_data_land_dem_filter_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: dem_filter switch
description: Controls filtering based on DEM. (Default = 1)
source: ATBD section 4.5 step 5
origname: dem_filter_switch
fullnamepath: /ancillary_data/land/dem_filter_switch
ancillary_data_land_relief_htop: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Upper relief percentile
description: The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.95)
source: ATBD (section 4.5 step 6)
origname: relief_htop
fullnamepath: /ancillary_data/land/relief_htop
ancillary_data_land_dseg_buf: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: DRAGANN segment buffer size
description: DRAGANN segment buffer length in 20m geolocated segments along ground track. (Default=10)
source: ATBD section 4.2.1 step 1
origname: dseg_buf
fullnamepath: /ancillary_data/land/dseg_buf
ancillary_data_land_night_thresh: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold for night
description: Solar elevation threshold for determining night time conditions. (Default =0.0)
source: ATBD section 2.4.9
origname: night_thresh
fullnamepath: /ancillary_data/land/night_thresh
ancillary_data_land_h_canopy_perc: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: h_canopy percentile
description: Percentile component of h_canopy parameter. (Default =0.95)
source: ATBD section 2.2.3
origname: h_canopy_perc
fullnamepath: /ancillary_data/land/h_canopy_perc
ancillary_data_land_up_filt_bnd: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons.
description: Lower bound of the filter window size function. (Default = 46)
source: ATBD section 4.4 step 2
origname: up_filt_bnd
fullnamepath: /ancillary_data/land/up_filt_bnd
ancillary_data_land_lw_filt_bnd: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons.
description: Lower bound of the filter window size function. (Default = 5)
source: ATBD section 4.4 step 2
origname: lw_filt_bnd
fullnamepath: /ancillary_data/land/lw_filt_bnd
ancillary_data_land_ph_removal_percent_limit: Array of 32 bit Reals [FakeDim0 = 0..0]
units: percent
contentType: auxiliaryInformation
long_name: ph_removal_flag set threshold
description: Percent of photons in land segment removed to set ph_removal_flag. (default = 50.0)
source: ATBD section 4.13 step 4
origname: ph_removal_percent_limit
fullnamepath: /ancillary_data/land/ph_removal_percent_limit
ancillary_data_land_canopy_seg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: segment size in canopy filter
description: Segment in number of signal photons for filtering sparse canopy cover. (Default = 500)
source: ATBD section 4.11 step 6
origname: canopy_seg
fullnamepath: /ancillary_data/land/canopy_seg
ancillary_data_land_max_try: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Maximum try count
description: Maximum number of tries to compute a P value in alternative DRAGANN
source: ATBD section 4.2.1 step 17
origname: max_try
fullnamepath: /ancillary_data/land/max_try
ancillary_data_land_bin_size_n: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: neighbor histogram bin size
description: Size of neighbor histogram bins in number of neighbors in DRAGANN. (Default = 1)
source: ATBD (section 4.2 step 4)
origname: bin_size_n
fullnamepath: /ancillary_data/land/bin_size_n
ancillary_data_land_lw_gnd_bnd: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Lower bound restricting the search of a ground surface in canopy cases.
description: Lower bound restricting the search of a ground surface in canopy cases. (Default = -4.0)
source: ATBD section 4.7 step 3
origname: lw_gnd_bnd
fullnamepath: /ancillary_data/land/lw_gnd_bnd
ancillary_data_land_del_mu: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Step size for optimizing the mean parameter of Gaussian function.
description: Step size for optimizing the mean parameter of Gaussian function. (Default = 0.2)
source: ATBD section 4.2 step 7
origname: del_mu
fullnamepath: /ancillary_data/land/del_mu
ancillary_data_land_lw_toc_cut: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Lower cutoff for top of canopy
description: Lower cutoff for top of canopy surface. (Default = 2.0)
source: ATBD section 4.8 step 10
origname: lw_toc_cut
fullnamepath: /ancillary_data/land/lw_toc_cut
ancillary_data_land_class_thresh: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold flag value for classification of photons as signal via input from ATL03
description: Threshold flag value for classification of photons as signal via input from ATL03. (Default =3)
source: ATBD section 4.2 step 17
origname: class_thresh
fullnamepath: /ancillary_data/land/class_thresh
ancillary_data_land_lseg_buf: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Long segment buffer size
description: Overlapping long segment buffer size in 20m geosegments along ground track. (Default=10)
source: ATBD section 4.1 step 2
origname: lseg_buf
fullnamepath: /ancillary_data/land/lseg_buf
ancillary_data_land_lw_toc_bnd: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Lower bound restricting the search of a top of canopy surface.
description: Lower bound restricting the search of a top of canopy surface. (Default = -4.0)
source: section 4.7 step 3 entered from section 4.8
origname: lw_toc_bnd
fullnamepath: /ancillary_data/land/lw_toc_bnd
ancillary_data_land_up_toc_cut: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: upper cutoff of top of canopy surface.
description: Upper cutoff for top of canopy surface. (Default = 150.0)
source: ATBD section 4.8 step 10
origname: up_toc_cut
fullnamepath: /ancillary_data/land/up_toc_cut
ancillary_data_land_gnd_stat_thresh: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold for terrain statistics
description: Minimum percentage of terrain photons to compute statistics upon. (Default =0.05)
source: ATBD section 4.13 step 2
origname: gnd_stat_thresh
fullnamepath: /ancillary_data/land/gnd_stat_thresh
ancillary_data_land_iter_max: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram.
