怀化市一次大暴雨过程分析

Analysis of a heavy rainstorm process in Huaihua

利用NCEP再分析资料(分辨率:1°×1°)、常规观测资料及区域自动站降水资料,对2015年7月22日至23日出现在怀化的一次大暴雨天气过程进行分析。结果表明:这次过程是由高空低槽带动中低层低涡切变东移所引发的,强降雨区850 hPa水汽通量大、水汽辐合剧烈,且比湿在15 g/kg以上;低层正涡度、高层负涡度及低层辐合、高层辐散的形势利于强降雨的发生,强降雨出现在850 hPa能量锋区前缘假相当位温大值区与700 hPa强垂直上升速度重叠的区域;另外,地形动力作用对这次大暴雨过程有一定的影响。

The heavy rainstorm process occurred in Huaihua from July 22 to July 23,2015 was analyzed by using NCEP re-analysis data,conventional observation data and regional automatic station precipitation data.The results showed that this process was caused by the eastward movement of the middle-and lower-level vortex shear driven by the upper-level trough.The water vapor flux at 850 hPa was large,the water vapor convergence was intense,and the specific humidity was above 15 g/kg in the heavy rainfall area.The situation of positive vorticity at the lower level with negative vorticity at the upper level,and convergence at the lower level with divergence at the upper level was favorable to the occurrence of heavy rainfall.The heavy rainfall occurred in the overlap area of pseudo-equivalent potential temperature large value at the edge of 850 hPa energy front and the strong vertical rising velocity of 700 hPa.In addition,the topographic dynamic effect had a certain impact on the heavy rainstorm process.