夏季青藏高原加热和北半球环流年际变化的相关分析

INTERANNUAL VARIATION OF THE DIABATIC HEATING OVER THE TIBETAN PLATEAN AND THE NORTHERN HEMISPHERIC CIRCULATION IN SUMMER

利用 195 8～ 1997年NCEP/NCAR再分析数据集中加热率和环流资料 ,采用相关分析和对比分析相结合的方法 ,诊断和分析了夏季青藏高原的非绝热加热与北半球环流系统的年际变化的联系。分析结果表明 :夏季青藏高原的加热强 (弱 )的年份 ,高原及邻近地区的上升运动、下层辐合及上层辐散均增强 (减弱 ) ,使高原加热对周边地区低层暖湿空气的抽吸效应和对高层大气向周边地区的排放作用加强 (减弱 )。从而影响着高原和周边地区的环流以及亚洲季风区大尺度环流系统。而且高原的加热强迫能够激发产生一支沿亚欧大陆东部海岸向东北方向传播的Rossby波列 。

The diabatic heating rates and circulation data from NCEP/NCAR reanalysis (1958-1997) are employed to study the interannual variation of the summertime diabatic heating over the Tibetan Plateau (TP) and the Northern Hemispheric circulation, and the relationship between them by using correlation and composite methods. It is shown that when the summertime diabatic heating over the TP is stronger than normal, the rising motion as well as low level convergence and upper level divergence of the air over the TP and the neighboring areas is intensified. This will induce the stronger than normal sucking in of the low level warm and moist air towards the TP, and more intense pushing out of upper level air as well. The atmospheric circulation over the TP and the Asian monsoon area is therefore affected. Besides, a Rossby wave train is forced by the diabatic heating over the TP and by the induced divergence field along the eastern coast of Asia, propagating northeastward and affecting the circulation in the Northern Hemisphere.