Sea-level change in the Southeast Asia seas: from satellite observations to numerical modeling

Sea-level trends and variabilities in the Southeast Asia are one of the most complex on the Earth where oceanographic, atmospheric, and climatic phenomena are interplaying at all scales, from global to local and from decadal changes to hourly variability. We took advantage of the 27.5 years of Archiving, Validation, and Interpretation of Satellite Oceanographic data (1993–2020), corrected for major coupled ocean-atmosphere phenomena including El Niño–Southern Oscillation and Pacific Decadal Oscillations, to reveal regional spatial fingerprints of sea-level seasonal variability and the rising trend. Identified regional sea-level dynamic phenomena were further examined using a high-resolution finite element model fitted on 15-arc second topography and driven by astronomic tides, coupled with climatological atmospheric wind and pressure fields. The study substantiated that the seasonal sea-level dynamics in the South China Sea is modulated mainly by winds, while the magnitude of sea-level anomalies in the Gulf of Thailand during the northeast monsoon is due to a nonlinear interaction between the astronomic tide and the wind shear forcing. Our work highlights the importance of satellite altimetry observations in the analysis and understanding of sea-level variability in the Southeast Asia seas.