Total Ocean Mass Estimates from GFZ RL06 of GRACE and GRACE-FO: Mitigating Effects of Coastal Leakage

Temporal variations in the total ocean mass representing the barystatic part of present-day global-mean sea-level rise can be unambigously inferred from time-series of global gravity fields as provided by the GRACE and GRACE-FO missions. A spatial integration over all ocean regions, however, largely underestimates present-day rates as long as the effects of spatial leakage along the coasts of in particular Antarctica, Greenland, and the various islands of the Canadian Archipelago are not properly considered.

Based on the recent release 06 of monthly gravity fields processed at GFZ, we quantify (and subsequently correct) the contribution of spatial leakage to the post-processed mass anomalies of continental water storage and ocean bottom pressure. We find that by utilizing the sea level equation to predict spatially variable ocean mass trends out of the (leakage-corrected) terrrestial mass distributions from GRACE and GRACE-FO consistent results are obtained also from spatial integrations over ocean masks with different coastal buffer zones ranging from 200 to 600 km. The results will be made available to the public with the next update of the GFZ Level-3 mass anomaly products via gravis.gfz-potsdam.de.