Operational ICESat-2 Inland Surface Water Products for Global Hydrology: Recent Enhancements

ICESat-2 has been routinely observing up to 1.5 million lakes, reservoirs, rivers, estuaries, and nearshore coasts over a period of 4 years, for global water bodies over 0.1 sq km in area or 100m width. The principal products are water height, slope, significant wave height, wind speed, 532 nm subsurface attenuation, and coarse water depth. Two suites of Inland Surface Water products have been computed. The first is the original continuous along track, high resolution Inland Surface Water Data, or ATL13, that has now been improved and updated for height and subsurface attenuation. The most recent version, or ATL13 Ver 6, is derived directly from ATL03 georeferenced photons for each of the six ICESat-2 ATLAS 532nm beams, and are produced at a continuous short segment rate ranging from 25-100 m depending on surface signal photon density. The second product is the Mean Inland Surface Water Data product or ATL22 Ver 3, computed over the same water bodies and crossing times as ATL13. ATL22 and ATL13 products are computed for all distinct transects within a given water body and made publicly available at the National Snow and Ice Data Center. Each subsequent release provides both improvements to earlier versions and are reprocessed from October 2018 to present. Results presented here show representative examples of ATL13 and ATL22 for characterizing various water bodies over a range of water body types and sizes, including lakes with variable depth. Results from the first four years of ICESat-2/ATLAS observations demonstrate ATL13's continued high capability for providing hydraulic, dynamic and other quantities useful for typical hydrology science and water resources applications including stream discharge, water body heights, storage change, and bathymetry.