1
referenceInformation
Metrics
Dimension scale for metrics.
metrics1 metrics2 metrics3 metrics4 metrics5 metrics6 metrics7 metrics8 metrics9
1
2
3
4
5
6
7
8
9
1
4
1
auxiliaryInformation
Surface Type Dimension Scale
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
land ocean seaice landice inland_water
1
2
3
4
5
1
5
ATL08
ATL08
3A
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
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)
Instrument Engineer, Investigator, Principle Investigator, Data Producer, Data Producer
CF-1.6
UTC
trajectory
degrees_north
degrees_east
10.5067/ATLAS/ATL08.001
http://dx.doi.org
ATL08
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.
http://dx.doi.org
Horizontal
CF-1.6
CCSDS UTC-A
2019-08-22T21:07:29.000000Z
HDF5 1.10.3
2019-08-22T21:07:29.000000Z;58383667-e9b3-3639-a8de-168784ceb5e9;Created by PGE atlas_l3a_ld Version 3.2
58383667-e9b3-3639-a8de-168784ceb5e9
3.2
461.
2018-10-16T12:54:37.000000Z
2018-10-16T12:46:56.000000Z
-78.804759009697463
-153.81953845733065
-78.498235427544756
-153.32549412458567
NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center
nsidc@nsidc.org
http://nsidc.org/daac/
ATLAS/ICESat-2 L3A Land and Vegetation Height
ATL08
National Aeronautics and Space Administration (NASA)
GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System
The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics.
EARTH SCIENCE > BIOSPHERE > VEGETATION > NONE > NONE > NONE > NONE
NASA/GCMD Science Keywords
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.
3A
http://nsidc.org/data/icesat2/data.html
ICESat-2 > Ice, Cloud, and land Elevation Satellite-2
ATLAS > Advanced Topographic Laser Altimeter System
ICESat-2 > Ice, Cloud, and land Elevation Satellite-2
Spacecraft
seconds since 2018-01-01
referenceInformation
Ascending Node Crossing Time
time
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.
POD/PPD
seconds since 2018-01-01
referenceInformation
Time of Last Spacecraft Orientation Change
time
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.
POD/PPD
1
referenceInformation
Orbit Number
Unique identifying number for each planned ICESat-2 orbit.
Operations
crossing_time
1
65000
degrees_east
referenceInformation
Ascending Node Longitude
Longitude at the ascending node crossing.
POD/PPD
crossing_time
-180.
180.
1
referenceInformation
Spacecraft Orientation
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.
POD/PPD
sc_orient_time
backward forward transition
0
1
2
0
2
1
referenceInformation
Reference Ground track
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.
POD/PPD
crossing_time
1
1387
1
referenceInformation
Cycle Number
A count of the number of exact repeats of this reference orbit.
Operations
crossing_time
0
50
Contains orbit information.
Varies. Data are only provided when one of the stored values (besides time) changes.
ISO19115 Structured Metadata Represented within HDF5
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<gmd:contactInfo xlink:href="#NSIDC_DAAC_CONTACT_ID"/>
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10000 pps
532 nm
ATLAS
Laser Altimeter
ATLAS on ICESat-2 determines the range between the satellite and the Earth's surface by measuring the two-way time delay of short pulses of laser light that it transmits in six beams. It is different from previous operational ice-sheet altimeters in that it is a photon-counting LIDAR. ATLAS records a set of arrival times for individual photons, which are then analyzed to derive surface, vegetation, and cloud properties. ATLAS has six beams arranged in three pairs, so that it samples each of three reference pair tracks with a pair of beams; ATLAS transmits pulses at 10 kHz, giving approximately one pulse every 0.7 m along track; ATLAS's expected pointing control will be better than 90 m RMS.
Pre-Release
12/31/17
A document describing the ATLAS instrument will be provided by the ICESat-2 Project Science Office.
ICESat-2
Ice, Cloud, and land Elevation Satellite-2
Spacecraft
31-Dec-16
31-Dec-16
The Ice, Cloud, and land Elevation Satellite-2 (ICESat-2): Science requirements, concept, and implementation. Thorsten Markus, Tom Neumann, Anthony Martino, Waleed Abdalati, Kelly Brunt, Beata Csatho, Sinead Farrell, Helen Fricker, Alex Gardner, David Harding, Michael Jasinski, Ron Kwok, Lori Magruder, Dan Lubin, Scott Luthcke, James Morison, Ross Nelson, Amy Neuenschwander, Stephen Palm, Sorin Popescu, CK Shum, Bob E. Schutz, Benjamin Smith, Yuekui Yang, Jay Zwally. http://dx.doi.org/10.1016/j.rse.2016.12.029
NOT_SET
directInternal
TBD
TBD
TBD
NOT_SET
directInternal
TBD
TBD
TBD
NOT_SET
utf8
F
eng
07/2019
ATL08_SDP
ICESat-2-SIPS-SPEC-4262 - ATLAS Science Algorithm Standard Data Product (SDP) Volume 7 (ATL08).
asNeeded
SET_BY_META
002
10.5067/ATLAS/ATL08.001
eng
utf8
NSIDC DAAC > NASA National Snow and Ice Data Center Distributed Active Archive Center
ATLAS/ICESat-2 L3A Land and Vegetation Height
ATL08
2016-06-09
National Aeronautics and Space Administration (NASA)
The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance.
The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics.
The software that generates the ATL08 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland.
onGoing
HDF
5
geoscientificInformation
ICESat-2 > Ice, Cloud, and land Elevation Satellite-2
along-track
2019-08-22T21:07:29.000000Z
58383667-e9b3-3639-a8de-168784ceb5e9
ATL08_20181016124656_02730110_002_01.h5
002
eng
utf8
ATL08
GSFC I-SIPS > ICESat-2 Science Investigator-led Processing System
The ICESat-2 ATL08 standard data product contains along-track heights of ground and canopy surface at varying length scales. Where data permits, this includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect, and apparent reflectance.
The purpose of ATL08 is to provide along-track land/canopy heights and associated statistics.
The software that generates the ATL08 product was designed and implemented within the ICESat-2 Science Investigator-led Processing System at the NASA Goddard Space Flight Center in Greenbelt, Maryland.
onGoing
geoscientificInformation
-78.498235427544756
-153.32549412458567
-78.804759009697463
-153.81953845733065
2018-10-16T12:54:26.671899Z
2018-10-16T12:54:31.250499Z
An ASCII product that contains statistical information on data product results. These statistics enable data producers and users to assess the quality of the data in the data product granule
2019-08-22T21:08:14.000000Z
ATL08_20181016124656_02730110_002_01.qa
Text-based keyword=value file generated automatically within the ICESat-2 data system that specifies all of the conditions required for each individual run of the software.
