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

ATLAS/ICESat-2 L2A Normalized Relative Backscatter Profiles, Version 6
Data set id:
DOI: 10.5067/ATLAS/ATL04.006
This is the most recent version of these data.
Version Summary
Changes for Version 6 include:

  • Added and modified alpha correction constants to improve calibration in the South Atlantic Anomaly (SAA) area.

  • Slightly modified the boundaries of the SAA box.


ATL04 contains along-track normalized relative backscatter profiles of the atmosphere. The product includes full 532 nm (14 km) uncalibrated attenuated backscatter profiles at 25 times per second for vertical bins of approximately 30 meters. Calibration coefficient values derived from data within the polar regions are also included. 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.
Data Format(s):
Temporal Coverage:
13 October 2018 to present
Temporal Resolution:
  • 91 day
Spatial Resolution:
  • Not Specified
Spatial Reference System(s):
WGS 84
Spatial Coverage:
Blue outlined yellow areas on the map below indicate the spatial coverage for this data set.
Strengths and Limitations


  • This is an L2A product that contains the normalized relative backscatter (NRB) profiles from the surface to 14 km with 30 m vertical and 280 m horizontal resolutions.
  • From the NRB, the raw signal can be computed by adding the background and dividing by the square of the range from the satellite to the bin.
  • Using the molecular backscatter profiles from the surface to 20 km with a 30 m vertical resolution and the NRB, the system calibration constant can be computed.
  • The product contains 2 and 10 m temperature and wind velocity, as well as vertical profiles of temperature, relative humidity, and pressure.


  • The NRB profiles span a limited height range: from the surface to 14 km altitude.
  • Backscatter (clouds/aerosol) at altitude h, where h > 15 km, is folded down and added to the backscatter present at an altitude of h - 15 km (Palm et al., 2021).
  • The signal between 14 and 15 km is not downlinked.
  • Daytime signal to noise is low due to solar background noise.
  • Because of the limited profile length and folding, daytime background is difficult to compute. This can ultimately affect the ability to accurately calibrate the signal (Palm et al., 2021).

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.
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.