祁连山及周边地区降水与地形的关系

利用祁连山区及其周围(90°～104°E,32°～42°N)1960—2004年55个气象站点白天08:00—20:00时、夜间20:00—08:00时和全天20:00—20:00时逐日降水资料,分析了不同降水强度的时空分布特征及其与海拔的关系,得出了不同降雨强度以及不同季节最大降水总量出现的海拔.小雨日数与海拔较为密切,呈线性增长;中雨以上与坡向、地理位置有关,在海拔4850m附近降雨日数最多为143d.降雨日数和总量在海拔3700m左右达最大峰值,而在海拔2700m附近为次大峰值.进一步利用干湿年资料诊断分析出祁连山区最大降水高度的出现除了受地面海拔的影响外,很可能与高低空两个最大相对湿度中心及相应较强的冷空气活动中心出现高度关系密切.

Relationship between Precipitation and Terrain over the Qilian Mountains and Their Ambient Areas

Daily precipitation observations of 08:00～20:00 in daytime, 20:00～08:00 in nighttime and 20:00～20:00 in the whole day from 55 meteorological stations during 1960-2004 over the Qilian Mountains and their ambient areas (90°～104° E, 32°～42° N) are primarily analyzed to study the temporal and spatial distributions of precipitation in different categories of intensity, the frequency and intensity of precipitation and their relations to elevation. The elevations of maximum total rainfall for different precipitation's intensities and seasons are found out. The frequency of flurry days linearly increases well with elevation over the Qilian Mountains. However, the days of middle rain and others have something to do with slopes and geographic locations. The maximum days of rainfall are 143 d at the elevation of 4 850 m. The first peak of total rain days and the total rainfall is at the elevation of 3 700 m or so, and the second peak of that is at the elevation of 2 700 m or so. Furthermore, it is diagnosed from the data of drought and wet years that the elevation of maximum rainfall is possibly dependent on the two maximum relative humidity centers and the elevation of the corresponding stronger cold air activity center, except for the effect of ground altitude.