description: Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram. (Default = 10)
source: ATBD section 4.2 step 7
origname: iter_max
fullnamepath: /ancillary_data/land/iter_max
ancillary_data_land_gthresh_factor: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: threshold for Gaussian Elimination
description: Controls threshold for Gaussian Elimination. (Default = 0.1)
source: ATBD sGaussian Rejection section of Appendix A
origname: gthresh_factor
fullnamepath: /ancillary_data/land/gthresh_factor
ancillary_data_land_bright_thresh: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: brightness flag average ph per shot
description: Threshold to set brightness_flag, average ground photons per shot. (Default = 3.0)
source: ATBD section 2.4.21
origname: bright_thresh
fullnamepath: /ancillary_data/land/bright_thresh
ancillary_data_land_dseg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: DRAGANN segment size
description: DRAGANN segment length in 20m geolocated segments along ground track. (Default=170)
source: ATBD section 4.2.1 step 1
origname: dseg
fullnamepath: /ancillary_data/land/dseg
ancillary_data_land_bin_size_h: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: neighbor histogram bin size
description: Histogram bin size for the alternative DRAGANN algorithm. (Default = 1.0)
source: ATBD (section 4.2.1 step 3)
origname: bin_size_h
fullnamepath: /ancillary_data/land/bin_size_h
ancillary_data_land_up_gnd_bnd: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Upper bound restricting the search of a ground surface in canopy cases.
description: Upper bound restricting the search of a ground surface in canopy cases. (Default = 1.0)
source: ATBD (section 4.7 step 3)
origname: up_gnd_bnd
fullnamepath: /ancillary_data/land/up_gnd_bnd
ancillary_data_land_min_nphs: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Minimum input photons
description: Minimum number of input photons from ATL03 to process. (default=1)
source: Operations
origname: min_nphs
fullnamepath: /ancillary_data/land/min_nphs
ancillary_data_land_tc_thresh: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Canopy Flag threshold
description: Percentage threshold for average L-km segment tree cover to be considered canopy. (Default = 5.0)
source: ATBD section 4.3 steps 6 and 7
origname: tc_thresh
fullnamepath: /ancillary_data/land/tc_thresh
ancillary_data_land_te_class: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Terrain class value
description: Terrain classification flag value. (Default = 1)
source: ATBD section 4.12 step 1
origname: te_class
fullnamepath: /ancillary_data/land/te_class
ancillary_data_land_toc_class: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Top of canopy class value
description: Top of canopy classification flag value. (Default = 3)
source: ATBD section 4.12 step 1
origname: toc_class
fullnamepath: /ancillary_data/land/toc_class
ancillary_data_land_iter_gnd: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Iterations of smoothing of interpolated ground surface for ground estimate.
description: Iterations of smoothing of interpolated ground surface for refinement. (Default = 10)
source: ATBD section 4.10 step 1
origname: iter_gnd
fullnamepath: /ancillary_data/land/iter_gnd
ancillary_data_land_max_atl03files: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Maximum number of input ATL03s
description: Maximum number of input ATL03 files. (Default = 200)
source: Operations
origname: max_atl03files
fullnamepath: /ancillary_data/land/max_atl03files
ancillary_data_land_noise_class: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Noise class value
description: Noise classification flag value. (Default = 0)
source: ATBD section 4.12 step 1
origname: noise_class
fullnamepath: /ancillary_data/land/noise_class
ancillary_data_land_outlier_filter_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: outlier_filter switch
description: Controls entrance to the outlier filter subroutine. (Default = 1)
source: ATBD section 4.6
origname: outlier_filter_switch
fullnamepath: /ancillary_data/land/outlier_filter_switch
ancillary_data_land_dragann_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: DRAGANN switch
description: Controls entrance to the DRAGANN subroutine. (Default =1)
source: ATBD section 4.2
origname: dragann_switch
fullnamepath: /ancillary_data/land/dragann_switch
ancillary_data_land_proc_geoseg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Geosegment process interval length
description: Geosegment process interval length. This controls the amount read from ATL03 and ATL09 at a time. (Default = 500000).
source: Operations
origname: proc_geoseg
fullnamepath: /ancillary_data/land/proc_geoseg
ancillary_data_land_can_stat_thresh: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold for canopy statistics
description: Minimum percentage of canopy photons to compute statistics upon. (Default =0.05)
source: ATBD section 4.14.1 step 1
origname: can_stat_thresh
fullnamepath: /ancillary_data/land/can_stat_thresh
ancillary_data_land_lseg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Long segment size
description: Long segment size in number of 20 meter segments along ground track. (Default=500)
source: ATBD section 4.1 step 1
origname: lseg
fullnamepath: /ancillary_data/land/lseg
ancillary_data_land_max_atl09files: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Maximum number of input ATL09s
description: Maximum number of input ATL09 files. (Default = 200)
source: Operations
origname: max_atl09files
fullnamepath: /ancillary_data/land/max_atl09files
ancillary_data_land_ref_dem_limit: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: DEM threshold
description: Reference DEM limit used to reclassify signal as noise. (default = 120.0)
source: ATBD section 4.5 step 4
origname: ref_dem_limit
fullnamepath: /ancillary_data/land/ref_dem_limit
ancillary_data_land_max_peaks: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Maximum number of Gaussian peaks to fit in the data set
description: Maximum number of Gaussian peaks to fit in the data set in DRAGANN. (Default =10)
source: ATBD section 4.2 step 9
origname: max_peaks
fullnamepath: /ancillary_data/land/max_peaks
ancillary_data_land_stat_thresh: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Threshold for land statistics
description: Minimum number of photons to compute statistics upon. (Default =50)
source: ATBD section 2 intro paragraph
origname: stat_thresh
fullnamepath: /ancillary_data/land/stat_thresh
ancillary_data_land_sig_rsq_search: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters^2
contentType: auxiliaryInformation
long_name: Square Radius of filter for canopy
description: Top of canopy refinement square search radius. (Default = 225.0)
source: ATBD section 4.8 step 6
origname: sig_rsq_search
fullnamepath: /ancillary_data/land/sig_rsq_search
ancillary_data_land_del_amp: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Step Gaussian Amplitude optimization
description: Step size for optimizing the amplitude variable of Gaussian function. (Default = 1.0)
source: ATBD section 4.2 step 7
origname: del_amp
fullnamepath: /ancillary_data/land/del_amp
ancillary_data_land_sseg: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
long_name: Short Segment Length
description: Short segment length in meters. (Default = 100.0)
source: ATBD section 4.13 step 1
origname: sseg
fullnamepath: /ancillary_data/land/sseg
ancillary_data_land_shp_param: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Exponential coefficient for controlling the exponential decay of the filter window size as a function of number of signal photons.
