相似台风"纳沙"和"海鸥"在雷州半岛产生的降雨差异及其可能机制研究OA北大核心CSTPCD

This study examined the differences in rainfall characteristics and possible mechanisms behind such differences for two typhoons,Nesat(1117)and Kalmaegi(1415),which followed similar paths over the Leizhou Peninsula(LP).Utilizing data from conventional meteorological stations,regional automated weather stations,radar observations,and ERA5 reanalysis,the present study analyzed the distinct patterns of rainfall induced by these typhoons.The results showed that the total rainfall and maximum rainfall of Typhoon Nesat were 1.5 and 2.4 times higher than those of Typhoon Kalmaegi,respectively.The total rainfall of Typhoon Nesat included both rainfall from the typhoon circulation and the typhoon trough,while Typhoon Kalmaegi only had rainfall from the typhoon circulation.The major reasons for such differences were as follows:after the landfall of Typhoon Nesat,the South Asian High and the Subtropical High broke into the eastern and western parts,resulting in a strong high-level divergence over the LP area,and the southwesterly and southeasterly currents converged into the southerly at the low level.Meanwhile,the frontal area facilitated the intrusion of cold air from 850 hPa and below into the typhoon trough of Typhoon Nesat,and the baroclinic effect intensified convection.After the weakening of the typhoon circulation,the low-level convergence in the LP area strengthened again,which in turn created favorable conditions for rainfall and led to the intensification of rainfall in the typhoon trough.By contrast,after Typhoon Kalmaegi made landfall,the LP region was affected by the enhancement and southward movement of the South Asian High and the Subtropical High,and the low-level convergence in the LP area quickly changed to divergence after the weakening of the typhoon circulation.The downward airflow inhibited the development of convection,resulting in minimal rainfall formation in the typhoon trough.Moreover,it was also found that the topography of the LP affected the location of typhoon rainfall centers,which were usually identified on the windward slopes southeast of the LP's three peaks.These results may facilitate the forecasting and diagnosis of typhoon rainfall affecting the LP.