夏季青藏高原空中云水资源的时空特征分析

Temporal and Spatial Characteristics of Water Vapor and Cloud Water over the Qinghai-Xizang Plateau in Summer

为了揭示青藏高原空中云水资源的分布状况,利用ERA-Interim月平均再分析资料和EOF分解、相关分析等方法对1979-2016年夏季高原空中云水资源的时空演变特征进行了研究。研究表明:(1)夏季高原整层水汽含量变化范围为2~25 kg·m-2,呈东南向西北递减;1979-2016年高原地区水汽含量变化呈增加趋势。(2)夏季高原整层水汽通量均为正值,水汽输送主要以向东输送为主;高原大部分地区为弱水汽辐合区,净获得水汽;除南边界外,其余边界及周边地区为水汽辐散区,净失去水汽。(3)整层云水含量分布大值区主要在喜马拉雅南翼和高原东南部地区,高原区域的整层云水含量以1.9 g·m-2·(10a)-1以上的速率增加。(4)1979-2016年夏季高原区域平均的整层水汽含量随时间增加,增加率为0.3 kg·m^-2·(10a)^-1;南北向水汽收入呈增加趋势,东西向水汽收入呈减少趋势,从而高原区域水汽净收入变化趋势不明显。

In order to reveal the distribution of water vapor and cloud water in summer over the Qinghai-Xizang Plateau,based on the ERA-Interim monthly reanalysis data from ECMWF the temporal and spatial characteristics of total column water vapor,water vapor flux and total column cloud water over the plateau in summer from1979 to 2016 were studied by EOF analysis and correlation analysis methods. The main conclusions are as follows:(1)The variation range of total column water vapor over the plateau in summer is 2~25 kg·m-2. It decreases from the southeast of the plateau to the northwest. Its variation trend increases in summer from 1979 to 2016.(2)The total column water vapor flux over the plateau is positive in summer during 1979-2016. And the water vapor is mainly transported eastward. The most areas of the plateau are the weak convergence areas of the water vapor with net water vapor obtained. Except for the south boundary of the plateau,the rest surrounding areas are the divergence areas of water vapor with net water vapor lost.(3)The distribution of the maximum value of total column cloud water is mainly in the south wing of Himalayas and the southeast of the plateau. The total column cloud water over the plateau increases with the rate of 1. 9 g·m-2·(10 a)-1 in summer.(4)During the summer of 1979-2016,the averaged total column water vapor over the plateau increases with the rate of 0. 3 kg·m-2·(10 a)-1;The meridional net water vapor budget increases,while the zonal one decrease,so the trend of the regional net water budget is not obvious.