description: Exponential coefficient of the filter window size as a function. (Default = 21.0E-06)
source: ATBD section 4.4 step 2
origname: shp_param
fullnamepath: /ancillary_data/land/shp_param
ancillary_data_land_del_sigma: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Step size for optimizing the standard deviation parameter of Gaussian function.
description: Step size for optimizing the standard deviation parameter of Gaussian function. (Default = 0.5)
source: ATBD section 4.2 step 7
origname: del_sigma
fullnamepath: /ancillary_data/land/del_sigma
ancillary_data_land_cloud_filter_switch: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: cloud_filter switch
description: Controls entrance to the cloud_filter subroutine. (Default = 0)
source: ATBD section 4.1.1
origname: cloud_filter_switch
fullnamepath: /ancillary_data/land/cloud_filter_switch
ancillary_data_land_n_dec_mode: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Mode decimal parameter
description: Number of decimal places to consider in mode computation. (Default =1)
source: ATBD needed for section 4.13 step 3(h_te_mode)
origname: n_dec_mode
fullnamepath: /ancillary_data/land/n_dec_mode
ancillary_data_land_ref_finalground_limit: Array of 32 bit Reals [FakeDim0 = 0..0]
units: meters
contentType: auxiliaryInformation
description: Reference finalground limit used to reclassify signal as noise. (default = 150.0)
source: ATBD section 4.13 step 2
long_name: finalground threshold
origname: ref_finalground_limit
fullnamepath: /ancillary_data/land/ref_finalground_limit
ancillary_data_land_p_static: Array of 32 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Dragann Parameter
description: Parameter for controlling the search radius in nearest neighbor search in DRAGANN. (Default = 20)
source: ATBD section 4.2 step 1
origname: p_static
fullnamepath: /ancillary_data/land/p_static
ancillary_data_start_delta_time: Array of 64 bit Reals [FakeDim0 = 0..0]
units: seconds since 2018-01-01
contentType: auxiliaryInformation
long_name: ATLAS Start Time (Actual)
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch at the first data point in the file. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived
origname: start_delta_time
fullnamepath: /ancillary_data/start_delta_time
ancillary_data_start_geoseg: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Starting Geolocation Segment
description: The starting geolocation segment number associated with the data contained within this granule. ICESat granule geographic regions are further refined by geolocation segments. During the geolocation process, a geolocation segment is created approximately every 20m from the start of the orbit to the end. The geolocation segments help align the ATLAS strong a weak beams and provide a common segment length for the L2 and higher products. The geolocation segment indices differ slightly from orbit-to-orbit because of the irregular shape of the Earth. The geolocation segment indices on ATL01 and ATL02 are only approximate because beams have not been aligned at the time of their creation.
source: Derived
origname: start_geoseg
fullnamepath: /ancillary_data/start_geoseg
ancillary_data_start_orbit: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Starting Orbit Number
description: The starting orbit number associated with the data contained within this granule. The orbit number increments each time the spacecraft completes a full orbit of the Earth.
source: Derived
origname: start_orbit
fullnamepath: /ancillary_data/start_orbit
ancillary_data_data_start_utc: Array of Strings [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Start UTC Time of Granule (CCSDS-A, Actual)
description: UTC (in CCSDS-A format) of the first data point within the granule.
source: Derived
origname: data_start_utc
fullnamepath: /ancillary_data/data_start_utc
ancillary_data_end_gpsweek: Array of 32 bit Integers [FakeDim0 = 0..0]
units: weeks from 1980-01-06
contentType: auxiliaryInformation
long_name: Ending GPSWeek of Granule (Actual)
description: GPS week number of the last data point in the granule.
source: Derived
origname: end_gpsweek
fullnamepath: /ancillary_data/end_gpsweek
ancillary_data_start_rgt: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Starting Reference Groundtrack
description: The starting reference groundtrack (RGT) number associated with the data contained within this granule. There are 1387 reference groundtrack in the ICESat-2 repeat orbit. The reference groundtrack increments each time the spacecraft completes a full orbit of the Earth and resets to 1 each time the spacecraft completes a full cycle.
source: Derived
valid_min: 1
valid_max: 1387
origname: start_rgt
fullnamepath: /ancillary_data/start_rgt
ancillary_data_end_gpssow: Array of 64 bit Reals [FakeDim0 = 0..0]
units: seconds
contentType: auxiliaryInformation
long_name: Ending GPS SOW of Granule (Actual)
description: GPS seconds-of-week of the last data point in the granule.
source: Derived
origname: end_gpssow
fullnamepath: /ancillary_data/end_gpssow
ancillary_data_qa_at_interval: Array of 64 bit Reals [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: QA Along-Track Interval
description: Statistics time interval for along-track QA data.
source: control
origname: qa_at_interval
fullnamepath: /ancillary_data/qa_at_interval
ancillary_data_start_region: Array of 32 bit Integers [FakeDim0 = 0..0]
units: 1
contentType: auxiliaryInformation
long_name: Starting Region
description: The starting product-specific region number associated with the data contained within this granule. ICESat-2 data products are separated by geographic regions. The data contained within a specific region are the same for ATL01 and ATL02. ATL03 regions differ slightly because of different geolocation segment locations caused by the irregular shape of the Earth. The region indices for other products are completely independent.
source: Derived
origname: start_region
fullnamepath: /ancillary_data/start_region
ancillary_data_start_gpsweek: Array of 32 bit Integers [FakeDim0 = 0..0]
units: weeks from 1980-01-06
contentType: auxiliaryInformation
long_name: Start GPSWeek of Granule (Actual)
description: GPS week number of the first data point in the granule.
source: Derived
origname: start_gpsweek
fullnamepath: /ancillary_data/start_gpsweek
gt3r_signal_photons_classed_pc_flag: Array of 16 bit Integers [gt3r_signal_photons_delta_time = 0..5879]
units: 1
long_name: photon land atbd classification
description: Land Vegetation ATBD classification flag for each photon as either noise, ground, canopy, and top of canopy. 0 = noise, 1 = ground, 2 = canopy, or 3 = top of canopy.
