• On Wednesday, May 29 from 9:00 a.m. to 11:00 a.m. (US Mountain Time), the following data collections may not be available due to a planned system maintenance: ASO, AMSR Unified, AMSR-E, Aquarius, High Mountain Asia, IceBridge, ICESat/GLAS, ICESat-2, LVIS, MEaSUREs, MODIS, Nimbus, SMAP, SnowEx, SSM/I-SSMIS and VIIRS. Users of the SMAP near real-time products should use the Persistent HTTPS File System for data access. 

  • For a list of known issues with this product, see the Known Issues document under the Documentation section of the page.

ATLAS/ICESat-2 L3A Land Ice Height, Version 6
Data set id:
ATL06
DOI: 10.5067/ATLAS/ATL06.006
This is the most recent version of these data.
Version Summary
Changes for Version 6 include:

  • Processing data for all global land regions. These data are considered experimental, and no quality checks are being performed for the data outside of the polar regions.

  • Dynamically computing the radial component of geolocation uncertainty (sigma_geo_r). Previously, this value was fixed. The uncertainty is calculated for ATL03 (sigma_h) and the value is passed through to ATL06 (sigma_geo_r). Values for the horizontal geolocation uncertainties (sigma_geo_at and sigma_geo_xt) remain at fixed, pessimistic values of 5 m.

Overview

This data set (ATL06) provides geolocated, land-ice surface heights (above the WGS 84 ellipsoid, ITRF2014 reference frame), plus ancillary parameters that can be used to interpret and assess the quality of the height estimates. The data were acquired by the Advanced Topographic Laser Altimeter System (ATLAS) instrument on board the Ice, Cloud and land Elevation Satellite-2 (ICESat-2) observatory.
Parameter(s):
GLACIER ELEVATION/ICE SHEET ELEVATION
Platform(s):
ICESat-2
Sensor(s):
ATLAS
Data Format(s):
HDF5
Temporal Coverage:
14 October 2018 to present
Temporal Resolution:
  • 91 day
Spatial Resolution:
  • Not Specified
Spatial Reference System(s):
WGS 84
EPSG:4326
Spatial Coverage:
N:
90
S:
-90
E:
180
W:
-180
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.
Strengths and Limitations

Strengths

  • This data set is suitable for assessing the change of land ice height (especially ice sheets) (Shen et al., 2020) at a seasonal scale or longer because the ICESat-2 satellite has a repeat cycle of 91 days and the file names contain convenient spatio-temporal information (cycle number and ground track).
  • This data set provides geolocated land ice surface heights with centimeter-scale precision and several-meter horizontal positioning accuracy (Brunt et al., 2020) along 40 m segments of ground track, spaced 20 m apart (Smith et al., 2019). Brunt et al. (2020) assessed the accuracy of ATL06 mostly over relatively flat terrain (i.e., ice sheets) and have concluded that it is more accurate and precise than any prior altimetric product.
  • Measurement bias has been well-characterized, and strategies used to mitigate biases are outlined in the User Guide (ATL06 User Guide; ATL06 ATBD). Corrections to account for these biases are either applied to surface height or are included as an accompanying field, contributing to ATL06’s improved accuracy and precision over ATL03 (Smith et al., 2020).

Limitations

  • For the assessment of land ice mass change, height measurements provided by this product must be corrected for changes in the density of the firn (firn air content) and corrections for solid earth vertical motion through time. Estimates of firn air content are currently associated with large uncertainties (Smith et al., 2020).
  • The accuracy of these data is not regionally consistent and depends on local surface conditions and terrain (Shen et al., 2020). Data assessments report that errors increase with increasing surface roughness and slope (Brunt et al., 2020; Shen et al., 2020), so height information is less accurate in areas with high surface roughness and complex terrain features (i.e., slopes greater than 20 degrees or in proximity to a high degree of crevassing).  
  • The ATL06 product is not corrected for the atmospheric and subsurface scattering that delays photon travel-time, resulting in negatively biased surface measurements (ATL06 ATBD, ATL06 User Guide). Studies have reported a small systematic low bias (Shen et al., 2020) and noted that the loss of accuracy due to atmospheric scattering is affected most significantly when cloud optical thickness exceeds a value of 2 (in the case of smooth surfaces) (Smith et al., 2019).
  • ATL06 is derived from the ATL03 product, which does not always correctly identify signal ground-return photon events. In some cases, clusters of misidentified photons can result in relatively larger errors (ATL06 User Guide).
  • Since ATL06 reports elevations in 40 m overlapping segments, it cannot resolve features such as cracks and rifts that are smaller than this (Herzfeld et al., 2020).
  • In rough or steeply sloping areas of the ice sheet, quality of retrieved segments may be low, as indicated by the atl06_quality_summary flag; however, some flagged segments may be of usable quality if they can be reliably identified with another method.
     

Data Access & Tools

A free NASA Earthdata Login account is required to access these data. Learn More

Help Articles

General Questions & FAQs

This article covers frequently asked questions about the NASA NSIDC DAAC's Earthdata cloud migration project and what it means to data users.
This short article describes the customization services available for ICESat-2 data using Earthdata Search.

How to Articles

Many NSIDC DAAC data sets can be accessed using the NSIDC DAAC's Data Access Tool. This tool provides the ability to search and filter data with spatial and temporal constraints using a map-based interface.Users have the option to
To convert HDF5 files into binary format you will need to use the h5dump utility, which is part of the HDF5 distribution available from the HDF Group. How you install HDF5 depends on your operating system.
Learn the basic steps for using OpenAltimetry to browse and download ICESat-2 data products.
This guide will provide an overview of the altimetry measurements and data sets across the missions, as well as a guide for accessing the data through NASA Earthdata Search and programmatically using an Application Programming Interface (API).
The NASA Earthdata Cloud is the NASA cloud-based archive of Earth observations. It is hosted by Amazon Web Services (AWS). Learn how to find and access NSIDC DAAC data directly in the cloud.
All data from the NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) can be accessed directly from our HTTPS file system, using wget or curl. Basic command line instructions are provided in the article below. 
NASA Earthdata Search is a map-based interface where a user can search for Earth science data, filter results based on spatial and temporal constraints, and order data with customizations including re-formatting, re-projecting, and spatial and parameter subsetting.
This webinar introduces the ICESat-2 mission and shows you how to explore, access and customize ICESat-2 data with the OpenAltimetry application, using NSIDC DAAC tools, and shows you how to subset, reformat and analyze the data using Python.