On Wednesday, July 28 from 8:00 a.m. to 4:00 p.m. (USA Mountain Time), the following data collections may not be available due to planned system maintenance: AMSR-E, Aquarius, High Mountain Asia, IceBridge, ICESat/GLAS, ICESat-2, MEaSUREs, MODIS, NISE, SMAP, SnowEx, and VIIRS.
Data Set ID: 

ATLAS/ICESat-2 L3A Ocean Surface Height, Version 2

This data set (ATL12) contains along-track sea surface heights at variable length scales over cloud-free regions. Estimates of height distributions, surface roughness, surface slope, and apparent reflectance are also provided. 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.

There is a more recent version of these data.

Version Summary: 

Changes for this version include:

  • The bckgrd_rate parameter (/gt[x]/ssh_segments/stats/) is now read from ATL03 and the mean value for signal photons is written to ATL12 as /gt[x]/ssh_segments/stats/backgr_seg.
  • The input photon arrays used to estimate sea state bias (x, height, time, ocean-segment, and histogram-bin-index/signal-photon-mask) are now sorted by along-track x.
  • All data with heights greater than the shore depth (default = -10 m) are not processed as ocean to ensure ocean processing doesn't occur over land.
  • Changed the processing code and ATL12 template to allow invalid values for significant wave height (/gt[x]/ssh_segments/heights/swh) and sea state bias (/gtx/ssh_segments/heights/bin_ssbias).
  • Fixed errors that caused segments to be skipped after long gaps and along the boundary between two orbits.
  • Updated parameter name "ds_y_bins" to "ds_y_bincenters" in the ATL12 product to be consistent with the ATBD and developmental code.
  • Changed the ocean histogram bin center height edges to eliminate a 0.5 cm ambiguity in histogram statistics.
  • Corrected the order in which surface types are listed on the surf_type_prcnt parameter description.
  • Added an ocean photon selection, boxcar smoothing parameter (/ancillary_data/ocean/pts2bin) and assigned it a default value of 21. This value can be overridden in the control file.
  • Made code updates to modify which residual histogram bins are selected for use. The code now includes a second-pass threshold test based on histogram far tails.
  • Added a tide_equilibrium_seg parameter in /gt[x]/ssh_segments/stats that is the mean of the ATL03 equilibrium tide values for signal photons.
  • Updated the SNRc calculation to use the same process as the deconvolution noise filtering.
  • Shifted the TEP bin center heights to match the fine histogram bin center heights. This allows for better alignment of the surface histogram after Weiner deconvolution of the impulse response.
Data Format(s):
  • HDF5
Spatial Coverage:
N: 90, 
S: -90, 
E: 180, 
W: -180
Spatial Resolution:
  • Varies
Temporal Coverage:
  • 13 October 2018 to 15 November 2019
Temporal Resolution91 dayMetadata XML:View Metadata Record
Data Contributor(s):James Morison, David Hancock, Suzanne Dickinson, John Robbins, Leeann Roberts, et al

Geographic Coverage

No access options.

As a condition of using these data, you must cite the use of this data set using the following citation. For more information, see our Use and Copyright Web page.

Morison, J. H., D. Hancock, S. Dickinson, J. Robbins, L. Roberts, R. Kwok, S. P. Palm, B. Smith, M. F. Jasinski, and the ICESat-2 Science Team. 2019. ATLAS/ICESat-2 L3A Ocean Surface Height, Version 2. [Indicate subset used]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi: https://doi.org/10.5067/ATLAS/ATL12.002. [Date Accessed].

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