source: Land ATBD section 4.10
flag_meanings: noise ground canopy top_of_canopy
flag_values: 0, 1, 2, 3
origname: classed_pc_flag
fullnamepath: /gt3r/signal_photons/classed_pc_flag
coordinates: gt3r_signal_photons_delta_time
gt3r_signal_photons_classed_pc_indx: Array of 32 bit Integers [gt3r_signal_photons_delta_time = 0..5879]
units: 1
contentType: referenceInformation
long_name: indicies of classed photons
description: Index (1-based) of the ATL08 classified signal photon from the start of the ATL03 geolocation segment specified on the ATL08 product at the photon rate in the corresponding parameter, ph_segment_id. This index traces back to specific photon within a 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: classed_pc_indx
fullnamepath: /gt3r/signal_photons/classed_pc_indx
coordinates: gt3r_signal_photons_delta_time
gt3r_signal_photons_d_flag: Array of 16 bit Integers [gt3r_signal_photons_delta_time = 0..5879]
units: 1
long_name: dragann flag
description: Flag indicating the labeling of DRAGANN noise filtering for a given photon.
source: Land ATBD section 2.3.5
flag_meanings: noise signal
flag_values: 0, 1
origname: d_flag
fullnamepath: /gt3r/signal_photons/d_flag
coordinates: gt3r_signal_photons_delta_time
gt3r_signal_photons_ph_segment_id: Array of 32 bit Integers [gt3r_signal_photons_delta_time = 0..5879]
units: 1
contentType: referenceInformation
long_name: segment id of photon
description: Segment ID of photons tracing back to specific 20m segment_id on ATL03. The unique identifier for tracing each ATL08 signal photon to the photon on ATL03 is the segment_id, orbit, and classed_pc_indx. The unique identifier for tracing each ATL08 signal photon to the corresponding photon record on ATL03 is the segment_id, orbit, cycle, and classed_pc_indx. Orbit and cycle intervals for the granule are found in the /ancillary_data. The timestamp of each orbit transition is found in the /orbit_info group.
source: Retained from prior a_alt_science_ph packet
origname: ph_segment_id
fullnamepath: /gt3r/signal_photons/ph_segment_id
coordinates: gt3r_signal_photons_delta_time
gt3r_land_segments_segment_watermask: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 255
units: 1
long_name: segment watermask
description: Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
source: ATBD section 2.4.15
flag_meanings: no_water water
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: segment_watermask
fullnamepath: /gt3r/land_segments/segment_watermask
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_delta_time_end: Array of 64 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time end
description: Time of the last photon contained within the data segment, in seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_end
fullnamepath: /gt3r/land_segments/delta_time_end
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_rgt: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
contentType: referenceInformation
long_name: reference ground track
description: The reference ground track (RGT) is the track on the earth at which a specified unit vector within the observatory is pointed. Under nominal operating conditions, there will be no data collected along the RGT, as the RGT is spanned by GT3 and GT4. During slews or off-pointing, it is possible that ground tracks may intersect the RGT. The ICESat-2 mission has 1387 RGTs.
source: Operations
valid_min: 1
valid_max: 1387
origname: rgt
fullnamepath: /gt3r/land_segments/rgt
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_dem_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
units: 1
contentType: referenceInformation
long_name: dem source flag
description: Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
source: Atmosphere ATBD
flag_meanings: none arctic gmted mss antarctic
flag_values: 0, 1, 2, 3, 4
valid_min: 0
valid_max: 4
origname: dem_flag
fullnamepath: /gt3r/land_segments/dem_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_msw_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
units: 1
long_name: multiple scattering warning flag
description: Multiple Scattering warning flag. The multiple scattering warning flag (ATL09 parameter msw_flag) has values from -1 to 5 where zero means no multiple scattering and 5 the greatest. If no layers were detected, then msw_flag = 0. If blowing snow is detected and its estimated optical depth is greater than or equal to 0.5, then msw_flag = 5. If the blowing snow optical depth is less than 0.5, then msw_flag = 4. If no blowing snow is detected but there are cloud or aerosol layers detected, the msw_flag assumes values of 1 to 3 based on the height of the bottom of the lowest layer: < 1 km, msw_flag = 3; 1-3 km, msw_flag = 2; > 3km, msw_flag = 1. A value of -1 indicates that the signal to noise of the data was too low to reliably ascertain the presence of cloud or blowing snow. We expect values of -1 to occur only during daylight.
source: ATL09
flag_meanings: cannot_determine no_layers layer_gt_3km layer_between_1_and_3_km layer_lt_1km blow_snow_od_lt_0.5 blow_snow_od_gt_0.5
flag_values: -1, 0, 1, 2, 3, 4, 5
origname: msw_flag
fullnamepath: /gt3r/land_segments/msw_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_cloud_flag_atm: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
units: 1
long_name: cloud flag atm
description: Cloud confidence flag from ATL09 that indicates the number of cloud or aerosol layers identified in each 25Hz atmospheric profile. If the flag is greater than 0, aerosols or clouds could be present. Valid range is 0 - 10.
source: ATL09
valid_min: 0
valid_max: 10
origname: cloud_flag_atm
fullnamepath: /gt3r/land_segments/cloud_flag_atm
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_snr: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
long_name: signal to noise ratio
description: The signal to noise ratio of geolocated photons as determined by the ratio of the superset of ATL03 signal and DRAGANN found signal photons used for processing the ATL08 segments to the background photons (i.e. noise) within the same ATL08 segments.
source: ATBD section 2.5.14
origname: snr
fullnamepath: /gt3r/land_segments/snr
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: height canopy
description: 98% height of all the individual canopy relative heights for the segment above the estimated terrain surface. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_canopy
fullnamepath: /gt3r/land_segments/canopy/h_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_canopy_rh_conf: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
contentType: modelResult
long_name: canopy relative height confidence
description: Canopy relative height confidence flag based on percentage of ground and canopy photons within a segment: 0 (<5% canopy), 1 (>5% canopy, <5% ground), 2 (>5% canopy, >5% ground).
