Quantifying Sea Level Trend and Variability in South East Asian Seas at Seasonal, Interannual and Decadal Time Scales.

Abstract:

The South East Asian sea region spans the largest archipelago in the global ocean and is comprised of many low lying and densely populated coastal areas. It has a complex bathymetry due to presence of shallow continental shelves. It is also the only tropical inter-oceanic region providing a complex oceanic pathway called the Indonesian through flow connecting two major oceans- Pacific and Indian oceans. Understanding sea level variations, one of the best indicators of climate change, in this region is interesting as it involves understanding the above mentioned complex mechanisms. The oceanographic conditions in this region are also highly influenced by events at several timescales such as monsoons, natural climate modes occurring at seasonal to decadal timescale etc. Considering the complex mechanism and processes occurring at different time scales, in our study, we attempt to quantify regional sea level trend and variability in the South East Asian seas at seasonal, interannual and decadal time scales. We first analyse gridded 0.25 degree resolution satellite altimetry data since 1993 at different time scales to study the spatial and temporal variability of regional sea level and its mechanisms. We also use carefully selected tide gauge records since 1970s to study long term sea level variability. To understand its mechanisms, we further use ocean reanalyses. By doing so, we attempt to quantify the contribution of different sea level components, local and remote forcing etc.