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

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 heat ing 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.