ICESat-2 Operational Inland Surface Water Products for Global Hydrologic Science

Since October 2018 or over three years, ICESat-2 observations have been producing global, operational data products targeting the hydrology of up to 1.5 million lakes, reservoirs, rivers, estuaries, and nearshore coasts over 0.1 sq km in area or 100m width. The principal products are water height, crossing slope, significant wave height, wind speed, 532 nm subsurface attenuation, and coarse water depth. As of Fall 2021, ICESat-2 Inland Surface Water products have expanded into two suites of products. The first is the original along track, high resolution Inland Surface Water Data that has now been improved and updated through ATL13 Version 5. ATL13 along track products, derived directly from ATL03 georeferenced photons for each of the six ICESat-2 ATLAS 532nm beams, are produced at a continuous short segment rate ranging from ~25-100 m depending on surface signal photon density. A new second product is the Mean Inland Surface Water Data or ATL22 Version 1. ATL22 mean values are computed from the ATL13 along track products for all distinct transects within a given water body. Both ATL13 and ATL22 products are publicly available at the National Snow and Ice Data Center, allowing a user to study at either desired resolution, with each subsequent release reprocessed from October 2018 to present. Results presented herein showcase several examples of the ATL13 and ATL22 data for a representative range of water body types and sizes, as well as its capability for describing global inland surface water states and processes. Results from the first three years of ICESat-2/ATLAS observations demonstrate ATL13s high capability for describing accurate water surface heights and crossing lengths required in river discharge and lake storage modeling. Unique examples include the continuous water surface elevation change across water bodies, the slopes and braids of rivers, the along track depth of clear water bodies, the progression of wave height and wind speed across a large lake, and the characteristic water surface curvature of many mountain lakes.