滇中地区极端降水时空变化趋势及其成因分析

Analysis of Tendency Variation and Causes of Extreme Precipitation at Central Area of Yunnan province

极端天气和气候事件是对人类社会危害最严重的自然灾害之一。采用滇中地区1961-2006年46个测站逐日降水数据,分别将大雨/暴雨雨量和雨日数、最大日降水量和年日降水量序列99百分位值作为极端降水临界值,用MK秩次检验方法和IDW插值方法比较分析滇中地区极端降水在时空上的变化特征及其成因。结果认为这3种极值算法在该区可以相互验证,在时间上表现为滇中区域平均的极端降水呈不显著上升的变化趋势,在空间上表现为东部多雨地区降水的变化比较缓和而中西部平坝、河谷少雨地区极端降水的变化要强烈一些。滇中地区的降水类型发生了变化,大雨/暴雨量和大雨/暴雨次数增多而其他降水类型减少。小雨雨量和雨日数的减少是滇中地区年降水量和年降水日数减少的主要原因,降水变率加快且强度增大是滇中地区极端降水的变化的原因之一。

The extreme weather and climate events are the most various natural disasters which endanger human society. This paper analyzes the spatiotemporal variation and causes of extreme precipitation with MK ranking test and IDW interpolation at the central area of Yunnan province. The data of this paper is the daily precipitation for 46 years form 1961 to 2006, and the critical values are the heavy and storm precipitation and raining days, the daily maximum precipitation and 99 percentile of the daily precipitation. The results show that the extreme precipitation has an indistinctively ascending tendency in the recently 46 years, the change of extreme precipitate at the dam field and river valley on the central west region than the eastern area and the three algorisms could be validated each other. The types of precipitation have changed. Because the precipitation and times of the heavy and storm rain has ascending tendency but the others has moderating trend. The main causes which decrease the annual precipitation and clays are the decreasing of the light rain at the central area of Yunnan province. The gradually accelerated variability and increased intensity of precipitation are the possible reasons which cause the change of extreme precipitation at the central area of Yunnan province.