ON THE DYNAMICS OF SUBTROPICAL UPPER-TROPOSPHERIC QUASI-STATIONARY VORTICES IN NORTHERN SUMMER

In this paper the dynamic mechanism of the subtropical quasi-stationary vortices in the upper troposphere,such as the southern Asia high and the mid-oceanic troughs,are studied with a highly truncated spectral model,in which the thermal forcing and the nonlinear interaction between wave and zonal components,as well as the basic zonal flow changing with latitudes are incorporated.The results show a stable equilibrium statewith an upper level fiow field similar to the observed subtropical systems.It is found that the thermal forcing has some important controlling effects on these planetary-scale vortices.