The dataset provides a set of 8 land ocean masks as NetCDF files based on the maps provided by the datasets ESA CCI Water Bodies - v4.0, Ocean-Map-150m-P13Y-2000-v4.0. The masks come as regular lon/lat grids in 0.1°, 0.25°, 0.5° and 1° spatial resolution, each as a version with and without Greenland and the antarctic regions (anything south of 60° S).
The data fields of the individual datasets comprise of
a) a field with information on the fraction of land in a grid cell, defined by the number of 150m cells of the source dataset lying within a target grid cell,
b) a field with a flag (1 or 0) if a a grid cell contains more than 50% land area or not, and
c) a field with a flag (1 or 0) if a grid cell contains any land at all.
The dataset was generated in the course of the project "Global Gravity-based Groundwater Product (G3P)" to facilitate data production on a regular grid and to mask out oceans. G3P was funded by the EU Horizon 2020 programme in response to the call LC-SPACE-04-EO-2019-2020 “Copernicus evolution – Research activities in support of cross-cutting applications between Copernicus services” under grant agreement No. 870353.
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.