The Dynamic Effect of the Qinghai-Xizang Plateau on the Formation of Low Level Jet in East Asia

Abstract

Low-level jet, due to its close relationship with severe weather in summer, attracts broadly the interest and attention of meteorologists. In recent years a large number of researches have been done to the structure and characteristics of jets, the mechanism responsible for their formation and their roles in the formation of severe convective weather. Large-scale low-level jets, whether in East Asia or in the great plain of North America or East Africa, are located east of mountains or high lands and facing the oceans. This fact suggests that this particular geographic location might contribute to the formation of jets. An explanation has been given by Wexler [1] to the southly low-level jets over the mid-west of America which is located in the east of the Rockies. It is therefore suggested that there is a theory, which might be considered as an extension or modified version of the theory for oceanic current at the west boundary of the ocean, that the southly jets to the east of the Rockies are but the result from the interaction of the easterly from Bermuda high pressure with the N-S oriented mountain barrier. The same theory has been used to explain the low-level jet over East Africa. The works of Hahn and, Manabe[2] and Washington et al.[3] show that when the mountains are removed from the model the cross-equatorial flows diverge and become rather weak. When the highland is included, a jet with a scale similar to reality appears.