2009年7月辽宁3次局地短时暴雨过程对比分析

Comparison on three local short-time heavy rains in July,2009 in Liaoning province

利用常规观测资料、自动气象站降水资料和NCEP1°×1°资料,对2009年7月辽宁省3次局地短时暴雨的500 hPa位势高度场、垂直速度场、sθe场和水汽通量场进行对比分析。结果表明:3次局地暴雨过程中,辽宁西部和北部的暴雨落区与上升速度中心对应,而辽宁东南部暴雨落区位于上升区边缘;露点锋、中α尺度低压和暖式切变线对三次短时暴雨过程起到触发作用;当T639降水产品预报降水时段内有大范围的小雨天气,说明将有弱的天气尺度强迫出现,此时应重点分析水汽辐合、高能舌和上升速度大值中心叠加的区域;如果该区域存在中尺度系统触发机制,则该区域可能是局地暴雨的落区。

Based on the conventional observation data, precipitation data from automatic stations and NCEP reanalysis data （ 1°×1° ） from NCEP/NCAR center, geopotential height field at 500 hPa, vertical wind velocity field, θse field and vapor flux divergence field of three local short-time heavy rains in July, 2009 were compared. The results show that the falling areas of three local heavy rains in the western and northern Liaoning province correspond with the locations of high ascending velocity centers, while those in the southeastern Liaoning province locate in the edge of high ascending velocity regions. Dew-point front, meso-α-scale low pressure and warm shear line are the direct reasons forming three local short-time heavy rains. It suggests that weak weather forcing occurs when it rains in most regions according to T639 forecast production. The superposition regions of vapor conver- gence, high-energy tongue and ascending velocity large value center should be considered at this time. If there is a trigger mechanism of mesoscale system in such area, it will probably be the falling area of local heavy rain.