Kate OBrien (ESSIC/University of Maryland, USA); Brian Beckley (SGT, USA); Xu Yang (SGT, USA); Charon Birkett (University of Maryland, USA)

G-REALM is a NASA/USDA funded operational program offering water-level products for lakes and reservoirs that are currently derived from the NASA/CNES Topex/Jason series of radar altimeters. The main stakeholder is the USDA/Foreign Agricultural Service though many other end-users utilize the products for a variety of interdisciplinary science and operational programs. There is increasing demand for a more global monitoring service that in particular, captures the variations in the smallest (1 to 100km2) reservoirs and water holdings in arid and semi-arid regions. Here, water resources are critical to both agriculture and regional security. A recent G-REALM 10-day resolution product upgrade and expansion has allowed for more accurate lake level products and for a greater number of water bodies. The upgrade has also introduced datum translation factors that enable the satellite measurements to be converted to orthometric reference frames. Current G-REALM tasks focus on i) SARAL product creation with a view to potential mergers with Sentinel-3 products, ii) Jason-3 validation exercises, particularly investigating the performance of the upgraded DIODE/DEM mode, and iii) Sentinel-3 SAR data exploration and application.