THE CHARACTERISTICS OF AIR-SEA HEAT FLUX EXCHANGE DURING THE GENERATION AND DEVELOPMENT OF THE LOCAL TYPHOON OVER THE SOUTH CHINA SEA

A South China Sea(SCS) local typhoon(SLT) is defined as a tropical cyclone(TC) that forms within the SCS region and can reach the grade of tropical storm(TS) or above.The statistical features of the SLTs from 1985 to 2007 were analyzed first.It was found that the intensities of the TCs were relatively weak and about 68% of them could develop into TSs.The SLT intensity was associated with its genesis latitude as well as its track.The SLT frequency number presented a seasonal variation with two peaks in May and June through September.Based on the daily heat flux data from the Woods Hole Oceanographic Institution_Objectively Analyzed air-sea Fluxes(WHOI_OAFlux) in the same period,the air-sea exchange during the process of generation and development of the SLT was studied.Results showed that the heat fluxes released to the atmosphere were increasing significantly day by day before cyclogenesis.The ocean at the south to the TC center provided the main energy.Along with the development of SLT,the regions with larger heat fluxes spread clockwise to the north of TC,which reflected the energy dispersion property of vortex Rossby-waves in peripheral bands of TC.However,once the SLT was formed there were no more increments in the fluxes.During the whole process,the net heat,latent heat and sensible heat flux displayed a similar evolution when the latent heat made a main contribution to the net heat flux.The maximum air-sea heat exchange always locates at the left side of the TC moving direction,which may reflect influence of the SCS summer monsoon on TC structure.