祁连山区2006年夏季降水过程的天气分析

以500hPa盛行气流为主，将2006年7月17日～8月24日祁连山区的31次降水过程作天气分型。取30—45°N范围500hPa、110°E的格点平均位势高度减90°E平均位势高度的值为分类标准。分成3个主型：西南气流型、西北气流型和平直西风气流型。西南气流型又分移动型和阻塞型2个副型。西北气流型分西北气流冷平流型和冷涡2个副型。用试验区中尺度自动站网的降水资料，分析产生降水过程各天气类型的环流特征及其降水强度。发现2006年夏季祁连山南坡的总降水量比北坡同高度约多44％，而气候平均状况和2007年则北坡大于南坡。2006年祁连山区500hPa盛行西南风，而2007年盛行西北风。

Synoptic Analysis of Precipitation Processes in Summer of 2006 over Qilian Mountains

Thirty - one cases of precipitation process in July to August of 2007 over Qilian mountains have been classified using the dominant air currents at the level of 500 hPa and cloud patterns of FY - 2D satellite images. The difference between the 500 hPa average geopotential height for grid point on 110°E （H1） and that on 90°E （H2） in the range of 30°N - 45°N was used as criterion of classification, and the precipitation processes have been classified as three main types, including southwest air current, northwest air current and flat west air current type. Southwest air current type is also divided into moving and blocking two subtypes and northwest air current type into cold advection and Hetao cold vortex two subtypes. Using precipitation data from automated weather stations in the experimental region, the circulation characters and precipitation intensity for each synoptic type have been analyzed. It is found that the total precipitation of the south slope is more than that of the north slope about 44% in the same sea level elevation in summer 2006 over Qilian mountains, but for climatic state and the year of 2007, the total precipitation of the north slope was more than that of the south slope, and the dominant southwest wind in 2006 but northwest wind in 2007 at the level of 500 hPa over Qilian mountains.