Numerical Study of Influence of the Qinghai-Xizang Plateau on the Late Spring Cold Spell Event South of the Changjiang River

By employing the improved T42L5 spectral model and utilizing the ECMWF data of 12 UTC 25 March 1985 as the initial field, a numerical study of the effect of the Qinghai-Xizang Plateau on the formation of the cold spell in the late spring south of the Changjiang River has been made. The results show that the dynamic effect of the Plateau can help the cold air move along the east of the Plateau from the north to south and the south trough with generation and maintenance on the southeast side of the Plateau. Due to the dynamic effect of the lee wave east of the Plateau, sough trough becomes deeper and moves towards the east, with the result that the low temperature process can remain in the south of the lower reaches of the Changjiang River.