云南两次局地暴雨过程水汽输送特征分析

Analysis the Characteristics of Water Vapor Transport of Two Local Heavy Rain Processes in Yunnan Province

采用常规观测资料、NCEP再分析资料,结合数值试验,对2012年5月24日和2015年9月27日云南两次局地暴雨过程水汽输送特征进行分析。结果表明:①两次过程主要受副热带高压影响,强降雨及其水汽输送伴随副热带高压西伸而中断,“5.24”过程动力条件主要由天气尺度系统提供,“9.27”过程动力条件主要为地形抬升作用;②两次过程水汽源地均为孟加拉湾、南海、西太平洋,“5.24”过程以西南路径水汽输送为主,输送距离较远,“9.27”过程以东南路径水汽输送为主,输送距离较短,局地特征更显著;③“9.27”过程水汽通量及最大雨量值均高于“5.24”过程,水汽通量与强降雨相关性较好,对强降雨具有一定指示意义;④两次过程水汽输送均集中在600 hPa以下层,以经向偏南水汽输送为主,水汽输送增强时间较强降雨开始时间提前48~72 h;⑤数值模拟结果与常规分析一致,同时可显示水汽垂直输送特征,低层以偏南路径为主,中层西南路径增多,中层以上出现偏西路径,存在沿西风带来自印度半岛及青藏高原的水汽贡献。

Based on the conventional observations,NCEP reanalysis data and numerical test,water vapor transport characteristics of two local rainstorm processes in Yunnan on May 24,2012 and September 27,2015 are analyzed.The results show that:①The two processes are mainly affected by the subtropical high,the heavy rainfall and its water vapor transport are interrupted due to the extension of the subtropical high,the dynamic condition of the“5.24”process are mainly provided by the weather scale system,the dynamic condition of the“9.27”process is mainly used for the terrain uplift;②The water vapor sources of the both processes are the bay of Bengal,the South China Sea and the Western Pacific,the"5.24"process was dominated by water vapor transport in the southwest,the conveying distance is long,the"9.27"process was dominated by water vapor transport in the southeast,the conveying distance is short,the local characteristics are more significant;③"9.27"process’s water vapor flux and maximum rainfall are higher than that of"5.24"process,the correlation between water vapor flux and heavy rainfall is good,it has a certain indication significance for heavy rainfall;④The water vapor transport of the two processes was concentrated in the layer below 600 hPa,the water vapor is mainly transported from meridional to southerly,the intensive time of water vapor transport is earlier than the beginning time of rainfall 48 to 72 hours;⑤The numerical simulation results are consistent with the conventional analysis,at the same time,the vertical transport characteristics of water vapor can be displayed,the lower layer is mainly southward,the number of middle-level southwest paths increased,there is a westward path above the middle level,there is a contribution of water vapor from the Indian peninsula and the Tibetan Plateau along the westerly belt.