Diagnostic Analysis of Winter Gale Complex Terrain in the Southeast of Qinghai-Xizang Plateau

Abstract

In order to have some physical cognition to the typical gale formation of the southeast complex terrain in Qinghai-Xizang Plateau,five typical gale cases in winter at Dali National Climate Observatory are selected and general analysis is made based on conventional NCEP sounding data,WPR and PBL data.The results show that:(1) The gale cases have similarity circulation background.There are more than one high-pressure system on low latitude near 15°N,long wave and trough of low pressure appears in the high latitudes north of 35°N.(2) The meridional circulation shows vertical movement has the effect on the Dali gale,which mainly presented that vertical movement action of the altitude momentum.(3) Dali gale also has low-level jet background,which transported downwards influence by lower layer velocity rotation.(4) The downward transfer of sensible heat and latent heat provide thermal conditions which make the gale produce and maintain.(5) The WPR probe height and signal-to-noise ratio intensity can be used as one of the gale warning qualitative indicators in Dali.When sensible heat flux and latent heat flux present out of phase to each other,it also can be an indicator to the gale.