HydroSat: geometric quantities of the global water cycle from geodetic satellites

Abstract. Against the backdrop of global change, in terms both climate and demography, there is a pressing need for monitoring water cycle. The publicly available database very limited its spatial temporal coverage worldwide. Moreover, acquisition situ data their delivery to have been decline since late 1970s, be it economical or political reasons. Given insufficient from gauge networks, with no outlook improvement, spaceborne approaches under investigation some years now. Satellite-based Earth observation homogeneous accuracy has demonstrated potential alternative measurements. This paper presents HydroSat as containing geometric quantities cycle geodetic satellites. provides time series uncertainty level satellite altimetry, surface extent imagery, terrestrial storage anomaly represented equivalent height gravimetry, lake reservoir volume combination altimetry river discharge either imagery. these datasets varies depends on availability These products, which are complementary existing can contribute our understanding within system several ways. They incorporated hydrological modeling, they current future observations, define indicators past state freshwater system. through http://hydrosat.gis.uni-stuttgart.de (last access: 18 May 2022???????). snapshot all (taken April 2021) GFZ Data Services at https://doi.org/10.5880/fidgeo.2021.017 (Tourian et al., 2021).