BARYSTATIC sea level changes are due to freshwater exchanges with the continents, including ice mass changes from Greenland, Antarctica and continental glaciers, as well as freshwater fluxes from continental areas (i.e. large river basins such as the Amazon or Mississippi).

MANOMETRIC sea level changes are due to several processes, including the atmosphere - ocean circulation, sea level fingerprints or global water cycle. Climate modes, such as the El Nino Southern Oscillation, Arctic Oscillation, North Atlantic Oscillation or Southern Annular Mode, have also been shown to significantly influence manometric sea level changes (e.g. Pfeffer et al., 2022).

The GRACE and GRACE Follow-On missions monitor the time-variations in the gravity field almost continuously since 2002. Numerous centers distribute time-lapse solutions of the Earth’s gravitational potential, delivered as Stokes coefficients, known as Level 2 solutions. The Level 2 solutions need to be corrected for several geophysical effects and instrumental errors, converted into surface mass anomalies and projected onto the ellipsoid. The resulting gridded surface mass anomalies with appropriate corrections applied are referred to as Level 3 solutions. Several sources of errors affect the solutions of Level 2 and 3, imposed by the satellite configuration, instrumental errors and uncertainties in the geophysical corrections used to process the measurements. We use the ensemble approach of Blazquez et al., (2018), to robustly estimate the manometric and barystatic sea level changes and their uncertainties.

References:

- Blazquez, A., Meyssignac, B., Lemoine, J.-M., Berthier, E., Ribes, A., Cazenave, A. (2018). Exploring the uncertainty in GRACE estimates of the mass redistributions at the Earth surface: implications for the global water and sea level budgets, Geophysical Journal International, 215 (1), 415–430, https://doi.org/10.1093/gji/ggy293

- Pfeffer, J., Cazenave, A. & Barnoud, A. (2022). Analysis of the interannual variability in satellite gravity solutions: detection of climate modes fingerprints in water mass displacements across continents and oceans. Clim Dyn 58, 1065–1084. https://doi.org/10.1007/s00382-021-05953-z