1979-2015年青藏高原大气可降水量的变化特征

Change Characteristics of Precipitable Water Vapor Over Qinghai-Tibetan Plateau During 1979-2015

利用ERA-Interim再分析资料,计算了1979-2015年青藏高原上空大气可降水量,并分层分析了其空间分布、气候倾向率及年际和年内的变化特征.结果表明:各层可降水量空间分布和气候倾向率的大小值中心位置及区域差异不同,并且有明显的季节差异.通过检验发现1995年为突变年.年均及春、夏和秋季可降水量的平均值为突变年后高于突变年前,而冬季为突变年前高于突变年后.突变年前,年均和四季的可降水量都为上升趋势,突变年后,冬季为下降趋势,其他季节都为上升趋势,突变年前上升趋势速率比突变年后更快.从EOF分析的前3个模态可知,高原整层大气可降水量的空间分布为全区一致型、东西分布型和南北分布型.

Based on the reanalysis data provided by ERA-Interim,this paper calculates the precipitable water vapor（PWV）over Qinghai-Tibetan plateau and analyzes its spatial distribution,climate tendency rate,and interannual and annual variation characteristics by layers.The results show that the center position and regional difference of spatial distribution and its climate tendency rate at different layers are not the same,and there are obvious seasonal differences.Through inspection,the year of 1995 is found to be the abrupt change year.The annual average and spring,summer and autumn values of PWV are higher before the abrupt change than after it.However,in winter,the value of PWV before the abrupt change is higher than that after it.Before the abrupt change year,annual average and seasonal average of PWV show a rising trend,and after the abrupt change,all the seasons show an upward trend except winter,in which a downward trend is recorded.The rising trend rate is greater before the abrupt change than after it.It can be known from EOF（empirical orthogonal function）analysis of the first three modes that the spatial distribution of PWV over Qinghai-Tibetan plateau has three patterns,i.e.the consistent positive or opposite pattern,and two spatially-opposite patterns：east-west distribution and north-south distribution.