,,,,- Department of Applied Mathematics and Aerospace Engineering, University of Alicante, 03690 Alicante, Spain (vigo@ua.es)
Ocean angular momentum (OAM) is a key geophysical quantity linking ocean dynamics with Earth rotation, as it constitutes a major excitation mechanism of polar motion and length-of-day variations. OAM variability reflects changes in both the mass distribution of the ocean and the velocity field of ocean currents. Although several operational products provide OAM estimates, most of them rely heavily on numerical ocean circulation models, which may introduce model-dependent uncertainties.
Geostrophic currents (GC), which arise from the balance between the Coriolis force and the horizontal pressure gradient, dominate large-scale ocean circulation and therefore play a central role in OAM variability. Recent advances in satellite geodesy now enable the estimation of GC from observations that are largely independent of dynamical ocean models. In particular, GC can be derived by combining Sea Surface Height from satellite altimetry, an independent geoid obtained from satellite gravity missions, and temperature and salinity profiles, allowing the reconstruction of global geostrophic velocity fields at different depths.
In this study, these satellite-based GC fields, with a spatial resolution of 0.25° × 0.25°, are used to compute OAM and its temporal variability. The resulting OAM series are compared with several existing OAM products commonly used in Earth rotation studies. The proposed approach is expected to provide more robust and geophysically consistent OAM estimates, since the satellite-derived GC show improved agreement with in situ current observations compared to model-based products. This work therefore strengthens the connection between satellite gravimetry, ocean dynamics, and Earth rotation research.
Acknowledgements: This work was primarily supported by the Spanish national project PID2021-122142OB-I00 (MCIN/AEI/10.13039/501100011033), and additionally by the EU Horizon Europe project SEA4FUTURE (Grant Agreement No. 101212647).
How to cite: Vigo, M. I., Vargas-Alemañy, J. A., García-García, D., Ferrándiz, J. M., and Wang, M.: Satellite-Based Geostrophic Currents for Improved Ocean Angular Momentum Estimates , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23230, https://doi.org/10.5194/egusphere-egu26-23230, 2026.
