川滇农牧交错带极端降水的时空演变及突变分析

Spatio-Temporal Variation and Mutation Analysis of ExtremePrecipitation in the Sichuan-Yunnan Agro-pastoral Ecotone

采用川滇农牧交错带内分布较均匀、无缺测站点的1971-2015年逐日降水资料,借助泰森多边形、趋势分析、Mann-Kendall、滑动T检验、反距离权重空间插值(IDW)等方法,研究该区域极端降水的时空演变特征及突变.结果表明,川滇农牧交错带全区域强降水量(R95pTOT)、强降水日数(R95pD)、一日最大降水量(RX1day)、五日最大降水量(RX5day)均呈上升趋势,松潘高原强降水日数为各区域最高,而横断山区除强降水日数外,其他各极端降水指数均大于松潘高原和川西高原,同时,川西高原各指数年际变化比松潘高原和横断山区更剧烈.R95pTOT与R95pD上升的大值区均集中在川西高原东部和横断山区东部,下降大值区均分布在横断山区西南部;RX1day,RX5day随着持续时间的延长,极端降水量的下降区有明显的扩大,而上升区有明显的缩小.典型站点理塘站和木里站极端降水指数发生突变的时间较接近,大致在20世纪70-80年代.

In this paper,no-missing daily precipitation data during 1971-2015 fromuniformly distributed stations in the Sichuan-Yunnan agro-pastoral ecotone were used to investigate the spatial and temporal evolution and mutation characteristics of extreme precipitationin this region with the Thiessen polygons method,trend analysis,Mann-Kendall test,running t test and inverse distance weight spatial interpolation method.The main results were as follows.In the period from 1971to 2015,the regional average of R95pTOT,R95pD,RX1day,and RX5day were allon the rise.R95pD in the Songpan Plateau was higher than that in any other regions.In the Hengduanmountains,except for R95pD,all the other extreme precipitation indexes were larger than those of the Songpan Plateau and the Western Sichuan Plateau.The changes of these indices in the Western Sichuan Plateau were greater than those of the Songpan Plateau and the Hengduanmountains.The large value areas of rising R95pTOT and R95pD were concentrated in the eastern part of the Western Sichuan Plateau and the eastern part of the Hengduanmountains,and the large value areas of decline were distributed in the southwest of the Hengduanmountains.With the increase of duration from RX1day to RX5day,the areas where extreme precipitation decreased expandedsignificantly while the area where extreme precipitation increased narrowedsignificantly.The mutation events of extreme precipitation indexes in Litang station and Muli station occurred around the same timeframe,i.e.in the 1970s and the 1980s.