Study On The Seasonal Variations Of Sea Level Changes In China Marginal Seas

Sea level seasonal variations of East China Sea is estimated using tide gauge data,and AVISO altimeter data. Thermosteric sea level are calculated from seawatertemperature of Ishii (2012). It is suggessted that sea level of east sea of china showsprominent seasonal variability.Two experiments are made by using ROMS to studyeffects of wind stress, and their results are compared with the characters of seasonalvariations. The conclusions are drawn as follows:The sea surface height amomaly is completely opposite between winter andsummer, as well as bwtween spring and autumn. In spring, the positive amololyspread from the south and north to middle, and the negative amololy spread from thesouth and north to the middle. The result of EOF (Empirical orthogonal Functional)show that the first two modes attribute to seasonal mode, and the accumulatingcontribution is51.81%. The next three modes are mainly interannual variation withcumulating contribution of about11%.The thermosteric sea level of ECS is similar to T/P sea level about intraseasonalvariation. The thermosteric sea level is lower than the T/P sea level, and thedistribution is similar. The result of EOF show that the first two modes attribute toseasonal mode, and the accumulating contribution is71.3%. The three mode is relatedto ENSO with cumulating contribution of about6.3%. The space distribution ofcorrelation coefficient show that East China Sea is about0.7, the esat and south ofTaiwan island is0.4-0.6, and Taiwan strait is under0.2.The thermosteric sea level of ECS contributes80%or so to T/P sea level, thekuroshio trajectory50%, and the remaining under50%. There are certain contributionwithin the year.The controlling and sensitive experiment is carried out in ECS using ROMS, theresult show the sea level still reflect seasonal variation, but the process alleviate. In getting rid of the forcing of wind, the variation of sea level disappears in MZCF(MinZhe current coastwise), and the change recedes from seacoast to ocean. The middlesea level is higher in spring and lower in autumn disappear. Gradual change of annualrange nearly disappear from seacoast to ocean, the annual range is almost same inECS. The radio of annual range between including wind forcing and getting rid ofwind forcing decrease gradually from seacoast to ocean.