CTL_atlas_l3a_ld_000081470.ctl
CNTL
1
DTU Mean Sea Surface re-referenced to the WGS84 ellipsoid.
dtu13_20180705_001_01.nc
ANC28
56f47040-a72e-3109-99c2-bc1658e6dda4
20180705
Landsat Canopy Mask File
ANC14
ArcticDEM 32m Digital Elevation Model reformatted into HDF5.
arcticdem32m_20190611_001_01.h5
ANC06-02
ce07ef72-0bf4-353b-8475-fb568b029905
20190611
REMA Antarctica 100m Digital Elevation Model filled and reformatted into HDF5
atl06rema100m_20190628_001_01.h5
ANC06-03
3e0a81bd-bbd5-35fa-b868-3254f9355b7f
20190628
HDF5 template file that defines the organization and default content of the product.
atl08_template.h5
ANC25-08
1d66a513-7f12-3239-bbb1-09e62031feec
032
Water Mask File
watermask_2000_20180301_001_global.h5
ANC33
1e7d3697-c576-308d-9197-21d827ac21db
20180301
Modis Land Cover Mask File
glcc_2012_20180226_001_global.h5
ANC18
46e34ac9-892a-3a9d-ab7e-6a329e167a1a
20180226
ISO 19139 XML file containing DataSet-level metadata information.
ATL08.002.dataset.xml
ANC38-08
55e7a88e-6258-3bc1-844a-458ba3a595fc
002
Urban Mask File
SET_BY_PGE
SET_BY_PGE
SET_BY_PGE
SET_BY_PGE
ICESat-2 ATLAS L2A Global Geolocated Photon data products.
ATL03_20181016124656_02730110_002_01.h5
ATL03
5afc3dc0-33ba-335b-b3bb-2cc34e7c4cd5
002
1
1
474
474
273
273
10
10
1280110
1443604
ICESat-2 ATLAS L3A atmosphere data products.
ATL09_20181016114648_02730101_002_01.h5
ATL09
0392edf6-cdc4-3c42-9ee7-12c7c38d14af
002
1
1
474
474
273
273
1
14
19
2007126
GMTED 7.5 arcsec Digital Elevation Model reformatted into HDF5 and re-referenced to the WGS-84 ellipsoid.
gmted75_20180705_001_01.h5
ANC06-01
a44debc8-29af-3744-860c-227b37a4da6f
20180705
HDF5 template file that defines the organization and default content of the product metadata.
atl08_metadata_template.h5
ANC26-08
f2d4b804-5f00-388c-80ba-9c45b0f9aecf
032
TAI to UTC leapsecond file retrieved from ftp://maia.usno.navy.mil/ser7/tai-utc.dat
tai_utc_2017.dat
ANC19
a5c65112-d05e-3263-83cd-a36f1a81acdf
001
ISO 19139 XML file containing Series-level metadata information.
ATL08.002.series.xml
ANC36-08
87849aa9-407f-3fec-9f8b-46f45b818b5e
002
Browse processing is performed for each granule SIPS produces. The browse utility reads data from the granule and produces browse images as defined in the respective product ATBD. The utility then embeds each browse image into the product within the /Browse group.
atlas_brw
Version 2.2
Jul 31 2019
Creates ATLAS HDF5 browse files
CTL_atlas_l3a_ld_000081470.ctl
2019-08-22T21:08:14.000000Z
Metadata information is processed by the metadata utility for each granule produced by SIPS. During PGE processing, dynamic metadata are written to the product. Additional static information is provided with the metadata template. The metadata utility reads ISO Dataset and Series metadata files and updates the product with static information from within those files. The utility then merges the static and dynamic metadata to creates output ISO19139 Dataset and Series XML files. Finally the utility reads the ISO19139 Dataset and Series XML files into memory and stores the textual representations as attributes attached to the /METADATA group.
atlas_meta
Version 4.2
Jul 31 2019
Creates ATLAS XML metadata files
CTL_atlas_l3a_ld_000081470.ctl
2019-08-22T21:08:21.000000Z
11/1/17
ICESat-2-SIPS-SPEC-1608 - SIPs: Land, Vegetation, and Inland Water L5 Specification Document
2017 November
ICESat-2-SIPS-SPEC-2331 - ATLAS Science Algorithm Software Design Description (SDD) Volume 12 (atlas_l3a_ld). Revision B.
12/1/17
Determines heights of ground and canopy surface. Where data permits, includes estimates of canopy height, relative canopy cover, canopy height distributions, surface roughness, surface slope/aspect and apparent reflectance.
atlas_l3a_ld
Version 3.2
Jul 31 2019
ASAS L3A Land PGE
CTL_atlas_l3a_ld_000081470.ctl
2019-08-22T21:07:29.000000Z
QA processing is performed by an external utility on each granule produced by SIPS. The utility reads the granule, performs both generic and product-specific quality-assessment calculations, and writes a text-based quality assessment report. The name and creation data of this report are identified within the QADatasetIdentification metadata
atl08_qa_util
Version 3.2
Jul 31 2019
ATL08 QA Utility
CTL_atlas_l3a_ld_000081470.ctl
2019-08-22T21:08:14.000000Z
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce3
strong
gt1r
profile_1
5
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
degrees
latitude
latitude
Latitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time longitude
-90.
90.
seconds since 2018-01-01
mean_pass_time
time
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.
Land ATBD section 2.4
latitude longitude
1
referenceInformation
reference ground track
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.
Operations
delta_time latitude longitude
1
1387
127
1
referenceInformation
dem source flag
Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
Atmosphere ATBD
delta_time latitude longitude
none arctic gmted mss antarctic
0
1
2
3
4
0
4
127
1
multiple scattering warning flag
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.
ATL09
delta_time latitude longitude
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
-1
0
1
2
3
4
5
127
1
cloud flag atm
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.
ATL09
delta_time latitude longitude
0
10
3.402823466e+38
1
signal to noise ratio
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.
ATBD section 2.5.14
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas y
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.
ATL03
delta_time latitude longitude
modelResult
consolidated cloud flag
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.
ATL09
delta_time latitude longitude
likely_clear likely_cloudy
0
1
127
1
segment snowcover
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.
ATBD section 4.2.16
delta_time latitude longitude
ice_free_water snow_free_land snow ice
0
1
2
3
0
3
3.402823466e+38
radians
referenceInformation
beam azimuth
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.
ATL03
delta_time latitude longitude
degrees_east
referenceInformation
solar azimuth
The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
ATL03g ATBD
delta_time latitude longitude
1
referenceInformation
point spread function flag
Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
Land/Veg ATBD
delta_time latitude longitude
below_threshold above_threshold
0
1
0
1
degrees
longitude
longitude
Longitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time latitude
-180.
180.
255
1
segment watermask
Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
ATBD section 2.4.15
delta_time latitude longitude
no_water water
0
1
0
1
1
referenceInformation
end geolocation segment bin
Geolocation segment number of the last photon in the land segment.
ATL03
delta_time latitude longitude
1
referenceInformation
surface type
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.
