STUDY ON THE VORTEX OF THE QINGHAI-XIZANG (TIBET) PLATEAU IN SUMMER

In this paper an ideal model for the formation and development of the Qinghai-Xizang Plateau vortex is presented by a large number of statis tical data and typical case studies. It points out that the Plateau vo rtex is shallow and thermal originated from a strong heat source near the surface of the west of the Plateau. Then moving eastward, it devel ops and becomes stronger and thicker with larger upward vertical veloc ity, and causes great precipitation in the middle Plateau. But at this time the heat source in the vortex becomes weaker, and even the heat sink occurs near the surface. Consequently, it disappears in a cold tr ough with a strong heat sink in the east of the Plateau. The heat sour ce (sink) is mainly determined by the vertical eddy flux convergence ( divergence) of the sensible heat caused by the cumulus convection and turbulance. Both the nonuniform heating (cooling) at the surface and t he convergence (divergence) of the eddy kinetic energy coact and play an important role in the genesis (disappearance) of the Plateau vortex in the west (east) Plateau. The transformation value from the mean ki netic energy to the eddy kinetic energy increases when the Plateau vor tex moves eastward, helping the formation of the cold trough and the i ncrease in + zeta and large-scale precipitation in the east Plateau.