The data set provides surface water storage (SWS) and groundwater storage (GWS) data for the Northern East African Rift region.
SWS is estimated from a combination of lake water levels observed with satellite altimetry and water surface area derived from the water occurrence maps. The truncated pyramid formula estimates water volume change from these two data sets. The volume change is then converted to surface water storage and uniformly distributed over the lake surface, leading to SWS. To match the spatial resolution of SWS with the spatial resolution of terrestrial water storage (TWS), the resulting maps are spatially Gaussian filtered, half-width 250km.
TWS, as observed with the GRACE and GRACE-FO satellite mission, monitors the sum of changes in the water storage compartments SWS, GWS, snow and ice, and root-zone soil moisture (RZSM). Thus, to estimate GWS for this data set, the water storage compartments are subtracted from TWS. Here, we neglect snow and ice.
The temporal coverage of the data is from April 2020 to May 2023.