河西走廊东部降水日数及强度的时空特征

Temporal-spatial distribution characteristics of precipitation event frequency and intensity in east of Hexi corridor

利用1961-2007年河西走廊东部五站逐日降水资料,分析了河西走廊东部不同降水日数及强度的时空演变特征。结果表明：近47年来,河西走廊东部降水量总体呈增加趋势;河西走廊东部总雨日、小雨日、中雨日和大雨日均呈增加趋势,小雨日数增长率最大;其中民勤、古浪、永昌、乌鞘岭雨日呈增多趋势,而凉州区为减少趋势。年降水强度也呈增强趋势,主要体现为小雨和大雨强度的增大,中雨强度有变小的趋势;其中民勤、凉州区、永昌、乌鞘岭降水强度一致为增加趋势,古浪降水强度为减弱的趋势。总雨日、小雨日、中雨日和大雨日数由南向北均呈减少趋势。河西走廊东部降水强度中心在南部山区的古浪,强度最弱的是中部凉州区,20世纪80年代河西走廊东部多小雨事件,90年代2、1世纪初的2001-2007年河西走廊东部多中雨和大雨事件;2001-2007年河西走廊东部小雨、大雨强度最强,而中雨强度最弱。

Daily rainfall data of 5 weather stations in temporal and spatial variation of precipitation events. The east of Hexi corridor from 1971 - 2007 are used to analyze the results show that the precipitation is relatively in an increase trend in east of Hexi corridor; The number of days of averaged rain, light rain, moderate rain and heavy rain in the area increases, and the annual raining days show a significant increasing trend, which is mostly due to the increasing of the days of light rain; The intensity of annual precipitation shows a significant increasing trend due to the increasing of light rain, and the intensity of moderate rain shows a significant decreasing trend; The number of days of averaged rain, light rain, moderate rain and heavy rain in east of Hexi corridor decreases from south to north, and the number of days of averaged rain has a significant increasing trend in Minqin, Gulang, Yongchang and Wushaoling but has a significant decreasing trend in Liangzhou; The intensified centre of annual precipitation is in the southern mountain area of Gulang, while the weakest is in the central part of Liangzhou, and the intensity of annual precipitation shows a significant increasing in Minqin, Liangzhou, Yongchang and Wushaoling, but has a slight decreasing trend in Gulang; The events of light rain are more frequent in 1980s, and the events of moderate rain and heavy rain are more frequent during the period from the 1990s to the period of 2001 - 2007; The intensity of light rain and heavy rain is the strongest, and moderate rain intensi- ty is the weakest in the period of 2001 - 2007.