source: Land/Veg ATBD 13March2019, Section 2.2.21
flag_meanings: <5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
flag_values: 0, 1, 2
valid_min: 0
valid_max: 2
origname: canopy_rh_conf
fullnamepath: /gt3r/land_segments/canopy/canopy_rh_conf
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_median_canopy_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment median canopy height
description: The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.6
origname: h_median_canopy_abs
fullnamepath: /gt3r/land_segments/canopy/h_median_canopy_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_min_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum canopy height
description: The minimum of relative individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 2.2.10
origname: h_min_canopy
fullnamepath: /gt3r/land_segments/canopy/h_min_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_mean_canopy_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute mean canopy height
description: Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.4
origname: h_mean_canopy_abs
fullnamepath: /gt3r/land_segments/canopy/h_mean_canopy_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_median_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: median canopy height
description: The median of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. This parameter should be equivalent to RH50 reported in the literature.
source: Land ATBD section 2.2.8
origname: h_median_canopy
fullnamepath: /gt3r/land_segments/canopy/h_median_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_canopy_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute segment canopy height
description: The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.2
origname: h_canopy_abs
fullnamepath: /gt3r/land_segments/canopy/h_canopy_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_toc_roughness: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: top of canopy roughness
description: Standard deviation of the relative heights of all photons classified as top of canopy within the segment
source: Land ATBD section 4.12
origname: toc_roughness
fullnamepath: /gt3r/land_segments/canopy/toc_roughness
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_min_canopy_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute minimum canopy height
description: The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
source: Land ATBD section 2.2.9
origname: h_min_canopy_abs
fullnamepath: /gt3r/land_segments/canopy/h_min_canopy_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_dif_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy diff to median height
description: Difference between h_canopy and h_median_canopy
source: Land ATBD section 4.12
origname: h_dif_canopy
fullnamepath: /gt3r/land_segments/canopy/h_dif_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_canopy_quad: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
long_name: canopy quadratic mean
description: The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
source: Land ATBD section 4.12
_FillValue: 3.402823466e+38
units: meters
origname: h_canopy_quad
fullnamepath: /gt3r/land_segments/canopy/h_canopy_quad
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_n_ca_photons: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: number canopy photons
description: The number of photons classified as canopy within the segment.
source: Land ATBD section 4.12
origname: n_ca_photons
fullnamepath: /gt3r/land_segments/canopy/n_ca_photons
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_centroid_height: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: centroid height
description: Optical centroid of all photons classified as either canopy or ground points within the segment. The heights used in this calculation are absolute heights above the reference ellipsoid. This parameter is equivalent to the centroid height produced ICESat GLA14.
source: Land ATBD section 2.2.22
origname: centroid_height
fullnamepath: /gt3r/land_segments/canopy/centroid_height
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_canopy_h_metrics_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24][ds_metrics = 0..8]
long_name: canopy absolute height metrics
description: Height metrics based on the cumulative distribution of absolute canopy heights above the WGS84 Ellipsoid. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
_FillValue: 3.402823466e+38
units: meters
origname: canopy_h_metrics_abs
fullnamepath: /gt3r/land_segments/canopy/canopy_h_metrics_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_landsat_perc: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
long_name: landsat percentage canopy
description: Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
source: Land ATBD section 2.2.24
origname: landsat_perc
fullnamepath: /gt3r/land_segments/canopy/landsat_perc
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_mean_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: mean canopy height
description: Mean of individual relative canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface.
source: Land ATBD section 4.12
origname: h_mean_canopy
fullnamepath: /gt3r/land_segments/canopy/h_mean_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_canopy_h_metrics: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24][ds_metrics = 0..8]
_FillValue: 3.402823466e+38
units: meters
long_name: canopy height metrics
description: Height metrics based on the cumulative distribution of relative canopy heights above the interpolated ground surface. The height metrics are calculated at the following percentiles: 25,50,60,70,75,80,85,90,95%.
source: Land ATBD section 2.2.3
origname: canopy_h_metrics
fullnamepath: /gt3r/land_segments/canopy/canopy_h_metrics
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_n_toc_photons: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: number top of canopy photons
description: The number of photons classified as top of canopy within the segment.
source: Land ATBD section 4.12
origname: n_toc_photons
fullnamepath: /gt3r/land_segments/canopy/n_toc_photons
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_canopy_flag: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 2147483647
units: 1
long_name: canopy flag
description: Flag indicating that canopy was detected using the Landsat Tree Cover Continuous Fields data product. If percent of canopy cover along the L-km segment is greater than 5%, then canopy is assumed to be present; else, no canopy is assumed present.
source: Land ATBD section 2.2.22
flag_meanings: no_canopy_present canopy_present
flag_values: 0, 1
origname: canopy_flag
fullnamepath: /gt3r/land_segments/canopy/canopy_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_landsat_flag: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 2147483647
units: 1
long_name: landsat flag
description: Flag indicating that more than 50% of the Landsat Continuous Cover product have values > 100 for the L-Km segment. Canopy is assumed present along the L-km segment if landsat_flag is 1.
source: Land ATBD section 2.2.25
flag_meanings: canopy_not_assumed_present canopy_assumed_present
flag_values: 0, 1
origname: landsat_flag
fullnamepath: /gt3r/land_segments/canopy/landsat_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_max_canopy_abs: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: absolute maximum canopy height
description: Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
source: Land ATBD section 2.2.11
origname: h_max_canopy_abs
fullnamepath: /gt3r/land_segments/canopy/h_max_canopy_abs
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_canopy_uncertainty: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: segment canopy height uncertainty
description: Uncertainty of the relative canopy heights for the segment. Incorporates all systematic uncertainties as well as uncertainty from errors of identified photons. See section 1 and equations 1.4 and 1.5 in the Land ATBD
source: Land ATBD section 1.5
origname: h_canopy_uncertainty
fullnamepath: /gt3r/land_segments/canopy/h_canopy_uncertainty
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_canopy_openness: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
long_name: canopy openness
description: Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
source: Land ATBD section 4.12
origname: canopy_openness
fullnamepath: /gt3r/land_segments/canopy/canopy_openness
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_canopy_h_max_canopy: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum canopy height
description: Relative maximum of individual canopy heights within segment. Relative canopy heights have been computed by differencing the canopy photon height from the estimated terrain surface. Should be equivalent to RH100 metric reported in the literature.