ATL03 ATBD, Section 4
delta_time latitude longitude
not_type is_type
0
1
0
1
127
1
brightness flag
Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
Land ATBD section 2.4.21
delta_time latitude longitude
not_bright_surface bright_surface
0
1
255
1
segment landcover
IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
ATBD section 2.4.14
delta_time latitude longitude
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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
16
1
ph removal flag
Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
ATBD section 4.13
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
1
apparent surface reflectance
Apparent surface reflectance
ATL09
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas land
Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
Land ATBD section 2.5.13
delta_time latitude longitude
1
referenceInformation
begin geolocation segment bin
Geolocation segment number of the first photon in the land segment.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas x
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.
ATL03
delta_time latitude longitude
3.402823466e+38
meters
referenceInformation
dem height
Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
GIMP, GMTED,MSS
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
beam co-elevation
Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas topo
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.
Land ATBD section 2.5.12
delta_time latitude longitude
2147483647
1
night flag
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.
Land ATBD section 2.4.8
delta_time latitude longitude
day night
0
1
seconds since 2018-01-01
referenceInformation
delta time begin
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
referenceInformation
height uncertainty
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.
ATL03
delta_time latitude longitude
3.402823466e+38
1
kilometers
last segment extended
last_seg_extend
The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
Land ATBD 13March2019, Section 2.4.20
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
atlas pointing angle
Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
ATL03
delta_time latitude longitude
1
photon index begin
Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment.
Derived
delta_time latitude longitude
degrees
referenceInformation
solar elevation
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.
ATL03g ATBD
delta_time latitude longitude
seconds since 2018-01-01
referenceInformation
delta time end
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
127
modelResult
cloud folding flag
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.
ATL09
delta_time latitude longitude
no_folding goes5_indicates profile_indicates both_indicate
0
1
2
3
0
3
1
number of photons
Number of photons within each land segment.
Derived
delta_time latitude longitude
2147483647
1
terrain flag
Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
Land ATBD section 2.4.8
delta_time latitude longitude
below_threshold above_threshold
0
1
2147483647
1
segment urban flag
The urban flag indicates that a segment is likely located over an urban area.
Land ATBD section 2.4.17
delta_time latitude longitude
not_urban urban
0
1
1
dem removal flag
Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
ATBD section 2.4.11
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
meters
h dif from reference
Difference between h_te_median and ref_DEM
Land ATBD section 2.4
delta_time latitude longitude
Contains data categorized as land at 100 meter intervals.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
height canopy
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
1
modelResult
canopy relative height confidence
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).
Land/Veg ATBD 13March2019, Section 2.2.21
../delta_time ../latitude ../longitude
<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
0
1
2
0
2
3.402823466e+38
meters
absolute segment median canopy height
The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.6
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum canopy height
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.
Land ATBD section 2.2.10
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute mean canopy height
Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.4
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median canopy height
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.
Land ATBD section 2.2.8
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute segment canopy height
The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.2
../delta_time ../latitude ../longitude
3.402823466e+38
meters
top of canopy roughness
Standard deviation of the relative heights of all photons classified as top of canopy within the segment
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute minimum canopy height
The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy diff to median height
Difference between h_canopy and h_median_canopy
Land ATBD section 4.12
../delta_time ../latitude ../longitude
canopy quadratic mean
The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
1
number canopy photons
The number of photons classified as canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
centroid height
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
canopy absolute height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
landsat percentage canopy
Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
Land ATBD section 2.2.24
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean canopy height
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
1
number top of canopy photons
The number of photons classified as top of canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
2147483647
1
canopy flag
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
no_canopy_present canopy_present
0
1
2147483647
1
landsat flag
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.
Land ATBD section 2.2.25
../delta_time ../latitude ../longitude
canopy_not_assumed_present canopy_assumed_present
0
1
3.402823466e+38
meters
absolute maximum canopy height
Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment canopy height uncertainty
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
Land ATBD section 1.5
../delta_time ../latitude ../longitude
3.402823466e+38
1
canopy openness
Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum canopy height
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.
Land ATBD section 2.2.12
../delta_time ../latitude ../longitude
Contains height parameters based on the land algorithm.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
uncertainty of h_te_mean
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
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean terrain height
The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum terrain height
The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
interpolated terrain surface height
Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
Land ATBD section 4.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum terrain height
The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
skew of terrain heights
The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median terrain height
The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment terrain height best fit
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.
Land ATBD section 2.1.15
../delta_time ../latitude ../longitude
segment terrain roughness
The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
segment terrain slope
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.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
1
number of ground photons
The number of the photons classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mode of terrain heights
The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
Contains terrain parameters at a 100m aggregation.
Data are stored as aggregates of 100 meters.
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce2
strong
gt2r
profile_2
3
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
degrees
latitude
latitude
Latitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time longitude
-90.
90.
seconds since 2018-01-01
mean_pass_time
time
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.
Land ATBD section 2.4
latitude longitude
1
referenceInformation
reference ground track
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.
Operations
delta_time latitude longitude
1
1387
127
1
referenceInformation
dem source flag
Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
Atmosphere ATBD
delta_time latitude longitude
none arctic gmted mss antarctic
0
1
2
3
4
0
4
127
1
multiple scattering warning flag
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.
ATL09
delta_time latitude longitude
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
-1
0
1
2
3
4
5
127
1
cloud flag atm
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.
ATL09
delta_time latitude longitude
0
10
3.402823466e+38
1
signal to noise ratio
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.
ATBD section 2.5.14
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas y
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.
ATL03
delta_time latitude longitude
modelResult
consolidated cloud flag
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.
ATL09
delta_time latitude longitude
likely_clear likely_cloudy
0
1
127
1
segment snowcover
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.
ATBD section 4.2.16
delta_time latitude longitude
ice_free_water snow_free_land snow ice
0
1
2
3
0
3
3.402823466e+38
radians
referenceInformation
beam azimuth
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.
ATL03
delta_time latitude longitude
degrees_east
referenceInformation
solar azimuth
The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
ATL03g ATBD
delta_time latitude longitude
1
referenceInformation
point spread function flag
Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
Land/Veg ATBD
delta_time latitude longitude
below_threshold above_threshold
0
1
0
1
degrees
longitude
longitude
Longitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time latitude
-180.
180.
255
1
segment watermask
Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
ATBD section 2.4.15
delta_time latitude longitude
no_water water
0
1
0
1
1
referenceInformation
end geolocation segment bin
Geolocation segment number of the last photon in the land segment.
ATL03
delta_time latitude longitude
1
referenceInformation
surface type
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.
ATL03 ATBD, Section 4
delta_time latitude longitude
not_type is_type
0
1
0
1
127
1
brightness flag
Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
Land ATBD section 2.4.21
delta_time latitude longitude
not_bright_surface bright_surface
0
1
255
1
segment landcover
IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
ATBD section 2.4.14
delta_time latitude longitude
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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
16
1
ph removal flag
Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
ATBD section 4.13
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
1
apparent surface reflectance
Apparent surface reflectance
ATL09
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas land
Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
Land ATBD section 2.5.13
delta_time latitude longitude
1
referenceInformation
begin geolocation segment bin
Geolocation segment number of the first photon in the land segment.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas x
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.
ATL03
delta_time latitude longitude
3.402823466e+38
meters
referenceInformation
dem height
Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
GIMP, GMTED,MSS
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
beam co-elevation
Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas topo
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.
