新疆极端降水概率分布特征的时空演变规律

Spatial-temporal Evolution Pattern of Probability Distribution Characteristics of Extreme Precipitation in Xinjiang Autonomous Region

依据新疆地区53个雨量站1957-2009年日降水资料,根据研究需要,定义了8个极端降水指标。运用K-S法确定降水指标最适概率分布函数,确定10年一遇极端降水量值;在此基础上,采用Copula非参数估计方法,通过Akaike information criterion(AIC)法确定两降水指标联合分布函数,系统分析1980年以后极端降水单变量极值及降水极值二维联合概率分布特征变化的时空演变特征,研究结果表明:①新疆有湿润化趋势,北疆湿润化趋势比南疆显著;②从降水天数和极端降水天数角度来看,新疆极端强弱降水同时出现的概率减小,从极端降水雨量和强度来看新疆中部、南疆西部、北疆东部及北部极端强弱降水同时出现的可能性减小,而天山西部与南疆北部的可能性增加;③1980年后新疆地区发生涝的概率增大,发生旱的概率减少。

Eight research required extreme precipitation indexes are defined according to daily precipitation data of 53 rain stations in Xinjiang during 1957~2009.Extreme precipitation values of a 10-year return period are confirmed by the fittest probability distribution function determined by Kolmogorov-Smimov method,based on which,joint distribution functions of the two precipitation indexes are determined using Copula non-parameter estimation algorithm and by Akaike information criterion（AIC） method.Single extreme variable of extreme precipitation and spatial-temporal evolution characteristics of dimensional joint probability distribution characteristics changes of extreme precipitation values after 1980 are systematically analyzed.The results show that：（1） Wet tendency is identified in Xinjiang,especially in North Xinjiang.（2） In terms of days of precipitation and of extreme precipitation,the probability of extreme heavy and extreme slight precipitation occur in the same year decreased;in terms of the total extreme precipitation and the extreme precipitation intensity,the probability decreased in the middle of Xinjiang,the west of South Xinjiang and the east and north of North Xinjiang,and increased in west TianShan Mountian and the north of South Xinjiang.（3） After 1980,the frequency of flood increased and that of drought decreased.