近55 a内蒙古极端降水指数时空变化特征

基于内蒙古100个气象站点1960-2014年日降水数据,选取气候变化监测与指数专家组(ETCCDI)推荐的9个极端降水指数,采用Sen’s斜率法和Mann-Kendall非参数统计检验方法以及空间地统计方法,研究了极端降水指数时空演变特征。结果表明:研究区区域平均的全部极端降水指数均呈不同程度的下降趋势,且年际波动显著;分区的年际趋势有所差异,即东部地区潮湿日数(NW)呈增加趋势,其余极端降水指数均呈减少趋势,其中持续干燥指数(CDD)呈显著下降趋势(P<0.05);中部地区所有极端降水指数均呈减少趋势,其中年总降水量(PRCPTOT)减少趋势较明显;西部地区持续湿润指数(CWD)、强降水量(R95)、单日最大降水量(Rx1day)、5日最大降水量(Rx5day)呈减少趋势,其余指数均呈增加趋势。从极端降水指数变化趋势的空间分布特征来看,区域差异显著,总体上呈下降趋势的站点主要分布于内蒙古东部和中部地区,而呈上升趋势的站点主要分布于内蒙古东北部和西部地区。

Spatiotemporal Variation of Extreme Precipitation Indices in Inner Mongolia in Recent 55 Years

Nine extreme precipitation indices recommended by the Climate Change Monitoring and Index Expert Group (ETCCDI) were selected. The Sen’s slope,the Mann-Kendall nonparametric statistical test and Geostatistical Analyst methods were used to study the spatiotemporal variation of these indices based on the daily precipitation data from 100 meteorological stations in Inner Mongolia from 1960 to 2014. The results showed that the average extreme precipitation indices of the study area were in a decrease trend in varying degrees,and their interannual fluctuations were significant. Their interannual trends in the subareas were different,that is,in the eastern area,the wet days (NW) was in an increase trend,and other indices were in a decrease trend,among which the continuous drying index (CDD) was in a significant decrease trend (P < 0. 05);in the central area,all the extreme precipitation indices were in a decrease trend,and the reduction of total annual precipitation was more obvious;in the western area,the continuous wetness index (CWD),heavy precipitation (R95),monthly maximum 1-day precipitation (Rx1 day),and monthly maximum consecutive 5-day precipitation (Rx5 day) were in a decrease trend,and other indices were in an increase trend. Viewing from the spatial distribution of the change trend of extreme precipitation indices,the regional difference was significant. The stations with a general decrease trend of these indices were mainly distributed in the eastern and central areas of Inner Mongolia,and those with an increase trend were mainly distributed in the northeastern and western parts of Inner Mongolia.