Land ATBD section 2.5.12
delta_time latitude longitude
2147483647
1
night flag
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.
Land ATBD section 2.4.8
delta_time latitude longitude
day night
0
1
seconds since 2018-01-01
referenceInformation
delta time begin
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
referenceInformation
height uncertainty
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.
ATL03
delta_time latitude longitude
3.402823466e+38
1
kilometers
last segment extended
last_seg_extend
The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
Land ATBD 13March2019, Section 2.4.20
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
atlas pointing angle
Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
ATL03
delta_time latitude longitude
1
photon index begin
Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment.
Derived
delta_time latitude longitude
degrees
referenceInformation
solar elevation
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.
ATL03g ATBD
delta_time latitude longitude
seconds since 2018-01-01
referenceInformation
delta time end
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
127
modelResult
cloud folding flag
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.
ATL09
delta_time latitude longitude
no_folding goes5_indicates profile_indicates both_indicate
0
1
2
3
0
3
1
number of photons
Number of photons within each land segment.
Derived
delta_time latitude longitude
2147483647
1
terrain flag
Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
Land ATBD section 2.4.8
delta_time latitude longitude
below_threshold above_threshold
0
1
2147483647
1
segment urban flag
The urban flag indicates that a segment is likely located over an urban area.
Land ATBD section 2.4.17
delta_time latitude longitude
not_urban urban
0
1
1
dem removal flag
Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
ATBD section 2.4.11
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
meters
h dif from reference
Difference between h_te_median and ref_DEM
Land ATBD section 2.4
delta_time latitude longitude
Contains data categorized as land at 100 meter intervals.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
height canopy
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
1
modelResult
canopy relative height confidence
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).
Land/Veg ATBD 13March2019, Section 2.2.21
../delta_time ../latitude ../longitude
<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
0
1
2
0
2
3.402823466e+38
meters
absolute segment median canopy height
The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.6
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum canopy height
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.
Land ATBD section 2.2.10
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute mean canopy height
Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.4
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median canopy height
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.
Land ATBD section 2.2.8
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute segment canopy height
The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.2
../delta_time ../latitude ../longitude
3.402823466e+38
meters
top of canopy roughness
Standard deviation of the relative heights of all photons classified as top of canopy within the segment
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute minimum canopy height
The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy diff to median height
Difference between h_canopy and h_median_canopy
Land ATBD section 4.12
../delta_time ../latitude ../longitude
canopy quadratic mean
The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
1
number canopy photons
The number of photons classified as canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
centroid height
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
canopy absolute height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
landsat percentage canopy
Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
Land ATBD section 2.2.24
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean canopy height
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
1
number top of canopy photons
The number of photons classified as top of canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
2147483647
1
canopy flag
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
no_canopy_present canopy_present
0
1
2147483647
1
landsat flag
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.
Land ATBD section 2.2.25
../delta_time ../latitude ../longitude
canopy_not_assumed_present canopy_assumed_present
0
1
3.402823466e+38
meters
absolute maximum canopy height
Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment canopy height uncertainty
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
Land ATBD section 1.5
../delta_time ../latitude ../longitude
3.402823466e+38
1
canopy openness
Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum canopy height
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.
Land ATBD section 2.2.12
../delta_time ../latitude ../longitude
Contains height parameters based on the land algorithm.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
uncertainty of h_te_mean
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
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean terrain height
The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum terrain height
The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
interpolated terrain surface height
Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
Land ATBD section 4.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum terrain height
The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
skew of terrain heights
The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median terrain height
The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment terrain height best fit
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.
Land ATBD section 2.1.15
../delta_time ../latitude ../longitude
segment terrain roughness
The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
segment terrain slope
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.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
1
number of ground photons
The number of the photons classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mode of terrain heights
The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
Contains terrain parameters at a 100m aggregation.
Data are stored as aggregates of 100 meters.
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce3
weak
gt1l
profile_1
6
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
degrees
latitude
latitude
Latitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time longitude
-90.
90.
seconds since 2018-01-01
mean_pass_time
time
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.
Land ATBD section 2.4
latitude longitude
1
referenceInformation
reference ground track
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.
Operations
delta_time latitude longitude
1
1387
127
1
referenceInformation
dem source flag
Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
Atmosphere ATBD
delta_time latitude longitude
none arctic gmted mss antarctic
0
1
2
3
4
0
4
127
1
multiple scattering warning flag
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.
ATL09
delta_time latitude longitude
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
-1
0
1
2
3
4
5
127
1
cloud flag atm
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.
ATL09
delta_time latitude longitude
0
10
3.402823466e+38
1
signal to noise ratio
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.
ATBD section 2.5.14
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas y
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.
ATL03
delta_time latitude longitude
modelResult
consolidated cloud flag
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.
ATL09
delta_time latitude longitude
likely_clear likely_cloudy
0
1
127
1
segment snowcover
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.
ATBD section 4.2.16
delta_time latitude longitude
ice_free_water snow_free_land snow ice
0
1
2
3
0
3
3.402823466e+38
radians
referenceInformation
beam azimuth
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.
ATL03
delta_time latitude longitude
degrees_east
referenceInformation
solar azimuth
The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
ATL03g ATBD
delta_time latitude longitude
1
referenceInformation
point spread function flag
Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
Land/Veg ATBD
delta_time latitude longitude
below_threshold above_threshold
0
1
0
1
degrees
longitude
longitude
Longitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time latitude
-180.
180.
255
1
segment watermask
Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
ATBD section 2.4.15
delta_time latitude longitude
no_water water
0
1
0
1
1
referenceInformation
end geolocation segment bin
Geolocation segment number of the last photon in the land segment.
ATL03
delta_time latitude longitude
1
referenceInformation
surface type
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.
ATL03 ATBD, Section 4
delta_time latitude longitude
not_type is_type
0
1
0
1
127
1
brightness flag
Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
Land ATBD section 2.4.21
delta_time latitude longitude
not_bright_surface bright_surface
0
1
255
1
segment landcover
IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
ATBD section 2.4.14
delta_time latitude longitude
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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
16
1
ph removal flag
Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
ATBD section 4.13
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
1
apparent surface reflectance
Apparent surface reflectance
ATL09
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas land
Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
Land ATBD section 2.5.13
delta_time latitude longitude
1
referenceInformation
begin geolocation segment bin
Geolocation segment number of the first photon in the land segment.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas x
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.
ATL03
delta_time latitude longitude
3.402823466e+38
meters
referenceInformation
dem height
Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
GIMP, GMTED,MSS
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
beam co-elevation
Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas topo
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.
Land ATBD section 2.5.12
delta_time latitude longitude
2147483647
1
night flag
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.
Land ATBD section 2.4.8
delta_time latitude longitude
day night
0
1
seconds since 2018-01-01
referenceInformation
delta time begin
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
referenceInformation
height uncertainty
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.
