From Observations of the Earth’s Gravity Field to Insights into Hydrology

The central pillar of my research are the GRACE and GRACE-FO satellite missions. These missions provide a unique opportunity to observe spatial and temporal variations in the Earth’s gravity field. These variations reflect large-scale mass redistributions, which are dominated by water mass transport across continents, oceans, and ice sheets. Consequently, GRACE and its successor mission, GRACE-FO, enable global monitoring of changes in terrestrial water storage (TWS), integrating all water components from surface water over soil moisture, snow and ice, down to groundwater.

In this talk, I will take you on a journey from global observations of the Earth’s gravity field to physically interpretable data products over land and oceans, and demonstrate how these products can be applied in hydrological research.

Global gravity field solutions are typically delivered as spherical harmonic coefficients, a mathematical representation that is not directly accessible to most users. I will show how we transform this complex information into intuitive, user-friendly gridded datasets, including robust uncertainty estimates, an aspect crucial for many practical applications. I will also highlight the importance of such accessible data products for open science initiatives and public data platforms, including the Copernicus Climate Change Service.

Finally, I will present several case studies illustrating the use of TWS data in hydrology. These include the quantification of the ongoing Central European drought that began in 2018, as well as investigations into the interplay between climate change, natural variability, and human influence in the East African Rift region. I will also demonstrate the added value of combining TWS observations with complementary remote sensing datasets to assess global changes in groundwater storage.