Interannual Sea Level Variations in the South China Sea Over 19502009
Abstract
Spatial patterns of interannual sea level variations in the South China Sea (SCS) are investigated by analyzing an EOF-based 2-dimensional past sea level reconstruction from 1950 to 2009 and satellite altimetry data from 1993 to 2009. Long-term tide gauge records from 14 selected stations in this region are also used to assess the quality of reconstructed sea levels and determine the rate of sea level along the coastal area. We found that the rising rate of sea levels derived from merged satellite altimetry data during 19932009 and past sea level reconstruction over 19502009 is about 3.9 +/- 0.6mm/yr and 1.7 +/- 0.1 mm/yr, respectively. For the longer period, this rate is not significantly different from the global mean rate (of 1.8 +/- 0.3mm/yr). The interannual mean sea level of the SCS region appears highly correlated with Nino 4 indices (a proxy of El Nino-Southern Oscillation/ENSO), suggesting that the interannual sea level variations over the SCS region is driven by ENSO events. Interpolation of the reconstructed sea level data for 19502009 at sites where tide gauge records are of poor quality (either short or gapped) show that sea level along the Chinese coastal area is rising faster than the global mean rate of 1.8mm/yr. At some sites, the rate is up to 2.5mm/yr.