source: Land ATBD section 2.2.12
origname: h_max_canopy
fullnamepath: /gt3r/land_segments/canopy/h_max_canopy
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_sigma_across: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas y
description: Total cross-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_across. Sigma_atlas_y is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_across
fullnamepath: /gt3r/land_segments/sigma_across
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_uncertainty: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: uncertainty of h_te_mean
description: Uncertainty of the mean terrain height for the segment. This uncertainty incorporates all systematic uncertainties(e.g. timing orbits, geolocation,etc.) as well as uncertainty from errors of identified photons. This parameter is described in section 1, equation 1.4
source: Land ATBD section 4.11
origname: h_te_uncertainty
fullnamepath: /gt3r/land_segments/terrain/h_te_uncertainty
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_mean: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: mean terrain height
description: The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mean
fullnamepath: /gt3r/land_segments/terrain/h_te_mean
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_min: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: minimum terrain height
description: The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_min
fullnamepath: /gt3r/land_segments/terrain/h_te_min
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_interp: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: interpolated terrain surface height
description: Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
source: Land ATBD section 4.9
origname: h_te_interp
fullnamepath: /gt3r/land_segments/terrain/h_te_interp
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_max: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: maximum terrain height
description: The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_max
fullnamepath: /gt3r/land_segments/terrain/h_te_max
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_skew: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: skew of terrain heights
description: The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_skew
fullnamepath: /gt3r/land_segments/terrain/h_te_skew
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_median: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: median terrain height
description: The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_median
fullnamepath: /gt3r/land_segments/terrain/h_te_median
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_best_fit: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: segment terrain height best fit
description: The best fit terrain elevation at the the mid-point location of each 100m segment. The mid-segment terrain elevation is determined by selecting the best of three fits- linear, 3rd order and 4th order polynomials - to the terrain photons and interpolating the elevation at the mid-point location of the 100 m segment. For the linear fit, a slope correction and weighting is applied to each ground photon based on the distance to the slope height at the center of the segment.
source: Land ATBD section 2.1.15
origname: h_te_best_fit
fullnamepath: /gt3r/land_segments/terrain/h_te_best_fit
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_std: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
long_name: segment terrain roughness
description: The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
_FillValue: 3.402823466e+38
units: meters
origname: h_te_std
fullnamepath: /gt3r/land_segments/terrain/h_te_std
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_terrain_slope: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
long_name: segment terrain slope
description: The along-track slope of terrain, within each segment;computed by a linear fit of terrain classified photons. Slope is in units of delta height over delta along track distance.
source: Land ATBD section 4.11
origname: terrain_slope
fullnamepath: /gt3r/land_segments/terrain/terrain_slope
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_n_te_photons: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: number of ground photons
description: The number of the photons classified as terrain within the segment.
source: Land ATBD section 4.11
origname: n_te_photons
fullnamepath: /gt3r/land_segments/terrain/n_te_photons
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_h_te_mode: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: mode of terrain heights
description: The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
source: Land ATBD section 4.11
origname: h_te_mode
fullnamepath: /gt3r/land_segments/terrain/h_te_mode
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_layer_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
contentType: modelResult
long_name: consolidated cloud flag
description: This flag is a combination of multiple flags (cloud_flag_atm, cloud_flag_asr, and bsnow_con) and takes daytime/nighttime into consideration. A value of 1 means clouds or blowing snow are likely present. A value of 0 indicates the likely absence of clouds or blowing snow.
source: ATL09
flag_meanings: likely_clear likely_cloudy
flag_values: 0, 1
origname: layer_flag
fullnamepath: /gt3r/land_segments/layer_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_segment_snowcover: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
units: 1
long_name: segment snowcover
description: Daily snow/ice cover from ATL09 at the 25 Hz rate(275m) indicating likely presence of snow and ice within each segment. 0=ice free water; 1=snow free land; 2=snow; 3=ice.
source: ATBD section 4.2.16
flag_meanings: ice_free_water snow_free_land snow ice
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: segment_snowcover
fullnamepath: /gt3r/land_segments/segment_snowcover
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_beam_azimuth: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam azimuth
description: Azimuth(in radians) of the unit pointing vector for the reference photon in the local ENU frame in radians. The angle is measured from north and positive towards East.
source: ATL03
origname: beam_azimuth
fullnamepath: /gt3r/land_segments/beam_azimuth
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_solar_azimuth: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: degrees_east
contentType: referenceInformation
long_name: solar azimuth
description: The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
source: ATL03g ATBD
origname: solar_azimuth
fullnamepath: /gt3r/land_segments/solar_azimuth
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_psf_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
contentType: referenceInformation
long_name: point spread function flag
description: Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
source: Land/Veg ATBD
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: psf_flag
fullnamepath: /gt3r/land_segments/psf_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_longitude: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: degrees
long_name: longitude
standard_name: longitude
description: Longitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -180.0000000
valid_max: 180.0000000
origname: longitude
fullnamepath: /gt3r/land_segments/longitude
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude
gt3r_land_segments_latitude: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: degrees
long_name: latitude
standard_name: latitude
description: Latitude of the center-most signal photon within each segment.
source: Land ATBD section 2.4
valid_min: -90.00000000
valid_max: 90.00000000
origname: latitude
fullnamepath: /gt3r/land_segments/latitude
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_longitude
gt3r_land_segments_segment_id_end: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
contentType: referenceInformation
long_name: end geolocation segment bin
description: Geolocation segment number of the last photon in the land segment.
source: ATL03
origname: segment_id_end
fullnamepath: /gt3r/land_segments/segment_id_end
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_surf_type: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24][ds_surf_type = 0..4]
units: 1
contentType: referenceInformation
long_name: surface type
description: Flags describing which surface types this interval is associated with. 0=not type, 1=is type. Order of array is land, ocean, sea ice, land ice, inland water.
