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.

How to cite: Boergens, E.: From Observations of the Earth’s Gravity Field to Insights into Hydrology, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-3354, https://doi.org/10.5194/egusphere-egu26-3354, 2026.

EGU26-3354

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Since the time of Kepler, Newton, and Huygens in the 17th century, geodesy has been concerned with determining the Earth’s figure, orientation, and gravitational field. The dawn of the space age in 1957 gave rise to a new branch of the discipline: satellite geodesy. It was only through the use of satellites that geodesy truly became a global science - oceans ceased to be barriers, and the Earth could be observed and measured as an integrated whole using consistent datasets. Particular attention was devoted to resolving the spatial structure of the Earth’s gravity field and, eventually, its temporal variations. Knowledge of the gravity field forms a natural link to the study of the Earth’s interior, the circulation of the oceans, and, more recently, the climate system. Today, changes in the gravity field provide key insights into climate change, including ice mass loss in Greenland and Antarctica, sea-level rise, and broader changes in the global water cycle. These advances have only been possible through the use of highly sophisticated gravity-field satellites, a field known as satellite gravimetry.

During the first four decades of space exploration, satellite gravimetry relied primarily on analyzing the orbital motion of satellites. Due to the uneven global distribution of tracking stations, initially limited measurement accuracy, and shortcomings in early analysis models, reconstructing global models of the Earth’s gravity field posed a major challenge. A decisive breakthrough came in the final decade of the 20th century with the transition from passive satellites to missions equipped with dedicated, high-precision instrumentation for gravity-field determination. The Vening Meinesz lecture will review the historical background of satellite gravimetry as well as mission objectives, measurement principles and implementation challenges of modern gravity missions like CHAMP, GRACE, GOCE, and GRACE-FO. It will further highlight selected scientific results and applications from these missions and outline opportunities for the next generation of geodesists arising from future gravity field missions currently under development.

Further reading: Frank Flechtner, Christoph Reigber, Reiner Rummel, and Georges Balmino (2021): Satellite Gravimetry: A Review of Its Realization, Surveys in Geophysics, 42:1029–1074, https://doi.org/10.1007/s10712-021-09658-0

How to cite: Flechtner, F.: Satellite Gravimetry: Realization and Further Prospects, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9119, https://doi.org/10.5194/egusphere-egu26-9119, 2026.

EGU26-9119

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