河西走廊西部近41年5—9月降水特征分析

Analysis of precipitation characteristics in the west of Hexi Corridor from May to September in recent 41 years

利用位于河西走廊西部的酒泉市7个国家自动气象站1976—2016年5—9月逐日20:00—20:00降水资料,运用统计学方法,研究酒泉市降水雨日、雨量以及极端降水事件的时空分布特征和变化趋势。结果表明,酒泉市小雨雨日最多,占总雨日的82.1%,5—9月雨量将近1/3是由小雨提供的,2/3是由中雨以上的降水提供的。各级雨日(量)的空间分布特点是,最多的是肃北,最少的是敦煌,近41年酒泉极端降水事件绝对强度较小,相对强度较大,暴雨事件频次没有显著的线性趋势,稳定维持在0.1次/年左右,但其年际和年代际波动十分明显,无暴雨事件的时间分布较为分散,在每个年代都有出现,另外在2011—2016年8—9月没有极端降水事件的发生。

Using the daily precipitation data(20:00-20:00)from May to September in 1976-2016 of 7 national automatic weather stations in Jiuquan,located in the west of the Hexi Corridor,using statistical methods,the spatial-temporal distribution characteristics and trends of rainy days,precipitation,and extreme precipitation events in Jiuquan were studied. The results show that Jiuquan has the most mild rainy days,accounting for 82.1% of the total rainy days. Nearly 1/3 of the rainfall in May-September is provided by mild rain,and 2/3 are provided by precipitation above moderate rain. The spatial distribution characteristics of rainy days(quantities)at all levels are:the most is Subei,the least is Dunhuang. Meanwhile,the absolute intensity of Jiuquan extreme precipitation events in the past 41 years is relatively small and the relative intensity is large. There is no significant linear trend in the frequency of heavy rainfall events,and it has remained stable at about 0.1 times per year. However,its inter-annual and inter-decadal fluctuations are very obvious. The time distribution of no rainstorm events is relatively scattered,and it occurs in every age. In addition,there were no extreme precipitation events in August-September 2011-2016.