黄河流域水汽的区域分布及演变特征

Distribution and evolution characteristics of water vapor over the Yellow River basin

利用1948-2009年NCEP/NCAR再分析资料,研究了黄河流域年平均、1、4、7、10月整层水汽含量的时空分布特征。结果表明:年平均水汽含量为5～27mm,时间上,冬季(1月)和夏季(7月)分别为最低和最高,空间上,青藏高原和黄河下游上空分别为最低和最高,西风带水汽大小居于两者之间;利用旋转经验正交函数(rotated empirical orthogonal function,REOF)展开方法,将黄河流域年平均水汽含量划分为2个区,1、4、7、10月均划分为4个区;年平均及各月全流域和黄河中下游区水汽含量均趋于减少,其余各分区演变趋势各异。

Based on the NCEP/NCAR reanalysis data from 1948 to 2009,this paper studies the spatial and temporal characteristics of vertically integrated water vapor content of annual average,January,April,July and October over the Yellow River basin.Results show that the annual average water vapor content is 5—27 mm.The water vapor content reaches the minimum in winter（January） and the maximum in summer（July）,and it is the lowest over the Tibetan Plateau and the highest over the lower Yellow River,while it is in the middle over the westerly belt.By means of REOF（rotated empirical orthogonal function） method,the atmospheric precipitable water of annual average,January,April,July and October can be divided into two,four,four,four and four sub-regions over the Yellow River basin,respectively.The water vapor content over the whole basin and the middle and lower Yellow River basin tends to decrease,while the trends are different over other subareas.