Barystatic and manometric sea level variations based on satellite gravimetry

Barystatic and manometric sea level changes represent the mass component of sea level changes at global and regional scales, respectively. Barystatic and manometric sea level changes are estimated using the satellite gravimetry measurements from the GRACE and GRACE-FO missions.

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 variations (e.g., Pfeffer et al., 2022; https://doi.org/10.1007/s00382-021-05953-z).

Two products are distributed:

• Barystatic sea level changes from satellite gravimetry with uncertainties at 1-sigma: monthly time series,
• Manometric sea level changes from satellite gravimetry with uncertainties at 1-sigma: monthly grids with 1x1 degree.

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; https://doi.org/10.1093/gji/ggy293), to robustly estimate the manometric and barystatic sea level changes and their uncertainties.