ATL03
delta_time latitude longitude
3.402823466e+38
1
kilometers
last segment extended
last_seg_extend
The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
Land ATBD 13March2019, Section 2.4.20
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
atlas pointing angle
Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
ATL03
delta_time latitude longitude
1
photon index begin
Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment.
Derived
delta_time latitude longitude
degrees
referenceInformation
solar elevation
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.
ATL03g ATBD
delta_time latitude longitude
seconds since 2018-01-01
referenceInformation
delta time end
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
127
modelResult
cloud folding flag
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.
ATL09
delta_time latitude longitude
no_folding goes5_indicates profile_indicates both_indicate
0
1
2
3
0
3
1
number of photons
Number of photons within each land segment.
Derived
delta_time latitude longitude
2147483647
1
terrain flag
Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
Land ATBD section 2.4.8
delta_time latitude longitude
below_threshold above_threshold
0
1
2147483647
1
segment urban flag
The urban flag indicates that a segment is likely located over an urban area.
Land ATBD section 2.4.17
delta_time latitude longitude
not_urban urban
0
1
1
dem removal flag
Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
ATBD section 2.4.11
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
meters
h dif from reference
Difference between h_te_median and ref_DEM
Land ATBD section 2.4
delta_time latitude longitude
Contains data categorized as land at 100 meter intervals.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
height canopy
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
1
modelResult
canopy relative height confidence
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).
Land/Veg ATBD 13March2019, Section 2.2.21
../delta_time ../latitude ../longitude
<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
0
1
2
0
2
3.402823466e+38
meters
absolute segment median canopy height
The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.6
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum canopy height
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.
Land ATBD section 2.2.10
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute mean canopy height
Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.4
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median canopy height
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.
Land ATBD section 2.2.8
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute segment canopy height
The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.2
../delta_time ../latitude ../longitude
3.402823466e+38
meters
top of canopy roughness
Standard deviation of the relative heights of all photons classified as top of canopy within the segment
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute minimum canopy height
The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy diff to median height
Difference between h_canopy and h_median_canopy
Land ATBD section 4.12
../delta_time ../latitude ../longitude
canopy quadratic mean
The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
1
number canopy photons
The number of photons classified as canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
centroid height
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
canopy absolute height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
landsat percentage canopy
Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
Land ATBD section 2.2.24
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean canopy height
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
1
number top of canopy photons
The number of photons classified as top of canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
2147483647
1
canopy flag
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
no_canopy_present canopy_present
0
1
2147483647
1
landsat flag
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.
Land ATBD section 2.2.25
../delta_time ../latitude ../longitude
canopy_not_assumed_present canopy_assumed_present
0
1
3.402823466e+38
meters
absolute maximum canopy height
Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment canopy height uncertainty
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
Land ATBD section 1.5
../delta_time ../latitude ../longitude
3.402823466e+38
1
canopy openness
Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum canopy height
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.
Land ATBD section 2.2.12
../delta_time ../latitude ../longitude
Contains height parameters based on the land algorithm.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
uncertainty of h_te_mean
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
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean terrain height
The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum terrain height
The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
interpolated terrain surface height
Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
Land ATBD section 4.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum terrain height
The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
skew of terrain heights
The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median terrain height
The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment terrain height best fit
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.
Land ATBD section 2.1.15
../delta_time ../latitude ../longitude
segment terrain roughness
The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
segment terrain slope
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.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
1
number of ground photons
The number of the photons classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mode of terrain heights
The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
Contains terrain parameters at a 100m aggregation.
Data are stored as aggregates of 100 meters.
1
qualityInformation
Granule Failure Reason
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.
Operations
no_failure PROCESS_ERROR INSUFFICIENT_OUTPUT failure_3 failure_4 OTHER_FAILURE
0
1
2
3
4
5
0
5
1
qualityInformation
Granule Pass Flag
Flag indicating granule quality. 0=granule passes automatic QA. 1=granule fails automatic QA.
Operations
PASS FAIL
0
1
0
1
Contains quality assessment data. This may include QA counters, QA along-track data and/or QA summary data.
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce1
weak
gt3l
profile_3
2
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce2
weak
gt2l
profile_2
4
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
1
auxiliaryInformation
Release Number
Release number of the granule. The release number is incremented when the software or ancillary data used to create the granule has been changed.
Operations
1
auxiliaryInformation
Ending Geolocation Segment
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.
Derived
1
auxiliaryInformation
Version
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.
Operations
1
auxiliaryInformation
Ending Region
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.
Derived
seconds since 1980-01-06T00:00:00.000000Z
auxiliaryInformation
ATLAS Epoch Offset
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.
Operations
1
auxiliaryInformation
Ending Reference Groundtrack
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.
Derived
1
1387
seconds since 2018-01-01
auxiliaryInformation
ATLAS End Time (Actual)
time
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.
Derived
1
auxiliaryInformation
Ending Orbit Number
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.
Derived
1
auxiliaryInformation
Starting Cycle
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.
Derived
0
99
1
auxiliaryInformation
End UTC Time of Granule (CCSDS-A, Actual)
UTC (in CCSDS-A format) of the last data point within the granule.
Derived
1
auxiliaryInformation
Control File
PGE-specific control file used to generate this granule. To re-use, replace breaks (BR) with linefeeds.
Operations
seconds
auxiliaryInformation
Start GPS SOW of Granule (Actual)
GPS seconds-of-week of the first data point in the granule.
Derived
1
auxiliaryInformation
End UTC Time of Granule (CCSDS-A, Requested)
Requested end time (in UTC CCSDS-A) of this granule.
Derived
1
auxiliaryInformation
Ending Cycle
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.
Derived
0
99
1
auxiliaryInformation
Start UTC Time of Granule (CCSDS-A, Requested)
Requested start time (in UTC CCSDS-A) of this granule.
Derived
seconds since 2018-01-01
auxiliaryInformation
ATLAS Start Time (Actual)
time
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.
Derived
1
auxiliaryInformation
Starting Geolocation Segment
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.
Derived
1
auxiliaryInformation
Starting Orbit Number
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.
Derived
1
auxiliaryInformation
Start UTC Time of Granule (CCSDS-A, Actual)
UTC (in CCSDS-A format) of the first data point within the granule.
Derived
weeks from 1980-01-06
auxiliaryInformation
Ending GPSWeek of Granule (Actual)
GPS week number of the last data point in the granule.
Derived
1
auxiliaryInformation
Starting Reference Groundtrack
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.
Derived
1
1387
seconds
auxiliaryInformation
Ending GPS SOW of Granule (Actual)
GPS seconds-of-week of the last data point in the granule.
Derived
1
auxiliaryInformation
QA Along-Track Interval
Statistics time interval for along-track QA data.
control
1
auxiliaryInformation
Starting Region
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.
Derived
weeks from 1980-01-06
auxiliaryInformation
Start GPSWeek of Granule (Actual)
GPS week number of the first data point in the granule.
Derived
Contains information ancillary to the data product. This may include product characteristics, instrument characteristics and/or processing constants.
Data within this group pertain to the granule in its entirety.
