青藏高原上空夏季水汽含量的时空分布特征

Spatial Distribution of Water Vapor Content over the Qinghai-Tibet Plateau in Summer

利用青藏高原地区1979-2008年14个探空站的观测资料以及同期的NCEP/NCAR再分析资料,采用线性趋势、Mann-Kendall突变检验和合成方法,分析高原上空夏季水汽含量的时空演变特征及影响高原水汽含量异常的大气环流等因子。结果表明:高原夏季水汽含量在空间上表现出随海拔高度升高而减少的分布特征,即高原东南部和东北部湿润,西北部干燥。近30 a来,高原夏季水汽含量整体上呈现出增加趋势,其中高海拔的西部干燥地区水汽含量的增加较东部湿润地区更加显著。高原夏季水汽含量偏多(少)年,高原地区整层水汽通量以辐合(散)为主,高原上空低层的位势高度以负(正)距平为主,高原地表温度整体上偏高(低)。

Based on the sounding data from 14 sounding stations over the Qinghai-Tibet Plateau during the period of 1979 -2008 and the NCEP/NCAR reanalysis data in recent 30 years, the spatiotemporal distribution of water vapor content over the plateau in summer and the factors affecting abnormal water vapor content were analyzed using the means of linear trend method, Mann-Kendall test and composite analysis. The results show that water vapor content over the plateau in summer was decreased with the increase of altitude, namely water vapor content was high over the southeastern and northeastern parts of the plateau but low over the northwest part ; On the whole, water vapor content over the plateau in summer was in an increase trend in recent 30 years, especially over the arid western region. The characteristics of the years with high （ or low） water vapor content over the plateau in summer were as follows： （1） Water vapor flux was converged （or diverged） in the years with high （or low） water vapor content ; （2） The potential height of water vapor content over the low-level plateau was in a negative （ or positive） anomaly in the years with high （or low） water vapor content; （3） Surface temperature was higher （or lower） in the years with high （or low） water vapor content.