SIMULATION STUDY OF THE EFFECT ON COLD SURGE OF THE QINGHAI-XIZANG PLATEAU AS A HUGE OROGRAPHY

Using a limited-area P-σ incorporated coordinate five-level primitive equation model fed with theECMWF 5°×5°grid data,a simulation is made of a large-scale cold surge of late December 1982.Resultsshow that the Qinghai-Xizang Plateau has no profound thermal but dynamic effect on the East-Asian wintermonsoon that forces cold air to go southwards by its east side,exciting Kelvin waves behind the cold frontto result in the maximum NE wind.Besides,gravitational waves independent of the Plateau occur aheadof the front advancing towards the south.They may be due to the excitation involved in the front itself.The cold surge is propagated under the Hadley cell,making it strengthened and moved southwards.