G-REALM: Investigating datum translations for integration of altimeter-derived operational water level products with in situ lake and reservoir gauge data.
Event: 2015 Ocean Surface Topography Science Team Meeting
Session: Others (poster only)
Presentation type: Type Poster
Contribution: PDF file
G-REALM is a NASA/USDA funded operational program offering water-level products for lakes and reservoirs as derived from the NASA/CNES and ESA/ISRO/CNES radar altimeter missions. The main stakeholder is the USDA/FAS though many other end-users utilize the products for a variety of interdisciplinary science and operational programs. While USDA analysts require relative lake level variations, there is a demand for products based on orthometric datums to more easily integrate the altimeter results into time series of archival (and often sporadic) gauge-based measurements. 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 also introduces datum translation factors that enable the satellite measurements to be converted to WGS84 and various Geoid reference frames. Here, we discuss both the upgrade and the translation factors, assessing their accuracy via comparison with in situ data from around the world.