source: ATL03 ATBD, Section 4
flag_meanings: not_type is_type
flag_values: 0, 1
valid_min: 0
valid_max: 1
origname: surf_type
fullnamepath: /gt3r/land_segments/surf_type
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_brightness_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
units: 1
long_name: brightness flag
description: Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
source: Land ATBD section 2.4.21
flag_meanings: not_bright_surface bright_surface
flag_values: 0, 1
origname: brightness_flag
fullnamepath: /gt3r/land_segments/brightness_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_segment_landcover: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 255
units: 1
long_name: segment landcover
description: IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
source: ATBD section 2.4.14
flag_meanings: Water Evergreen_Needleleaf_Forest Evergreen_Broadleaf_Forest Deciduous_Needleleaf_Forest Deciduous_Broadleaf_Forest Mixed_Forest Closed_Shrublands Open_Shrubland Woody_Savanna Savanna Grassland Wetland Croplands Urban Crop_Mosaic Permanent_Snow Barren
flag_values: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16
valid_min: 0
valid_max: 16
origname: segment_landcover
fullnamepath: /gt3r/land_segments/segment_landcover
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_ph_removal_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: ph removal flag
description: Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
source: ATBD section 4.13
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: ph_removal_flag
fullnamepath: /gt3r/land_segments/ph_removal_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_asr: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
long_name: apparent surface reflectance
description: Apparent surface reflectance
source: ATL09
origname: asr
fullnamepath: /gt3r/land_segments/asr
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_sigma_atlas_land: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas land
description: Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
source: Land ATBD section 2.5.13
origname: sigma_atlas_land
fullnamepath: /gt3r/land_segments/sigma_atlas_land
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_segment_id_beg: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
contentType: referenceInformation
long_name: begin geolocation segment bin
description: Geolocation segment number of the first photon in the land segment.
source: ATL03
origname: segment_id_beg
fullnamepath: /gt3r/land_segments/segment_id_beg
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_sigma_along: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas x
description: Total along-track uncertainty due to PPD and POD knowledge. Read from ATL03 product gtx/geolocation/sigma_along. Sigma_atlas_x is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
origname: sigma_along
fullnamepath: /gt3r/land_segments/sigma_along
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_dem_h: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
contentType: referenceInformation
long_name: dem height
description: Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
source: GIMP, GMTED,MSS
origname: dem_h
fullnamepath: /gt3r/land_segments/dem_h
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_beam_coelev: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: beam co-elevation
description: Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
source: ATL03
origname: beam_coelev
fullnamepath: /gt3r/land_segments/beam_coelev
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_sigma_topo: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: 1
contentType: referenceInformation
long_name: sigma atlas topo
description: Total uncertainty that include sigma_h plus geolocation uncertainty due to local slope (equation 1.3). The local slope is multiplied by the geolocation uncertainty factor. This will be used to determine the total vertical geolocation error due to ranging and local slope.
source: Land ATBD section 2.5.12
origname: sigma_topo
fullnamepath: /gt3r/land_segments/sigma_topo
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_night_flag: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 2147483647
units: 1
long_name: night flag
description: Flag indicating the data were acquired in night conditions: 0=day, 1=night. Flag is derived from solar elevation at the geolocated segment. IF solar elevation is above threshold it is day, if not then it is night. Threshold is set in atlas_l3a_const_mod.
source: Land ATBD section 2.4.8
flag_meanings: day night
flag_values: 0, 1
origname: night_flag
fullnamepath: /gt3r/land_segments/night_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_delta_time_beg: Array of 64 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: delta time begin
description: Time of the first photon contained within the data segment, in seconds since the ATLAS SDP GPS Epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Derived (gps_seconds-gps_sec_offset)
origname: delta_time_beg
fullnamepath: /gt3r/land_segments/delta_time_beg
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_sigma_h: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
contentType: referenceInformation
long_name: height uncertainty
description: Estimated uncertainty for the reference photon bounce point ellipsoid height: 1- sigma (m) provided at the geolocation segment rate on ATL03. Sigma_h is reported on ATL08 as the uncertainty of the center-most reference photon of the 100m ATL08 segment.
source: ATL03
_FillValue: 3.402823466e+38
units: 1
origname: sigma_h
fullnamepath: /gt3r/land_segments/sigma_h
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_last_seg_extend: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: kilometers
long_name: last segment extended
standard_name: last_seg_extend
description: The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
source: Land ATBD 13March2019, Section 2.4.20
origname: last_seg_extend
fullnamepath: /gt3r/land_segments/last_seg_extend
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_atlas_pa: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: radians
contentType: referenceInformation
long_name: atlas pointing angle
description: Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
source: ATL03
origname: atlas_pa
fullnamepath: /gt3r/land_segments/atlas_pa
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_solar_elevation: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: degrees
contentType: referenceInformation
long_name: solar elevation
description: Solar Angle above or below the plane tangent to the ellipsoid surface at the laser spot. Positive values mean the sun is above the horizon, while negative values mean it is below the horizon. The effect of atmospheric refraction is not included. This is a low precision value, with approximately TBD degree accuracy.
source: ATL03g ATBD
origname: solar_elevation
fullnamepath: /gt3r/land_segments/solar_elevation
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_cloud_fold_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 127
contentType: modelResult
long_name: cloud folding flag
description: Flag that indicates this profile likely contains cloud signal folded down from above 15 km to the last 2-3 km of the profile. See ATL09 ATBD Table 3.9 for detailed flag value meanings.
source: ATL09
flag_meanings: no_folding goes5_indicates profile_indicates both_indicate
flag_values: 0, 1, 2, 3
valid_min: 0
valid_max: 3
origname: cloud_fold_flag
fullnamepath: /gt3r/land_segments/cloud_fold_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_n_seg_ph: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: number of photons
description: Number of photons within each land segment.
source: Derived
origname: n_seg_ph
fullnamepath: /gt3r/land_segments/n_seg_ph
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_terrain_flg: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 2147483647
units: 1
long_name: terrain flag
description: Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
source: Land ATBD section 2.4.8
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: terrain_flg
fullnamepath: /gt3r/land_segments/terrain_flg
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_urban_flag: Array of 32 bit Integers [gt3r_land_segments_delta_time = 0..24]
_FillValue: 2147483647
units: 1
long_name: segment urban flag
description: The urban flag indicates that a segment is likely located over an urban area.
