青藏高原及附近水汽输送对其夏季降水影响的分析

Water Vapor Transportation and Its Influences on Precipitation in Summer over Qinghai-Xizang Plateau and Its Surroundings

利用欧洲中期天气预报中心(ECMWF)提供的1979-2010年ERA-Interim再分析资料分析了青藏高原(下称高原)及附近夏季水汽输送通量分布情况,并结合基于迄今为止最全面的地面观测数据形成的高分辨率降水资料分析出4条影响夏季高原降水的水汽通道:西风带、阿拉伯海、孟加拉湾北部及南海通道。结果表明:高原夏季降水量高值年(1979、1984、1996、1998、2002、2004、2007年)、低值年(1994、2001、2006年)与孟加拉湾北部通道水汽输送强弱年有较好对应。夏季西风带通道的影响较弱,与其他3条低纬度通道的相关系数较小,是相对独立的水汽通道,主要影响高原西北部从狮泉河至塔里木盆地南侧地区;孟加拉湾北部通道影响高原中南偏东部地区;南海通道则对高原东南部以及中南部那曲、林芝、昌都、玉树等地区有影响;而阿拉伯海水汽通道与其他水汽通道都呈负相关关系,其中与孟加拉湾北部通道相关关系最显著,相关系数达到-0.65,该通道通过调节孟加拉湾北部通道和南海通道的向西水汽输送分量来影响高原中南偏西部地区的夏季降水。

Based on the European Centre for Medium-Range Weather Forecasts（ECMWF）Interim Reanalysis（ERA-Interim hereafter）from 1979 to 2010,the average water vapor transport flux distribution in summer over the Qinghai-Xizang Plateau（QXP hereafter）is calculated and studied. Combined with the high resolution observational data of the daily precipitation over the QXP,four moisture paths influencing the precipitation over the QXP are found,which are defined as the paths of westerly,Arabian Sea,the northern side of Bay of Bengal and South China Sea,respectively. Moreover,the area and function of these paths influencing precipitation process over the QXP have been analyzed and addressed. The results show that the years of both strong（1979,1984,1996,1998,2002,2004,2007）and weak（1994,2001,2006）precipitation over the QXP are consistent with the results reflected from path of the northern side of Bay of Bengal. Compared with the rest paths,the influence of the westerly path is weakest,which only has an role in the northwest QXP from Shiquanhe to the south of Tarim Basin; The northern side of Bay of Bengal path has an effect in the central-southeastern QXP;the path of the South China Sea dominates the southeastern and central- south of QXP such as Naqu,Linzhi,Changdu,Yushu and other regions; Arabian Sea path has negative correlations with the rest three paths,especially with the northern side of Bay of Bengal path（R=-0. 65,P0. 05）. Furthermore,Arabian Sea path indirectly modulates the central- southwestern QXP by adjusting the intensity of both the northern side of Bay of Bengal path and South China Sea path. These results suggest that both the water vapor transport path and pattern of precipitation over the QXP is coherently connected.