暖性西南低涡生成的一种可能机制

A POTENTIAL MECHANISM OF THE WARM VORTEX GENESIS IN SOUTHWEST CHINA

本文根据非绝热、有摩擦情况下的热成风适应原理,探讨暖性西南低涡生成的机制,并对两次暖性西南低涡过程进行分析。结果表明:暖性西南低涡生成前12小时,在低涡源地附近存在较大的正值非热成风涡度,地面感热加热和暖平流对于产生正值非热成风涡度有重要贡献。由于西南低涡在生成初期为一浅薄系统,v 值较大时,L>L_0的条件可以满足,适应的结果在低层形成暖性西南低涡。

According to the thermal wind adjustment theory under non-adiabatic and frictional effects,the genesis mechanism of the warm low vortex in southwest China is discussed in this paper,andtwo cases are analysed and calculated.The results show that there is an obvious area of positivenon-thermal wind vorticity in the vicinity of vortex source 12 hours before the vortex formation.The surface sensible heat and warm advection play an important role in the generation of positivenon-thermal wind vorticity.Because the warm low vortex is a shallow system in the initial stage,the condition L>L。may be satisfied when the lapse rate of temperature is larger.Therefore,theeffect of thermal wind adjustment can make the warm low vortex generated in the lower layer.