中尺度暴雨过程中地形抬升作用分析

Analysis of the Topographic Lifting in Mesoscale Rainstorm Process

利用精细的地形数据、自动气象站和局地同化资料,对湖北2008年汛期10次暴雨过程中的地形抬升作用进行了统计分析。结果表明,地形抬升对暴雨的作用十分重要,一方面可使湿空气的凝结加强,降水强度加大;另一方面,在有利的大尺度环流背景下,可成为不稳定能量释放的触发机制,激发中尺度暴雨。同时指出,在这10次暴雨过程中并非每个出现暴雨的站点都有地形抬升作用,地形抬升只是其触发和增强的充分条件,而非必要条件。但在有利的大尺度环流背景下,地形抬升作用与多种中尺度特征物理量场的友好搭配是强降水短时临近预报的途径之一。

The fine topographical data,automatic weather station data and the local assimilation materials were utilized to analyze ten heavy rain falls in Hubei in 2008.The results showed that the topographic lifting played an important part in heavy rains in that topographic forcing makes air condense and strengthened the precipitation.On the other hand,under the beneficial large-scale circulation background,as the trigger mechanism of unstable energy,topographic lifting can excite the mesoscale heavy rain.It was pointed out that heavy rain occurred not every site had the role of terrain elevation.Terrain elevation was sufficient to trigger and enhance the conditions of the mesoscale heavy rain.Under beneficial circulation background,a good way to predict the short-time and heavy rainfalls was to combine the topographic lifting with many other physical variables that could reflect the mesoscale characters.