Seasonaland Interannual Variation Of The Mixed Layer Heat Budget And Sea Surface Temperature In The South China Sea

Using satellite data and Regional Ocean Modeling System(ROMS)model output,the seasonal and interannual variation of the surface temperature in the South China Sea is analyzed with the cyclostationary empirical orthogonal function(CSEOF)method.The results show that the first and second modes represent the seasonal and ENSO-related variation of the sea surface temperature respectively.The spatial pattern of the first mode shows greater amplitude of the variation in the northern South China Sea.The correlation between the principal component and Nino3 index is less than 30% for the first mode while exceeds 50% for the second mode with Nino3 index 7 months leading.By comparing the model and satellite results,we found the mesoscale processes generally have an insignificant impact on the seasonal variation and ENSO correlation of the surface temperature.The equatorial Pacific temperature anomaly changes the cloud cover and the monsoon strength over the South China Sea through the atmospheric circulation,And then influence the surface temperature of the South China Sea.In El Ni?o,the decrease of cloud cover increases the solar short wave radiation;The weakening of the monsoon reduces the heat loss of the latent heat flux.Short wave radiation and latent heat flux change simultaneously with ENSO,the air-sea process and the mixing layer delayed the response of the surface temperature to ENSO,the vertical process also has some hindrance.The air-sea process in the northern South China Sea is decided by shortwave radiation and latent heat fluxes,but the southern South China Sea is mainly determined by short wave radiation.The main reason is that the strength of winter monsoon in the northern South China Sea is much larger than that in summer monsoon.In addition,because offshore Ekman transport is more obvious in the north of the South China Sea,the cooling effect of the vertical process in the northern South China Sea is stronger than that in the south of the South China Sea.