青藏高原东部与其北侧热力差异与高原季风及长江流域夏季降水的关系  

The relationship of the thermal contrast between the eastern Tibetan Plateau and its northern side with the plateau monsoon and the precipitation in the Yangtze river basin in summer

作　　者：岑思弦[1] 巩远发[2] 赖欣[2] 齐冬梅[1] 

机构地区：[1]中国气象局成都高原气象研究所,成都610072 [2]成都信息工程学院大气科学学院 高原大气与环境四川省重点实验室,成都610225

出　　处：《气象学报》2014年第2期256-265,共10页Acta Meteorologica Sinica

基　　金：国家自然科学基金资助项目(41275080;41290255);公益性行业(气象)科研专项(GYHY201006023);高原大气与环境四川省重点实验室开放课题(PAEKL2010-C3;PAEKL-2013-C4)

摘　　要：利用1961—2011年NCEP/NCAR逐月再分析资料及中国584个地面观测站的逐日降水资料,分析了夏季青藏高原及其附近地区大气热源对青藏高原夏季风及中国夏季降水的影响。结果表明,夏季青藏高原主体东部与其以北地区存在明显的热力差异,对青藏高原夏季风有显著的影响,由此定义了一个青藏高原东部与其北侧热力差异指数。当青藏高原东部与其北侧热力差异指数偏大时,青藏高原夏季风偏强,长江流域的夏季降水偏多;反之,当指数偏小时,青藏高原季风偏弱,长江流域的夏季降水偏少;进一步研究发现,当指数偏大时,南北气流在长江流域辐合,使得来自太平洋上的暖湿水汽与来自高纬度地区的干冷空气在长江流域汇合,增大了该地区的水汽含量,同时由于辐合上升运动加强,导致长江流域降水偏多;当指数偏小时,长江流域上空低层西南风增强,来自印度洋与太平洋上的暖湿水汽更多地往华北地区输送,长江流域的水汽含量减少,而该地区的辐合上升运动也明显减弱,降水随之减少。Using the NCEP/NCAR reanalysis data and observed daily rainfall from the 584 gauge stations from 1961 -2011, the relationship between the atmospheric heat source （hereafter called 〈Q1 〉）over the Tibetan Plateau and its surrounding areas and the plateau monsoon and the precipitation in China in the summer has been studied in this paper.The results show that there exists a distinct thermal contrast between the eastern Tibetan Plateau main area and the area north of it and the thermal contrast has significant influence over the plateau monsoon,so we defined an index to reflect the thermal contrast.When the in-dex is high,the plateau monsoon is strong,and the precipitation is more in the Yangtze river basin,and vice versa.In the fur-ther study,when the index is high,the flows from the north and the south convergence over the Yangtze river basin,leading the warm vapor from the Pacific Ocean and the cold air from the high latitude to convergencing therein,and thus to increasing the water vapor content in this region.At the same time,the convergence and ascending motions strengthen,resulting in more rainfall in the Yangtze river basin;when the index is low,the southwesterly winds over the low-level in the Yangtze river basin strengthen,the more warm vapor from the India Ocean and the Pacific Ocean are transported to northern China,and the water vapor content over the Yangtze river basin is decreased,with the convergence and ascent weakened in this region,leading the precipitation in this region to becoming less.

关 键 词：青藏高原 大气热源 长江流域 高原季风 

分 类 号：P461[天文地球—大气科学及气象学]