高寒内流区极端降水的气候变化特征分析

Analysis on the characteristics of climate change in the endorheic area in alpine region based on extreme precipitation index

利用中国气象局1969—2017年高寒内流区25个气象站的日降水资料,分析极端降水的变化特征,结果表明:1969—2017年高寒内流区降水量呈上升趋势,这种上升很大程度上可能是由于夏季降水量增加导致的,且20世纪90年代以后降水量增加趋势更加明显。极端降水指数除连续干旱日数外,均呈不同程度的增加趋势,其年际变化反映出在进入21世纪后高寒内流区降水向强降水量和日数更多、强度更强、极值更大的方向发展。极端降水指数空间差异性明显,连续湿润日数、雨日降水总量、雨日降水强度、单日最大降水量、五日最大降水量、极端降水量和日降水大于10mm日数表现显著增加趋势的台站百分率分别为5%、64%、42%、60%、32%、35%和43%,连续干旱日数表现显著下降趋势的台站百分率为5%。极端降水事件具有一致性,总降水量增加,极端降水的频率、强度、极值也增加,小雨日数增加是降水总量增加的因素之一。极端降水增湿幅度有随海拔升高有增大趋势,高海拔区雨日降水量和雨日天数的增加是极端降水总量增加的主要因素。

Based on the daily precipitation of 25 meteorological stations from 1961 to 2017,the temporal and spatial variations in extreme precipitation events in the endorheic area in alpine region were analyzed.The results showed that the precipitation in study area delineates a significant increasing tendency,such an increase may largely stem from the contribution of the increase in summer precipitation,and the increasing trend of precipitation was more obvious after 1990 s.Except CDD,the extreme precipitation index showed an increasing trend with different degrees,and the precipitation in the endorheic area in alpine region developed to the direction of heavier precipitation,more days,stronger intensity and greater extreme value after entering the 21 st century.The percentage of stations with CWD,PRCPTOT,SDII,RX1Day,RX5Day,R95 and R10 showing a significant increasing trend was 5%,64%,42%,60%,32%,35%and 43%,and the percentage of stations with CDD showing a significant decreasing trend was 5%.Extreme precipitation events were consistent.As total precipitation increased,the frequency,intensity and extreme value of extreme precipitation also increased,and the increase of light rain days was one of the factors contributing to the increase of total precipitation.The humidification amplitude of the extreme precipitation index increases with the increase of altitude.The increase of precipitation and number of rainy days in high altitude area was the main factor for the increase of total amount of extreme precipitation.