青藏高原及周围地区大气可降水量的分布、变化与各地多变的降水气候

为了更深入地分析青藏高原及邻近各地多变的降水气候，利用NCEP 1958—1997年月平均比湿、风及高度等再分析资料及我国实测雨量资料等，整体地分析了高原及周围地区气柱可降水量的多年平均特征及其季节变化，也分析了我国南北方大气可降水量的年代际变化和华北及西北区东部干湿年夏季可降水量的差异等。结果表明，高原及周围地区的气柱可降水量有明显的地区及季节变化。本区域内以南亚和东亚夏季风区的可降水量最高，夏季可达60mm或以上；青藏高原上的可降水量最低，冬季为3mm左右。东亚和南亚季风区可降水量的冬夏季节变化最大，夏季的可降水量达冬季值的4倍。华北区干湿夏季的可降水量差异明显，湿年的可降水量可增加20％以上。近40年来华北和西北区东部夏季的气柱可降水量明显减少，而长江流域及江南地区20世纪80年代以来可降水量却部分增加了，呈北干南湿之势，遂形成我国降水北旱南涝的分布格局。这可能与东亚夏季风逐渐趋弱，特别是撤退期逐渐提前有关。另外，我国各地夏季可降水量的平均降水转化率也明显不同，青藏高原上最高，东亚季风区次之，而南疆盆地最低，这也影响了我国多变的降水气候。

Distribution,Changes of Atmospheric Precipitable Water over Qinghai-Xizang Plateau and Its Surroundings and Their Changeable Precipitation Climate

In this paper, the multiyear mean features and their seasonal, yearly and interdecadal changes for the air column precipitable water (hereafter PW) over the Qinghai-Xizang Plateau and its Surroundings (QXPS) have, wholly, not partly, been analyzed, utilizing the NCEP's monthly mean specific humidity, wind velocity and potential height reanalyzed gridded data and the observed rainfall data etc. The results show that there exist the considerably regional, seasonal, yearly and interdecadal changes of the air column PW over the QXPS. Over the QXPS there are the maximum PW over the South and East Asian Monsoon regions, with the value of 60mm or more in summer; the minimum PW over the Qinghai-Xizang Plateau (QXP), with only 3mm in winter. In East and South Asian Monsoon areas have the largest summer and winter seasonal changes of the PW, the PW values summer are four times as large as those winter. In recent four decades the air column PW over the North China and east part of Northwest China are continually being decreased; but has something increase tendency over the Changjiang river reaches and to the south of it since 1980's, namely with the distribution pattern of drying in the north and wetting in the south in China. On the other hand, there are the striking differences in the PW conversion rate into precipitation in various parts of China summer, with the highest rate in QXP, the second highest in East Asian Monsoon areas, the minimum one in south Xinjiang.