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Description

ATL12 contains along-track sea surface height (SSH) of the global open ocean relative to the WGS84 ellipsoid. Height averages, distributions, and uncertainties are provided over ocean segments 400 to 7,000 m in length. Heights relative to the EGM2008 geoid and variables such as photon return rate are provided in 10 m along-track bins within each ocean segment. Additionally, 10 m bins corresponding to ATL07 bright leads are identified, and heights within the bins are averaged over ocean segments to yield accurate SSHs where ice concentrations are greater than 15%. The data were acquired by the Advanced Topographic Laser Altimeter System (ATLAS) instrument on board the ICESat-2 observatory.

Version Description

-Significantly improved ocean surface height in ice-covered water by using aligned ATL07 sea ice reference surface data (leads) if ATL12-estimated heights are considered contaminated by ice
-Added ice-free height estimates based on aligned ATL07 sea ice product reference surface data (leads) at both the ocean segment rate and 10-meter rate
-Added 10-meter rate standard deviation of htybin (htybin_std_seg).
-Added the along-track distance from the equator crossing to the first 10 m bin for each ocean segment (xbind_first_dist_x). This allows accurate alignment for ATL13 short segments with other ICESat-2 data products.
-Added the first photon bias correction for each 10 m along-track bin in each ocean segment (fpb_10m)
-Added the estimated error in first photon bias correction (fpb_corr_stdev)
-Added computation of the sea slope bias estimated from the correlation of photon return rate with along-track 10-meter bin averaged surface height (bin_slopebias)
-Added computation of the sea slope magnitude bias estimated from the covariance of the photon rate and the slope (bin_magslopebias)
-Excluded photons without a valid tide_ocean from ocean segment processing
-Added selective use of ocean scan calibration data to be included or excluded from being processed
-Added usage of ATL03 photon quality into ocean photons selection to remove fully saturated pulses
-Changed the source for bathymetry to the 2022 GEBCO bathymetry grid
-Changed the source for ice concentration (ice_conc) to the high-resolution AMSR2 passive microwave SIC dataset

Product Summary

Platforms
ICESat-2
Instruments
ATLAS
Spatial Extent

N: 88 S: -88 E: 180 W: -180

Geographic Region
GLOBAL OCEAN
Coordinate System
CARTESIAN
Granule Spatial Representation
GEODETIC
Temporal Extent
2018-10-13 to Present
Concept ID
C3566214012-NSIDC_CPRD
Data State
ACTIVE
Number of Files/Granules
9380
Processing Level
3
Published
Science Keywords
Sea Surface Height

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

Morison, J., Hancock, D., Dickinson, S., Robbins, J., Roberts, L., Kwok, R., Palm, S., Smith, B., Jasinski, M., & the ICESat-2 Science Team. (2025). ATLAS/ICESat-2 L3A Ocean Surface Height, Version 7 [Data set]. NASA National Snow and Ice Data Center Distributed Active Archive Center. https://doi.org/10.5067/ATLAS/ATL12.007 Date Accessed: 2026-01-10

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