• NSIDC DAAC is currently upgrading our data ingest process for NASA Earthdata Cloud. During this transition, users may notice temporary interruptions in data availability or notice small data gaps. All gaps will be resolved as quickly as possible. During this upgrade jpeg browse imagery will also not be available for preview in Earthdata search. Please reach out to NSIDC User Services with any questions or concerns.

  • The NSIDC DAAC is retiring access to its legacy, on-premises data archive and transitioning to the NASA Earthdata Cloud as the primary data archive. View planned retirement dates here.

ATLAS/ICESat-2 L3A Calibrated Backscatter Profiles and Atmospheric Layer Characteristics, Version 2
Data set id:
ATL09
DOI: 10.5067/ATLAS/ATL09.002
There is a more recent version of these data.
Version Summary
Changes for this version include:

  • Replaced the binary cloud_flag_asr parameter with cloud_conf_flag_asr (0-5) in the routine that computes layer_flag. This new parameter combines apparent surface reflectance (ASR) cloud detection and Density Dimension Algorithm (DDA) cloud detection into a single, consolidated confidence flag.

  • Corrected several issues related to units in the ATL09 documentation and product template.

  • Added a layer_conf_dens parameter which indicates the confidence associated with the corresponding layer detection.

  • Added constants phi_land and phi_ocean as adjustable (input) parameters in the algorithm that determines whether a cloud is present based on the measured ASR.

  • Modified the start bin in the blowing snow optical depth algorithm to mitigate a problem in v01 which led to unrealistically high values of optical depth.

  • Fixed a bug in the surf_ht_dens_mod algorithm.

  • Changed the nighttime QUANTILE1 to 0.97.

  • Corrected an issue where an invalid density value could contaminate the computed value.

  • Updated a hard-coded cloud thickness and separation value in v01 to allow the control file overrides to work correctly.

  • Changed the default value for layer_conf to be invalid.

  • Modified the surface height removal implemented in v01 to handle clouds at surfaces more than 300 m thick.

  • Added blowing snow = invalid to the multiple scattering warning flag (msw_flag) criteria for msw_flag = 0. This change addresses logic in the MSW flag that did not treat blowing snow as a layer.

  • Added a 700-bin relative humidity profile to the product (input from ATL04) to better discriminate between clouds and aerosols.

  • Modified the confidence limits for bs_conf in the blowing snow algorithm.

In this section
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Overview

This data set (ATL09) contains calibrated, attenuated backscatter profiles, layer integrated attenuated backscatter, and other parameters including cloud layer height and atmospheric characteristics obtained from the data. 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):
CLOUD PROPERTIES
LIDAR BACKSCATTER
Platform(s):
ICESat-2
Sensor(s):
ATLAS
Data Format(s):
HDF5
Temporal Coverage:
  • 13 October 2018 to 15 November 2019
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.

Data Access & Tools

This data set has been retired. There is a more recent version of these data.

Documentation

Help Articles

General Questions & FAQs

What subsetting and reformatting services are available for ICESat-2 data?
This short article describes the customization services available for ICESat-2 data using Earthdata Search.
Read More
When will the legacy, on-premises archive be retired?
The NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) is migrating its primary data access from its legacy, on-premises archive to the NASA Earthdata Cloud.
Read More

How to Articles

Filter and order from a data set web page using the Data Access Tool
Many NSIDC DAAC data sets can be accessed using 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:
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Harmony API Quickstart Guide: Customizing NASA NSIDC DAAC data in Earthdata Cloud
This quickstart guide will walk you through the essential steps to start using the Harmony API to request subsetted files with specific spatial and temporal filters applied for select data sets.
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How do I convert an HDF5/HDF-EOS5 file into binary format?
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.
Read More
NASA Earthdata Cloud Data Access Guide
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.
Read More
Search, order, and customize NSIDC DAAC data with NASA Earthdata Search
This article highlights the NSIDC DAAC data sets available with customization options and outlines a workflow for searching, ordering, and customizing data in NASA Earthdata Search. This approach is ideal for users who want to download data to their local machine.
Read More