Refinement of Mean Dynamic Topography Over Island Areas Using Airborne Gravimetry and Satellite Altimetry Data in the Northwestern South China Sea

The determination of high-quality mean dynamic topography (MDT) over island areas faces multiple challenges, due to the error in a global geopotential model (GGM) as well contaminated waveforms satellite altimetry data and scarcity surveyed gravimetric observations. We study potential enhance regional quasi-geoid/MDT by using recently released altimetric gravity airborne Numerical experiments Paracel Islands northwestern South China Sea show that combination enhances local field, reduces errors associated quasi-geoid, comparison result directly derived from GGM. results demonstrate direct application GGM may cause significant oscillations MDT areas, magnitude exceeding 6 cm. incorporation slightly these errors; however, bubble-like are prominent, suggesting alone be insufficient for high-accuracy recovery. In contrast, combining dramatically oscillations, several centimeters, indicating surveys necessary with centimeter-level accuracy coastal/island areas. Further independent ocean shows geostrophic velocities computed merging high-degree can reconstruct real surface circulation; GOCE-based (Gravity Field Steady-State Ocean Circulation Explorer) GGMs preferable reference models determination.