近50年来西藏极端降水时空变化特征

利用1961~2010年西藏地区9个气象站点逐日降水资料,结合百分位方法定义的极端降水阈值,分析了该地区极端雨日及其平均降水强度、不同持续时间的极端降水事件、气候变化对极端降水的时空变化特征的影响。结果表明:(1)92°E以西的地区,极端雨日平均降水强度呈现出增加的趋势,而在92°E以东的地区,呈现出减小的趋势;(2)极端降水事件以持续1 d为主,其频率一般在4.3次/年以上,强度一般在20 mm/d以上,林芝站和波密站为频率和强度高值区;(3)气候变化背景下,极端降水的频率、强度表现出西移的态势。

Spatio-temporal variation characteristics of extreme precipitation events in Tibet in last 50 Years

Based on the daily precipitation data of 1961~2010 from 9 meteorological stations in Tibet and combined with the threshold of extreme precipitation defined by the method of percentiles，the impacts from the extreme precipitation days and their mean precipitation intensities，the extreme precipitation events with various durations and the climate changes on the spatio-temporal variation characteristics of extreme precipitation events in the region are analyzed herein. The results show that（1）in the region to the west of 92°E，the mean precipitation intensities of the extreme precipitation days present an increasing trend，while they show a decreasing trend in the region to the east of 92°E;（2）the durations of the extreme precipitation events are mainly 1 d with the frequencies of 4.3 times/a year and the intensities of 20 mm/d or above generally，while Linzhi and Bomi meteorological stations are located in the high value zones of the frequency and the intensity;（3）under the background of climate change，the frequencies and intensities of the extreme precipitation events exhibit a tendency of moving to the west.