热带气旋生成前初始中、低层型涡旋的热力结构发展差异OA

By analyzing actual typical cases,the differences in development and roles of initial mid-level(MV)vortices and low-level(LV)vortices during tropical cyclone(TC)genesis were examined.During the early stage of the MV-type TC Koinu,a persistent positive temperature anomaly existed,which was not observed in the LV-type TC Mawar.In addition,the warm core appeared earlier in Koinu than in Mawar.The initial warm core was at a lower altitude in Mawar than in Koinu.When the warm core was strengthened to the same extent,the low-level winds in Mawar intensified more rapidly than in Koinu,thereby enhancing the radial gradient of the sea level pressure,generating stronger low-level radial inflow,which was more favorable for TC intensification.At the same time,the initial mid-level cold anomaly in Koinu also inhibited its intensification.The appearance of the warm core in Mawar was closely related to the subsidence induced warming process,which did not occur in Koinu.Therefore,the difference of initial altitudes of the warm cores in Mawar and Koinu ultimately led to a higher TC genesis efficiency(the occurrence of warm core as the start time in the definition)for Marwar compared to Koinu.Moreover,the warm cores in both Koinu and Mawar appeared prior to obvious intensification and reaching the level of tropical storm,which indicated that the warm core is a prerequisite for TC genesis.