两个相似路径台风引发的东部沿海地区降水分布特征及成因对比分析

A comparison analysis of precipitation distribution over the eastern coastal area and their causes between two typhoons with similar paths

利用美国国家环境预报中心的再分析资料和中国气象局观测站点的实况降水观测数据,分析了路径相似的1909号台风“利奇马”(Lekima)和0509号台风“麦莎”(Matsa)影响期间东部沿海地区降水强度和落区的明显差异,对比了两个登陆台风的大尺度环流和动热力结构特点。结果表明:台风“利奇马”与西风槽在山东中西部(台风路径西侧)结合,与高空急流入口区右侧的垂直运动相叠加,形成深厚而强烈的上升运动,台风东侧的低空东南急流持续输送水汽,降水增幅明显且中心偏西,台风减弱变缓;同时,东北亚环流受下游台风阻挡稳定少动,降水系统长时间维持是造成突破历史记录极端降水的又一重要原因。与台风“利奇马”不同,台风“麦莎”影响期间大尺度环流没有西风槽和高空急流活动,低层辐合浅薄且上升运动弱,水汽来自减弱的台风环流;台风移动速度快,是台风“麦莎”降水明显小于台风“利奇马”的原因。

Based on the reanalysis data of the National Centers for Environmental Prediction and precipitation data of the China Meteorological Administration observation stations,the significant difference of precipitation intensity and spatial distribution in the eastern coastal area during typhoon "Lekima"(1909) and typhoon "Matsa"(0509) are analyzed,and the characteristics of the large-scale circulation and dynamic thermal structural of the two landing typhoons with similar paths are compared in this paper.The results show that typhoon "Lekima" combined with the westerly trough in the central and western Shandong province(west of the typhoon path) and the vertical movement on the right side of the high-altitude jet inlet area induces a deep and strong upward movement.The low-altitude southeast jet on the east side of the typhoon constantly transports water vapor,which causes the significant increase of precipitation with a westward center and the slowing down of the typhoon intensity weakening.Meanwhile,the northeast Asian circulation is stable since it is blocked by the downstream typhoon,and the long-term maintenance of the precipitation system is another important reason for the extreme precipitation that breaks the historical record.Unlike typhoon "Lekima",there is no westerly trough and highaltitude jet in the large-scale circulation during typhoon "Matsa".The water vapor comes from the weakened typhoon circulation with shallow low-level convergence and weak ascending movement and the typhoon moves fast,which makes the precipitation during typhoon "Matsa" significantly less than that during typhoon "Lekima".