Determination of Long-Term Oceanic Mass Change in a Coherent System

The decade long record of satellite gravity measurements from the Gravity Recovery and Climate Experiment (GRACE) provides a unique means for quantifying long-term oceanic mass change, one of the two main driving forces of the global mean sea level (GMSL) rise. Accurate determination of GRACE-observed oceanic mass change relies on a number of factors, including residual error in GRACE observations, uncertainty in the post-glacial rebound (PGR) model (needed for removing PGR effects on oceanic mass change estimates), and more importantly effective separation of oceanic mass signal from terrestrial water storage (TWS) and ice mass change from polar ice sheets and mountain glaciers in a coherent system. In this presentation, we will use global forward modeling (an improved method based on previous regional forward modeling) to estimate GRACE-observed oceanic long-term oceanic mass change, and compare the results with those from other methods. The global forward modeling estimate has apparently better addressed the leakage effect between ocean and TWS and ice mass signals, and can better close the budget of observed sea level change rate from satellite altimeters (with steric correction).