Evaluation of the ICESat-2 Inland Water Data Products for Hydrology and Water Resources

Abstract

Global, high resolution data products targeting the hydrology of lakes, reservoirs, rivers, estuaries, and nearshore continental coasts have been developed as part of the ICESat-2 Inland Water Data Product or ATL13. These operational data products are computed from analysis of georeferenced photon clouds of the water surface and subsurface observed by the ICESat-2 Advanced Topographic Laser Altimeter System (ATLAS), a micropulse, high repetition rate, six-beam, 532 nm Lidar. The current principal ATL13 products are water height, slope, significant wave height, 532 nm subsurface attenuation, and water depth. As of late Spring 2020, three releases of ATL13 products covering mid-October 2018 to present have been made public at the National Snow and Ice Data Center, with Release 4 expected in 2020. Each subsequent release provides both improvements to earlier versions and also new hydrology products, at increasing number and higher resolution water bodies. ATL13 currently reports on water bodies over 0.1 sq km or 25 -100m width, identified through a global water body mask containing over 1.5M shapefiles. ATL13 products are reported for any water body transected at the along track scale of 100 signal photon acquisitions, or approximately 25 to 200 m continuous segments (~100m average), depending on water clarity and atmosphere cloudiness. Results presented herein provide an assessment of the ATL13 algorithm using typical examples of inland water data products over a range of water body types, sizes, and products. Evaluations were conducted against existing in situ and airborne data. Results from the first two years of ICESat-2/ATLAS observations demonstrate ATL13’s high capability for providing hydraulic, dynamic and other quantities useful for typical hydrology and water resources applications including stream discharge, water body heights, storage, and bathymetry.