长江源区气温降水变化趋势及其对区域干旱的影响

Variation trend of temperature and precipitation in source region of Yangtze River and its influence on regional drought

长江源区是受全球气候变化影响的敏感地区。为研究气候变化对其区域干旱的影响,采用了TFPW-MK趋势检验法,对20世纪50年代以来长江源区气象站降水量、气温的变化趋势进行了显著性检验,识别了各季节和月份的变化特点,采用了标准化降水蒸散发指数(SPEI)作为反映区域干旱的指标,对年尺度、月尺度长序列变化趋势进行了分析,通过气温-潜在蒸发相关性分析,研究了降水、气温变化对区域干旱的影响。结果表明:①长江源区年降水量增加趋势显著,各站点年降水增加幅度平均为0.31%/a,增加的月份主要集中在4月和5月;②各站点年平均气温、最高气温和最低气温变化均存在显著增加趋势,平均每年增加1.55%、0.49%和0.59%;③月尺度气温与潜在蒸发序列间相关性较高(0.8以上),表明气温是SPEI干旱指标演变的重要驱动因素,长江源区上游(五道梁、沱沱河站)干旱呈现加剧趋势,而下游(曲麻莱站)干旱呈现减轻趋势。

The source region of the Yangtze River is a sensitive region affected by global climate change.In order to study the impact of climate change on regional drought,in this paper,TFPW-MK trend test method is used to test the significance of the variation trend of precipitation and temperature of the meteorological stations in the source re⁃gion of the Yangtze River since the 1950s.The seasonal and monthly variation characteristics are identified.The standardized evapotranspiration index(SPEI)is used as an index to reflect the regional drought.Through the corre⁃lation analysis between temperature and potential evaporation,the influence of precipitation and temperature on re⁃gional drought is studied.The results show that:the annual precipitation in the source region of the Yangtze River increases significantly,with an average increase rate of 0.31%/a,and the increasing months are mainly concentrat⁃ed in April and may;the annual average temperature,maximum temperature and minimum temperature increase significantly,with an average annual increase of 1.55%,0.49%and 0.59%for the the stations.The correlation be⁃tween temperature and potential evaporation is high and temperature is an important driving factor for the evolution of SPEI drought index.The upper reaches(Wudaoliang and Tuotuohe)of the source region of the Yangtze River shows an increasing trend of drought,while the lower reaches(Qumalai and Yushu)shows a decreasing trend of drought.