1
auxiliaryInformation
Canopy classification flag value. (Default = 2)
ATBD section 4.12 step 1
Canopy class value
1
auxiliaryInformation
Controls entrance to the canopy flag subroutine . (Default = 1)
ATBD section 4.3
canopy_flag switch
meters
auxiliaryInformation
Upper bound restricting the search of a top of canopy surface.
Upper bound restricting the search of a top of canopy surface. (Default=1.0)
ATBD section 4.7 step 3 entered from section 4.8
1
auxiliaryInformation
finalground filter switch
Controls filtering based on FINALGROUND. (Default = 1)
ATBD section 4.13 step 2
meters
auxiliaryInformation
Point Spread Function
Parameter controlling identification of photons around an interpolated surface. (Default = 0.5)
ATBD section 4.7 step 12
percent
auxiliaryInformation
dem_removal_flag set threshold
Percent of photons in land segment failing DEM test to set dem_removal_flag. (default = 20.0)
ATBD section 2.4.11
1
modelResult
atl08 region
atl08_region
ATL08 region(s) encompassed by ATL03 granule being processed
Land ATBD 29March2019, Table 2.4
1
auxiliaryInformation
Threshold for reclassification of canopy as noise
Threshold, as a number of canopy photons in the CAN_FILT_SEG, used for the reclassification of canopy signal photons. (Default = 75)
ATBD section 4.11 step 6
meters
auxiliaryInformation
lower relief percentile
The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.05)
ATBD (section 4.5 step 6)
1
auxiliaryInformation
dem_filter switch
Controls filtering based on DEM. (Default = 1)
ATBD section 4.5 step 5
meters
auxiliaryInformation
Upper relief percentile
The approximate relief of the L-km segment uses the percentile height values, relief_htop and relief_hbot. (Default=0.95)
ATBD (section 4.5 step 6)
1
auxiliaryInformation
DRAGANN segment buffer size
DRAGANN segment buffer length in 20m geolocated segments along ground track. (Default=10)
ATBD section 4.2.1 step 1
1
auxiliaryInformation
Threshold for night
Solar elevation threshold for determining night time conditions. (Default =0.0)
ATBD section 2.4.9
1
auxiliaryInformation
h_canopy percentile
Percentile component of h_canopy parameter. (Default =0.95)
ATBD section 2.2.3
1
auxiliaryInformation
Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons.
Lower bound of the filter window size function. (Default = 46)
ATBD section 4.4 step 2
1
auxiliaryInformation
Proportionality coefficient for controlling the bounds of the filter window size as a function of number of signal photons.
Lower bound of the filter window size function. (Default = 5)
ATBD section 4.4 step 2
percent
auxiliaryInformation
ph_removal_flag set threshold
Percent of photons in land segment removed to set ph_removal_flag. (default = 50.0)
ATBD section 4.13 step 4
1
auxiliaryInformation
segment size in canopy filter
Segment in number of signal photons for filtering sparse canopy cover. (Default = 500)
ATBD section 4.11 step 6
1
auxiliaryInformation
Maximum try count
Maximum number of tries to compute a P value in alternative DRAGANN
ATBD section 4.2.1 step 17
1
auxiliaryInformation
neighbor histogram bin size
Size of neighbor histogram bins in number of neighbors in DRAGANN. (Default = 1)
ATBD (section 4.2 step 4)
meters
auxiliaryInformation
Lower bound restricting the search of a ground surface in canopy cases.
Lower bound restricting the search of a ground surface in canopy cases. (Default = -4.0)
ATBD section 4.7 step 3
1
auxiliaryInformation
Step size for optimizing the mean parameter of Gaussian function.
Step size for optimizing the mean parameter of Gaussian function. (Default = 0.2)
ATBD section 4.2 step 7
meters
auxiliaryInformation
Lower cutoff for top of canopy
Lower cutoff for top of canopy surface. (Default = 2.0)
ATBD section 4.8 step 10
1
auxiliaryInformation
Threshold flag value for classification of photons as signal via input from ATL03
Threshold flag value for classification of photons as signal via input from ATL03. (Default =3)
ATBD section 4.2 step 17
1
auxiliaryInformation
Long segment buffer size
Overlapping long segment buffer size in 20m geosegments along ground track. (Default=10)
ATBD section 4.1 step 2
meters
auxiliaryInformation
Lower bound restricting the search of a top of canopy surface.
Lower bound restricting the search of a top of canopy surface. (Default = -4.0)
section 4.7 step 3 entered from section 4.8
meters
auxiliaryInformation
upper cutoff of top of canopy surface.
Upper cutoff for top of canopy surface. (Default = 150.0)
ATBD section 4.8 step 10
1
auxiliaryInformation
Threshold for terrain statistics
Minimum percentage of terrain photons to compute statistics upon. (Default =0.05)
ATBD section 4.13 step 2
1
auxiliaryInformation
Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram.
Maximum number of iterations for optimizing the Gaussian parameters for fitting of histogram. (Default = 10)
ATBD section 4.2 step 7
1
auxiliaryInformation
threshold for Gaussian Elimination
Controls threshold for Gaussian Elimination. (Default = 0.1)
ATBD sGaussian Rejection section of Appendix A
1
auxiliaryInformation
brightness flag average ph per shot
Threshold to set brightness_flag, average ground photons per shot. (Default = 3.0)
ATBD section 2.4.21
1
auxiliaryInformation
DRAGANN segment size
DRAGANN segment length in 20m geolocated segments along ground track. (Default=170)
ATBD section 4.2.1 step 1
1
auxiliaryInformation
neighbor histogram bin size
Histogram bin size for the alternative DRAGANN algorithm. (Default = 1.0)
ATBD (section 4.2.1 step 3)
meters
auxiliaryInformation
Upper bound restricting the search of a ground surface in canopy cases.
Upper bound restricting the search of a ground surface in canopy cases. (Default = 1.0)
ATBD (section 4.7 step 3)
1
auxiliaryInformation
Minimum input photons
Minimum number of input photons from ATL03 to process. (default=1)
Operations
1
auxiliaryInformation
Canopy Flag threshold
Percentage threshold for average L-km segment tree cover to be considered canopy. (Default = 5.0)
ATBD section 4.3 steps 6 and 7
1
auxiliaryInformation
Terrain class value
Terrain classification flag value. (Default = 1)
ATBD section 4.12 step 1
1
auxiliaryInformation
Top of canopy class value
Top of canopy classification flag value. (Default = 3)
ATBD section 4.12 step 1
1
auxiliaryInformation
Iterations of smoothing of interpolated ground surface for ground estimate.
Iterations of smoothing of interpolated ground surface for refinement. (Default = 10)
ATBD section 4.10 step 1
1
auxiliaryInformation
Maximum number of input ATL03s
Maximum number of input ATL03 files. (Default = 200)
Operations
1
auxiliaryInformation
Noise class value
Noise classification flag value. (Default = 0)
ATBD section 4.12 step 1
1
auxiliaryInformation
outlier_filter switch
Controls entrance to the outlier filter subroutine. (Default = 1)
ATBD section 4.6
1
auxiliaryInformation
DRAGANN switch
Controls entrance to the DRAGANN subroutine. (Default =1)
ATBD section 4.2
1
auxiliaryInformation
Geosegment process interval length
Geosegment process interval length. This controls the amount read from ATL03 and ATL09 at a time. (Default = 500000).
