The air-sea heat exchange at Xisha areas during the onset of southwest monsoon in 2000

Using the observational data of the Second SCS Air-Sea Flux Experiment on the Xisha air-sea flux research tower during May 7 to June 17,2000,the radiation budget,latent and sensible heat fluxes and net oceanic heat budgets before and after summer monsoon onset were calculated.It is found that there are considerable changes on air-sea fluxes,especially on latent heat fluxes and net oceanic heat budget after summer monsoon onset.Furthermore,the analyzed results of five synoptic stages are compared and the special characteristics of flux transfer during the different stages around onset of SCS monsoon are discussed.The fluxes change shows that there is an oceanic heat accumulating process in pre-onset and break period and an oceanic heat loss process in the onset period.Also the latent fluxes and water vapor transported to continent can be influenced by the duration and intension of the southwester especially,further influence on the rainfall appearance in China continent.Finally,through comparison of the Xisha fluxes with those obtained from Indian Ocean and western Pacific Ocean,their differences may be seen.It can explain why after monsoon onset,the SST can keep stable values over the SCS while over the Arabian Sea and the Bay of Bengal they decrease quickly.