山东半岛两次秋季台风远距离大暴雨的特征分析

Characteristics of two torrential rainfall processes in Shandong Peninsula in autumn under the remote effect of typhoon

利用常规观测资料和NCEP/NCARFNL资料对“狮子山”(1006)和“天兔”(1319)两个台风造成山东半岛秋季远距离大暴雨的特征进行了诊断分析。结果表明:1)造成两次大暴雨的天气形势和物理量特征有相似,也有差异。2)两个台风的生成源地、移动路径以及强度差别均很大,大暴雨发生在台风登陆后从广东移到广西的过程中,高空北支冷槽、台风倒槽和850hPa切变线是造成山东半岛大暴雨的主要天气系统。3)台风东侧和副热带高压之间850hPa偏强东南气流将东海、黄海的水汽源源不断输送到山东半岛并在此辐合;低层辐合、高层辐散和垂直上升运动均利于大暴雨的发生;大暴雨发生前大气处于不稳定大气层结;台风和中纬度系统相互作用形成两层或三层锋区的斜压性特殊结构及高空急流的增强是山东半岛秋季台风远距离大暴雨的重要特征。4)两次大暴雨过程中低空急流特征、锋区斜压性结构特征、不稳定大气层结特征存在较大差异。

The characteristics of two torrential rainfall processes in Shandong Peninsula in autumn affected by distant Typhoon LIONROCI(2010)and Typhoon USAGI(2013)respectively are diagnosed and analyzed by using conventional observation data and NCEP/NCAR FNL data.The results are as follows.1)The synoptic situations and physical parameters that caused the two torrential rainfall processes are of similarities and differences.2)There are significant differences in the origins,tracks,and intensities for the two typhoons.The heavy rainstorm happens as the typhoons move from Guangdong to Guangxi after their landings,the upper northern cold trough,typhoon inverted trough,and shear line at 850 hPa are the main synoptic systems leading to the rainstorms in Shandong Peninsula.3)The stronger southeastern air flow between the east side of the typhoon and subtropical high continuously transports water vapor from the East China Sea and the Yellow Sea to Shandong Peninsula where the water vapor forms convergence;the convergence at lower layer,divergence at upper layer,and vertical ascending motion are favorable for the occurrence of the torrential rainfall;the atmospheric stratification is unstable before the rainstorms;the baroclinic structure in two-layer or three-layer frontal zone produced by the interaction between typhoon and synoptic system in the middle latitude and the intensification of upper-level jet stream are significant characteristics of the torrential rainfall in Shandong in autumn under the remote effect of typhoons.4)For these two rainstorms,there are major differences in characteristics of low-level jet stream,baroclinic structure in frontal zone,and unstable atmospheric stratification.