红河流域1960-2007年极端降水事件的时空变化特征

利用中国境内红河流域23个气象站点1960-2007年的逐日降水数据,基于极端降水指数分析流域极端降水事件的时空变化特征。结果表明:极端降水频次和强度表现出从东南向西北递减的特征,高值区分布在江城-绿春-金平-河口一线以南,低值区分布在巍山-南涧-弥渡一线以北及元江中游河谷;极端降水频次峰值出现在7月,汛期极端降水出现频次占全年的91.48%。1960-2007年期间,极端降水指数均表现出上升趋势,其中,极端降水贡献率和平均日降水强度上升趋势较为显著,线性趋势值分别为0.68%·(10 a)^-1和0.17 mm·d^-1·(10 a)^-1。除了平均日降水强度整体上表现出上升的趋势外,其余5个极端降水指数趋势变化具有空间差异性,增加的站点大多分布在李仙江上游、 元江中上游和藤条江流域,减小的站点大多分布在李仙江下游、 元江下游和盘龙河流域。

Spatial and Temporal Variations of Extreme Precipitation Events in the Red River Basin during 1960-2007

The temporal and spatial variations of extreme precipitation were studied by using extreme precipitation indices Based on the daily precipitation data of 23 meteorological stations over the Red River Basin in China from 1960 to 2007. The intensity and frequency of extreme precipitation gradually reduces from southeast to northwest, high value area was distributed along the south of the Jiangcheng-Lüchun-Jinping-Hekou while low value area existed along the north of Weishan-Nanjian-Midu and the middle reaches of the Yuanjiang River Valley. The peak of extremely heavy precipitation occurred in July, while extreme precipitation occurrence frequency in flood season accounted for 91.48% of the annual total. In the past 48 years, an increasing trend was observed in indices such as the total wet day precipitation (PRCPTOT), the maximum 1-day precipitation amount (Rx1d), the maximum 5-day precipitation amount (Rx5d), the number of heavy precipitation days (R95N), the percent of total precipitation from heavy precipitation (R95T) and the simple daily intensity index (SDII), among which R95T and SDII increased significantly at the rates of 0.68%·(10 a)^-1 and 0.17 mm·d^-1·(10 a)^-1 respectively. The trends of these indices exhibited spatial differences except for SDII, regions with the increasing trends are distributed mostly in the upstreams of the Lixianjiang and Yuanjiang rivers, as well as Tengtiao River Basin, while those of the decreasing trends were found in the downstreams of the Lixianjiang and Yuanjiang rivers, and Panlong River Basin as well.