大连两次台风暴雨过程对比分析

利用常规气象资料、加密气象自动观测站资料及NCEP再分析资料对2017年8月3日和2012年8月3日发生在大连地区的“海棠”(1710)和“达维”(1210)两次台风暴雨过程进行对比诊断分析。通过对台风路径、环流形势、双台风相互作用等方面进行对比分析。结果表明:这两次台风暴雨过程的降水系统为典型的双台风降水模型,在两个台风的北部都有不同强度的冷空卷入,触发对流不稳定,有利于中尺度暴雨云团的发展。低层850hPa上均有不同程度的切变辐合,高空有急流的建立;两次过程主要降水时段内强降水中心从低层到高层均出现了强烈的上升运动,暴雨中心上空维持着高层辐散、低层辐合。日本海南部存在台风迫使副热带高压转为径向型或形成阻塞高压,双台风或三台风与副热带高压之间形成的低空急流为暴雨的生成和维持提供了有利的动力条件和水汽条件。台风“海棠”残余环流与高空槽相结合,高空槽带来的冷空气更加强烈,锋生效果更加明显,这种情况更有利于强对流的发生发展。台风“苏拉”与影响大连的台风“达维”相互作用导致强降水阶段暖湿气流更加旺盛,降水持续时间更长,范围更广。

Comparative analysis of two typhoon rainstorm processes affecting Dalian city

In this paper,the data from the conventional meteorological stations,the intensively meteorological automatic observation stations,and the NCEP (National Centers for Environmental Prediction) reanalysis were used to comparatively diagnose and analyze the typhoon and rainstorm processes,Haitang (1710) and Damrey (1210),which occurred in Dalian on August 3,2017 and 2012,respectively.Through analyzing the typhoon track,circulation situation,and interaction between the two typhoon systems,it is shown that the precipitation system during the two rainstorm processes is a typical double-typhoon precipitation mode.In the north of the typhoon systems,there are cold air with different intensities invading and triggering convective instability,which facilitates the development of mesoscale rainstorm cloud clusters.There is a shear convergence at the lower 850 hPa,and a jet stream developing at the upper level.During the main rainfall periods, a strong upward movement from the low to the high levels occurs over the heavy precipitation center,and the divergence at a high level and convergence at low level are maintained over the rainstorm center.The typhoon system existing at the south of Japan sea forces the subtropical high to develop a radial distribution or to form a blocking high.The jet at low level formed between the two or three typhoons and the subtropical high provide favorable dynamic and water vapor conditions for the formation and maintenance of the rainstorms.Combined with the residual circulation of typhoon "Haitang" and the high trough,the cold air brought by the high trough is more intense and the effect of frontogenesis is more obvious,which is favorable to the occurrence and development of strong convection.The interaction between typhoons "Sula" and "Damrey" affecting Dalian leads to more vigorous warm and wet airflow,longer duration and a wider range of precipitation during the heavy precipitation stage.