source: Land ATBD section 2.4.17
flag_meanings: not_urban urban
flag_values: 0, 1
origname: urban_flag
fullnamepath: /gt3r/land_segments/urban_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_dem_removal_flag: Array of 16 bit Integers [gt3r_land_segments_delta_time = 0..24]
units: 1
long_name: dem removal flag
description: Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
source: ATBD section 2.4.11
flag_meanings: below_threshold above_threshold
flag_values: 0, 1
origname: dem_removal_flag
fullnamepath: /gt3r/land_segments/dem_removal_flag
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
gt3r_land_segments_h_dif_ref: Array of 32 bit Reals [gt3r_land_segments_delta_time = 0..24]
_FillValue: 3.402823466e+38
units: meters
long_name: h dif from reference
description: Difference between h_te_median and ref_DEM
source: Land ATBD section 2.4
origname: h_dif_ref
fullnamepath: /gt3r/land_segments/h_dif_ref
coordinates: gt3r_land_segments_delta_time gt3r_land_segments_latitude gt3r_land_segments_longitude
ds_metrics: Array of 16 bit Integers [ds_metrics = 0..8]
units: 1
contentType: referenceInformation
long_name: Metrics
description: Dimension scale for metrics.
flag_meanings: metrics1 metrics2 metrics3 metrics4 metrics5 metrics6 metrics7 metrics8 metrics9
flag_values: 1, 2, 3, 4, 5, 6, 7, 8, 9
valid_min: 1
valid_max: 4
origname: ds_metrics
fullnamepath: /ds_metrics
ds_surf_type: Array of 32 bit Integers [ds_surf_type = 0..4]
units: 1
contentType: auxiliaryInformation
long_name: Surface Type Dimension Scale
description: Dimension scale indexing the surface type array. Index=1 corresponds to Land; index = 2 corresponds to Ocean; Index = 3 corresponds to SeaIce; Index=4 corresponds to LandIce; Index=5 corresponds to InlandWater
flag_meanings: land ocean seaice landice inland_water
flag_values: 1, 2, 3, 4, 5
valid_min: 1
valid_max: 5
origname: ds_surf_type
fullnamepath: /ds_surf_type
gt1l_land_segments_delta_time: Array of 64 bit Reals [gt1l_land_segments_delta_time = 0..133]
units: seconds since 2018-01-01
long_name: mean_pass_time
standard_name: time
description: Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Land ATBD section 2.4
coordinates: latitude longitude
origname: delta_time
fullnamepath: /gt1l/land_segments/delta_time
gt1l_signal_photons_delta_time: Array of 64 bit Reals [gt1l_signal_photons_delta_time = 0..17464]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt1l/signal_photons/delta_time
gt1r_land_segments_delta_time: Array of 64 bit Reals [gt1r_land_segments_delta_time = 0..217]
units: seconds since 2018-01-01
long_name: mean_pass_time
standard_name: time
description: Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Land ATBD section 2.4
coordinates: latitude longitude
origname: delta_time
fullnamepath: /gt1r/land_segments/delta_time
gt1r_signal_photons_delta_time: Array of 64 bit Reals [gt1r_signal_photons_delta_time = 0..69380]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt1r/signal_photons/delta_time
gt2l_signal_photons_delta_time: Array of 64 bit Reals [gt2l_signal_photons_delta_time = 0..2874]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt2l/signal_photons/delta_time
gt2r_land_segments_delta_time: Array of 64 bit Reals [gt2r_land_segments_delta_time = 0..77]
units: seconds since 2018-01-01
long_name: mean_pass_time
standard_name: time
description: Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Land ATBD section 2.4
coordinates: latitude longitude
origname: delta_time
fullnamepath: /gt2r/land_segments/delta_time
gt2r_signal_photons_delta_time: Array of 64 bit Reals [gt2r_signal_photons_delta_time = 0..14712]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt2r/signal_photons/delta_time
gt3l_signal_photons_delta_time: Array of 64 bit Reals [gt3l_signal_photons_delta_time = 0..1861]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt3l/signal_photons/delta_time
gt3r_land_segments_delta_time: Array of 64 bit Reals [gt3r_land_segments_delta_time = 0..24]
units: seconds since 2018-01-01
long_name: mean_pass_time
standard_name: time
description: Mean time for the segment in number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: Land ATBD section 2.4
coordinates: latitude longitude
origname: delta_time
fullnamepath: /gt3r/land_segments/delta_time
gt3r_signal_photons_delta_time: Array of 64 bit Reals [gt3r_signal_photons_delta_time = 0..5879]
units: seconds since 2018-01-01
long_name: delta time
standard_name: time
description: Number of GPS seconds since the ATLAS SDP epoch. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: ATL03
origname: delta_time
fullnamepath: /gt3r/signal_photons/delta_time
orbit_info_crossing_time: Array of 64 bit Reals [orbit_info_crossing_time = 0..0]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: Ascending Node Crossing Time
standard_name: time
description: The time, in seconds since the ATLAS SDP GPS Epoch, at which the ascending node crosses the equator. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: POD/PPD
origname: crossing_time
fullnamepath: /orbit_info/crossing_time
orbit_info_sc_orient_time: Array of 64 bit Reals [orbit_info_sc_orient_time = 0..0]
units: seconds since 2018-01-01
contentType: referenceInformation
long_name: Time of Last Spacecraft Orientation Change
standard_name: time
description: The time of the last spacecraft orientation change between forward, backward and transitional flight modes, expressed in seconds since the ATLAS SDP GPS Epoch. ICESat-2 is considered to be flying forward when the weak beams are leading the strong beams; and backward when the strong beams are leading the weak beams. ICESat-2 is considered to be in transition while it is maneuvering between the two orientations. Science quality is potentially degraded while in transition mode. The ATLAS Standard Data Products (SDP) epoch offset is defined within /ancillary_data/atlas_sdp_gps_epoch as the number of GPS seconds between the GPS epoch (1980-01-06T00:00:00.000000Z UTC) and the ATLAS SDP epoch. By adding the offset contained within atlas_sdp_gps_epoch to delta time parameters, the time in gps_seconds relative to the GPS epoch can be computed.
source: POD/PPD
origname: sc_orient_time
fullnamepath: /orbit_info/sc_orient_time
FakeDim0: Array of 32 bit Integers [FakeDim0 = 0..0]
units: level