2106号台风“烟花”的路径及降水特点分析

The path and precipitation characteristics of"In-Fa"in typhoon 2106

2106号台风“烟花”(In-Fa)在浙江省两次登陆,影响时间从7月22日一直持续到28日,受其影响,浙江过程累积面雨量及单站雨量均破登陆浙江台风历史记录。通过分析发现:台风时段副热带高压位置比常年同期异常偏北,导致引导气流很弱,是造成台风“烟花”移速缓慢甚至在原地回旋的直接原因。2107号台风“查巴卡”和2108号台风“尼伯特”与台风“烟花”无直接互旋作用,而是通过对副热带高压强度和范围的影响,间接对台风“烟花”路径产生影响。西南季风向台风“烟花”持续输送水汽,是其登陆后强度得以维持的原因,台风在杭州湾长时间逗留,水汽供应有利于强度的维持。台风西侧云系在浙江上空受干侵入影响,减弱非常明显,形成非对称结构。对流有效位能很小,影响对流发展,小时雨强普遍较小,但由于台风“烟花”影响时间是一般台风的2倍,故累积雨量大。后期边界层辐合线的形成触发了对流的发展。地形对降水的增幅非常显著,累积雨量大的站点通常都位于海拔较高的山区,地形增水作用下站点雨量可达其他站点的2~3倍。

The 2106 typhoon"In-Fa"landed twice in Zhejiang Province with its impacts lasting from July 22 to 28,the cumulative rainfall and single station rainfall in Zhejiang Province broke the historical record of typhoon in Zhejiang Province.Through this analysis,we find that the position of subtropical high during the period of the typhoon is abnormal norther than that in the climatology,which leads to a weaker guiding airflow further resulting in the slow movement speed of the typhoon"In-Fa".Typhoon 2107"Chabaka"and typhoon 2108"Nibert"have no direct interaction with the typhoon"In-Fa",but pose indirectly effect on the path of the typhoon"In-Fa"through affecting intensity and range of subtropical high.Continuously water vapor supplying to typhoon"In-Fa"by the southwest monsoon sustains the intensity of the typhoon"In-Fa"after landing,creating advantage condition for the long duration in Hangzhou Bay.The cloud system on the west side of the typhoon"In-Fa"encounters dry air over Zhejiang Province,leads to the weakening of the typhoon and forms an asymmetric structure.The convective available potential energy is low,thus limit the development of vertical convection and the intensity of hourly rainfall.The lasting period of the typhoon"In-Fa"is twice of those of general typhoons,so the cumulative rainfall is large.The increase in precipitation induced by land surface elevation is very significant.Stations with high cumulative rainfall usually locate in montanic areas with high altitude,and the rainfall reaches 2~3 times of those of other areas.