中国西南纵向岭谷地区可降水量的变化特征

利用NCEP/NCAR 1948~2002年月平均比湿、风场以及高度场等再分析资料,对纵向岭谷及周围地区的多年平均气柱可降水量及其月、季节变化以及年际和年代际变化特征进行了分析。结果表明,纵向岭谷地区可降水量具有明显的月际、季节、年际和年代际变化。在纵向岭谷地区,气柱平均可降水量季节变化明显。四季都为南湿北干的分布,夏季可降水量含量最大,冬季最小,云南大气含水量的分布在整体上大致为西北东南向的"凹"字形。纵向岭谷可降水量的月际变化反映了纵向岭谷地区南北向通道作用和东西向阻隔作用。夏季可降水量在25°N附近、98.5°E附近以及106°E附近地区发生了明显变化。夏季、冬季纵向岭谷区的可降水量变化具有明显的年际和年代际变化特征。纵向岭谷区夏季可降水量在20世纪70年代初发生了年代际变化;冬季可降水量在20世纪50年代中期、60年代后期以及80年代初期发生了年代际变化。

The Variations of Atmospheric Precipitable Water over Longitudinal Range-Gorge Region (LRGR) in Southwestern China

In this paper,the multiyear feature and their monthly,seasonal,yearly and interdecadal changes for the air column precipitable water(hereafter PW) over Longitudinal Range-Gorge Region and its surroundings have been analyzed,utilizing the NCEP’s monthly mean specific humidity,wind velocity and potential height reanalyzed grid data and the observed rainfall data.The results show that there exist the considerably monthly,seasonal,yearly and interdecadal changes of the air column PW over the LRGR.It is wetter in the south than that in the north.There are maximum PW in summer and the minimum PW in winter.The air column PW over Yunnan presents approximately a southeast-northwestern U-shaped pattern.The monthly variations of PW show the"corridor-barrier"effect of LRGR.Summer PW shows distinct changes over 25°N, 98.5°E and 106°E.The variation of the summer and winter PW in LRGR is characteristic by both interannual and interdecadal scale.Summer PW underwent a catastrophe in the early 1970s; winter PW underwent a catastrophe in the mid 1950s, the late 1960s and the early 1980s.