Interannual Sea Level Changes In China Marginal Sea And Their Response To ENSO

The mean sea level changes in China Marginal Sea were investigated based on the Sea Level Anomalies (SLA) altimeter data provided by CNES. Eight areas are chosen to further reveal the annual change of sea level, the variability and characteristics of sea-level height anomaly in the areas along the Yellow Sea Warm Current and the Alongshore Current are also discussed. There exists obvious annual and interannual cycles of SLA, and spatial differences in amplitude of annual cycle and phase of SLA extremum. In the past 17 years, the rising rates have reached to 0.296 cm/yr,0.204 cm/yr,0.260 cm/yr, respectively, in the three areas of BYS (Bohai and Yellow Sea), YRE (Yangtze River Estuary) and SECS(the Southern East China Sea), indicating a spatial difference. Correlative analysis shows that interannual components of SLA have good but opposite response to SOI and meridional wind stress anomalies, in the northern part and southern part of China Marginal Sea separated by 30°N. It is obvious that sea level variation is closely related to SOI and zonal wind stress anomaly, indicating that sea level in China Marginal Sea is affected by ENSO through wind stress. There is also a good relationship between SOI and the wind field over China Marginal Sea, of which the interannual components are corresponding to ENSO. By using correlative analysis between SLA and wind stress anomalies, it is found that the direction of wind stress most strongly affecting the sea level is 8 degrees east by north,84 degrees and 13 degrees east by south separately, over the three areas of BYS, YRE and SECS. The divergence zone and wind field of China Marginal Sea are dominated by atmospheric circulation, which makes SLA response differently between the northern part and southern part of China Marginal Sea. However, ENSO plays an important role in air circulation; hence ENSO affects wind filed and sea level of China Marginal Sea. To sum up, ENSO and wind stress contribute to the sea level change over China Marginal Sea. In detail, ENSO impacts on wind filed of China Marginal Sea, hence affecting the interannual change of sea level.