黄河上游玛曲地区近40a蒸发量变化特征分析

利用黄河上游玛曲气象站1969-2008年的蒸发量观测资料,用线性趋势分析、小波分析及突变分析等方法,分析了玛曲近40a蒸发量的变化特征。结果表明:近40a来玛曲年蒸发量呈较为明显的减小趋势,倾向率为-44.3mm/10a,其中90年代这种减小的特征更为突出。玛曲年蒸发量存在较为明显的准10a周期变化和25a较长周期变化特征。年蒸发量在1974年发生了由高向低的突变。40a中玛曲各季节蒸发量普遍呈减小的趋势,其中尤以夏季蒸发量减小的趋势最为明显,春季蒸发量变化较平缓,减少的趋势在各季节中表现最微弱。通过对蒸发量与环境因子之间的相关关系分析表明,气温日较差和风速是影响蒸发量的最重要的因子,气温日较差和风速的明显减小,可能是引起蒸发量下降的主要原因。

Change features of pan evaporation in Maqu area in the upper reaches of Yellow River in recent 40 years

Pan evaporation characters in Maqu area in the upper reaches of Yellow River in recent 40 years were analyzed by using linear regression,abrupt change analysis and wavelet analysis.The results showed that annual evaporation decreased-44.3mm/10a,especially in the 1990s,the evaporation decreased by more obviously.There were 10 years and 25 years of change cycle of annual evaporation.The annual evaporation abrupt changes occurred from high to low in 1974.The seasonal evaporations were generally decreased in recent 40 years,especially in summer,Evaporation decreased even more.Evaporation was slight decreased in spring.The influences of the diurnal temperature range and wind speed changes on pan evaporation change were dominant,they were the primary reasons for the decreasing of pan evaporation in Maqu in the past 40 years.