Operations
1
auxiliaryInformation
Threshold for canopy statistics
Minimum percentage of canopy photons to compute statistics upon. (Default =0.05)
ATBD section 4.14.1 step 1
1
auxiliaryInformation
Long segment size
Long segment size in number of 20 meter segments along ground track. (Default=500)
ATBD section 4.1 step 1
1
auxiliaryInformation
Maximum number of input ATL09s
Maximum number of input ATL09 files. (Default = 200)
Operations
meters
auxiliaryInformation
DEM threshold
Reference DEM limit used to reclassify signal as noise. (default = 120.0)
ATBD section 4.5 step 4
1
auxiliaryInformation
Maximum number of Gaussian peaks to fit in the data set
Maximum number of Gaussian peaks to fit in the data set in DRAGANN. (Default =10)
ATBD section 4.2 step 9
1
auxiliaryInformation
Threshold for land statistics
Minimum number of photons to compute statistics upon. (Default =50)
ATBD section 2 intro paragraph
meters^2
auxiliaryInformation
Square Radius of filter for canopy
Top of canopy refinement square search radius. (Default = 225.0)
ATBD section 4.8 step 6
1
auxiliaryInformation
Step Gaussian Amplitude optimization
Step size for optimizing the amplitude variable of Gaussian function. (Default = 1.0)
ATBD section 4.2 step 7
meters
auxiliaryInformation
Short Segment Length
Short segment length in meters. (Default = 100.0)
ATBD section 4.13 step 1
1
auxiliaryInformation
Exponential coefficient for controlling the exponential decay of the filter window size as a function of number of signal photons.
Exponential coefficient of the filter window size as a function. (Default = 21.0E-06)
ATBD section 4.4 step 2
1
auxiliaryInformation
Step size for optimizing the standard deviation parameter of Gaussian function.
Step size for optimizing the standard deviation parameter of Gaussian function. (Default = 0.5)
ATBD section 4.2 step 7
1
auxiliaryInformation
cloud_filter switch
Controls entrance to the cloud_filter subroutine. (Default = 0)
ATBD section 4.1.1
1
auxiliaryInformation
Mode decimal parameter
Number of decimal places to consider in mode computation. (Default =1)
ATBD needed for section 4.13 step 3(h_te_mode)
meters
auxiliaryInformation
Reference finalground limit used to reclassify signal as noise. (default = 150.0)
ATBD section 4.13 step 2
finalground threshold
1
auxiliaryInformation
Dragann Parameter
Parameter for controlling the search radius in nearest neighbor search in DRAGANN. (Default = 20)
ATBD section 4.2 step 1
Constants used in the land_vegetation ATBD
Each group contains the segments for one Ground Track. As ICESat-2 orbits the earth, sequential transmit pulses illuminate six ground tracks on the surface of the earth. The track width is approximately 14m. Each ground track is numbered, according to the laser spot number that generates a given ground track. Ground tracks are numbered from the left to the right in the direction of spacecraft travel as: 1L, 1R in the left-most pair of beams; 2L, 2R for the center pair of beams; and 3L, 3R for the right-most pair of beams.
pce1
strong
gt3r
profile_3
1
Forward
seconds since 2018-01-01
delta time
time
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.
ATL03
1
referenceInformation
indicies of classed photons
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.
Retained from prior a_alt_science_ph packet
delta_time
1
photon land atbd classification
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.
Land ATBD section 4.10
delta_time
noise ground canopy top_of_canopy
0
1
2
3
1
dragann flag
Flag indicating the labeling of DRAGANN noise filtering for a given photon.
Land ATBD section 2.3.5
delta_time
noise signal
0
1
1
referenceInformation
segment id of photon
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.
Retained from prior a_alt_science_ph packet
delta_time
Contains parameters related to individual photons.
Data are stored at the signal-photon classification rate.
degrees
latitude
latitude
Latitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time longitude
-90.
90.
seconds since 2018-01-01
mean_pass_time
time
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.
Land ATBD section 2.4
latitude longitude
1
referenceInformation
reference ground track
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.
Operations
delta_time latitude longitude
1
1387
127
1
referenceInformation
dem source flag
Indicates source of the DEM height. Values: 0=None, 1=Arctic, 2=GMTED, 3=MSS, 4=Antarctic.
Atmosphere ATBD
delta_time latitude longitude
none arctic gmted mss antarctic
0
1
2
3
4
0
4
127
1
multiple scattering warning flag
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.
ATL09
delta_time latitude longitude
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
-1
0
1
2
3
4
5
127
1
cloud flag atm
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.
ATL09
delta_time latitude longitude
0
10
3.402823466e+38
1
signal to noise ratio
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.
ATBD section 2.5.14
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas y
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.
ATL03
delta_time latitude longitude
modelResult
consolidated cloud flag
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.
ATL09
delta_time latitude longitude
likely_clear likely_cloudy
0
1
127
1
segment snowcover
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.
ATBD section 4.2.16
delta_time latitude longitude
ice_free_water snow_free_land snow ice
0
1
2
3
0
3
3.402823466e+38
radians
referenceInformation
beam azimuth
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.
ATL03
delta_time latitude longitude
degrees_east
referenceInformation
solar azimuth
The direction, eastwards from north, of the sun vector as seen by an observer at the laser ground spot.
ATL03g ATBD
delta_time latitude longitude
1
referenceInformation
point spread function flag
Flag is set to 1 if the point spread function (computed as sigma_atlas_land) has exceeded the threshold (1 m)
Land/Veg ATBD
delta_time latitude longitude
below_threshold above_threshold
0
1
0
1
degrees
longitude
longitude
Longitude of the center-most signal photon within each segment.
Land ATBD section 2.4
delta_time latitude
-180.
180.
255
1
segment watermask
Water mask(i.e. flag) indicating inland water as referenced from the Global Raster Water Mask(ANC33) at 250 m spatial resolution.
ATBD section 2.4.15
delta_time latitude longitude
no_water water
0
1
0
1
1
referenceInformation
end geolocation segment bin
Geolocation segment number of the last photon in the land segment.
ATL03
delta_time latitude longitude
1
referenceInformation
surface type
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.
ATL03 ATBD, Section 4
delta_time latitude longitude
not_type is_type
0
1
0
1
127
1
brightness flag
Flag indicating that the ground surface is bright (e.g. snow-covered or other bright surfaces)
Land ATBD section 2.4.21
delta_time latitude longitude
not_bright_surface bright_surface
0
1
255
1
segment landcover
IGBP Land Cover Surface type classification as reference from MODIS Land Cover(ANC18) at the 0.5 arcsecond resolution.
