Variability of sea surface topography in coastal area (study case: Indonesia)

Abstract

The deviation of the sea surface from the geoid reference surface is known as the Sea Surafce Topography (SST). SST is caused by several physical phenomena such as ocean wave, tides, current and atmospheric pressure loading, and the main application of SST is to determine ocean circulation. To get the SST, we use Sea Surface Height (SSH) and Mean Dynamic Topography (MDT) based on 30 years of sea-level data derived from multi-mission of satellite Altimetry and geoid height (Undulation) from Global Gravitation Model EGM-2008. Indonesia is an archipelagic country in the equatorial region that lies between Indian and Pacific oceans. Its geographical setting will affect variability of Sea Surface Topography (SST) in the Indonesian Sea. The anomaly from SST is one of the oceanic parameters that play a crucial role in the ocean dynamic and its possible hazards. We found that the characteristics differ considerably from one place to another, depending on the bathymetric depth and type of sea. The mean SSH varies from about 40 meters and rises to the east up to a height of 80 meters. Likewise, the MDT value increased from 0.5 meters to the east to a height of 1.2 meters. In closed, narrow and shallow seas, the long time-series of those surfaces are less sensitive to the effects of El Niño and La Niña as well as global sea level rise. On the other hand, global sea level rise significantly affects the characteristic of both surfaces over open and deep seas. We hope by using more spatially dense data from multi-mission satellite altimetry, we can see more detail about the local phenomena that influence SST. By studying the variability of SST from more than one cycle (18.6 years) it is expected that it can be used to understand the dynamics of the coastal area in Indonesia.