ATBD section 2.4.14
delta_time latitude longitude
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
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
0
16
1
ph removal flag
Flag indicating more than ph_removal_percent_limit (default 50.0) removed from land segment due to failing QA tests
ATBD section 4.13
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
1
apparent surface reflectance
Apparent surface reflectance
ATL09
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas land
Total vertical geolocation error due to ranging and local surface slope. The parameter is computed for ATL08 as described in equation 1.2.
Land ATBD section 2.5.13
delta_time latitude longitude
1
referenceInformation
begin geolocation segment bin
Geolocation segment number of the first photon in the land segment.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas x
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.
ATL03
delta_time latitude longitude
3.402823466e+38
meters
referenceInformation
dem height
Best available DEM (in priority of Arctic/Antarctic/GMTED/MSS) value at the geolocation point. Height is in meters above the WGS84 Ellipsoid.
GIMP, GMTED,MSS
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
beam co-elevation
Co-elevation (CE) is direction from vertical of the laser beam as seen by an observer located at the laser ground spot.
ATL03
delta_time latitude longitude
3.402823466e+38
1
referenceInformation
sigma atlas topo
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.
Land ATBD section 2.5.12
delta_time latitude longitude
2147483647
1
night flag
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.
Land ATBD section 2.4.8
delta_time latitude longitude
day night
0
1
seconds since 2018-01-01
referenceInformation
delta time begin
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
referenceInformation
height uncertainty
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.
ATL03
delta_time latitude longitude
3.402823466e+38
1
kilometers
last segment extended
last_seg_extend
The distance (km) that the last ATL08 processing segment in a file is either extended or overlapped with the previous ATL08 processing segment.
Land ATBD 13March2019, Section 2.4.20
delta_time latitude longitude
3.402823466e+38
radians
referenceInformation
atlas pointing angle
Off nadir pointing angle (in radians) of the satellite to increase spatial sampling in the non-polar regions. ATLAS_PA =90degs-beam_coelev.
ATL03
delta_time latitude longitude
1
photon index begin
Index (1-based) within the photon-rate data (/land_segments/photons) of the first photon within this each land segment.
Derived
delta_time latitude longitude
degrees
referenceInformation
solar elevation
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.
ATL03g ATBD
delta_time latitude longitude
seconds since 2018-01-01
referenceInformation
delta time end
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.
Derived (gps_seconds-gps_sec_offset)
delta_time latitude longitude
127
modelResult
cloud folding flag
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.
ATL09
delta_time latitude longitude
no_folding goes5_indicates profile_indicates both_indicate
0
1
2
3
0
3
1
number of photons
Number of photons within each land segment.
Derived
delta_time latitude longitude
2147483647
1
terrain flag
Terrain flag quality check to indicate a deviation above a threshold from the reference DEM height reported on the product.
Land ATBD section 2.4.8
delta_time latitude longitude
below_threshold above_threshold
0
1
2147483647
1
segment urban flag
The urban flag indicates that a segment is likely located over an urban area.
Land ATBD section 2.4.17
delta_time latitude longitude
not_urban urban
0
1
1
dem removal flag
Flag indicating more than dem_removal_percent_limit (default 20.0) removed from land segment due to failing DEM-QA tests
ATBD section 2.4.11
delta_time latitude longitude
below_threshold above_threshold
0
1
3.402823466e+38
meters
h dif from reference
Difference between h_te_median and ref_DEM
Land ATBD section 2.4
delta_time latitude longitude
Contains data categorized as land at 100 meter intervals.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
height canopy
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
1
modelResult
canopy relative height confidence
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).
Land/Veg ATBD 13March2019, Section 2.2.21
../delta_time ../latitude ../longitude
<5%_canopy >=5%_canopy_<5%_ground >=5%_canopy_>=5%_ground
0
1
2
0
2
3.402823466e+38
meters
absolute segment median canopy height
The median of individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.6
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum canopy height
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.
Land ATBD section 2.2.10
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute mean canopy height
Mean of the individual absolute canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.4
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median canopy height
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.
Land ATBD section 2.2.8
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute segment canopy height
The 98% height of all the absolute individual canopy heights referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.2
../delta_time ../latitude ../longitude
3.402823466e+38
meters
top of canopy roughness
Standard deviation of the relative heights of all photons classified as top of canopy within the segment
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
absolute minimum canopy height
The minimum of absolute individual canopy heights within segment referenced above the WGS84 Ellipsoid.
Land ATBD section 2.2.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy diff to median height
Difference between h_canopy and h_median_canopy
Land ATBD section 4.12
../delta_time ../latitude ../longitude
canopy quadratic mean
The quadratic mean height of individual classified relative canopy photon heights above the estimated terrain surface.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
1
number canopy photons
The number of photons classified as canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
centroid height
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
canopy absolute height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
landsat percentage canopy
Average percentage value of the valid (value <= 100) Landsat Tree Cover Continuous Fields product for each 100 m segment
Land ATBD section 2.2.24
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean canopy height
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.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
canopy height metrics
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%.
Land ATBD section 2.2.3
../delta_time ../latitude ../longitude
1
number top of canopy photons
The number of photons classified as top of canopy within the segment.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
2147483647
1
canopy flag
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.
Land ATBD section 2.2.22
../delta_time ../latitude ../longitude
no_canopy_present canopy_present
0
1
2147483647
1
landsat flag
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.
Land ATBD section 2.2.25
../delta_time ../latitude ../longitude
canopy_not_assumed_present canopy_assumed_present
0
1
3.402823466e+38
meters
absolute maximum canopy height
Maximum of individual absolute canopy heights within segment referenced above the WGS84 ellipsoid.
Land ATBD section 2.2.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment canopy height uncertainty
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
Land ATBD section 1.5
../delta_time ../latitude ../longitude
3.402823466e+38
1
canopy openness
Standard Deviation of all photons classified as canopy photons within the segment to provide inference of canopy openness.
Land ATBD section 4.12
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum canopy height
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.
Land ATBD section 2.2.12
../delta_time ../latitude ../longitude
Contains height parameters based on the land algorithm.
Data are stored as aggregates of 100 meters.
3.402823466e+38
meters
uncertainty of h_te_mean
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
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mean terrain height
The mean of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
minimum terrain height
The minimum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
interpolated terrain surface height
Interpolated terrain surface height above the WGS84 Ellipsoid at the midpoint of the segment.
Land ATBD section 4.9
../delta_time ../latitude ../longitude
3.402823466e+38
meters
maximum terrain height
The maximum of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
skew of terrain heights
The skewness of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
median terrain height
The median of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
segment terrain height best fit
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.
Land ATBD section 2.1.15
../delta_time ../latitude ../longitude
segment terrain roughness
The standard deviation of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
3.402823466e+38
1
segment terrain slope
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.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
1
number of ground photons
The number of the photons classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
3.402823466e+38
meters
mode of terrain heights
The mode of the photon heights above the WGS84 Ellipsoid, classified as terrain within the segment.
Land ATBD section 4.11
../delta_time ../latitude ../longitude
Contains terrain parameters at a 100m aggregation.
Data are stored as aggregates of 100 meters.