摘要
本文应用Ertel位势涡度的理论,分析了两例夏季江准气旋活动的等熵面位涡图和位涡垂直廓线,讨论了这类系统发生发展的一种可能机制以及它们与典型温带气旋的区别,从而得出了夏季江淮气旋活动的一个概念模式:从高原一带东移的对流层中层弱的扰动在有利条件下引起江淮地区较强降水,中层潜热释放导致气旋性环流向下延伸,最终可在地面静止锋上形成波动。当副热带锋区北侧平流层下部空气沿等熵面南下时,气旋波可能发展成为典型的温带气旋。
Based on the theory of Ertel potential vorticity, the isentropic potential vorticity maps and vertical potential vorticity profiles for two summer depressions over the Changjiang-Huaihe Valley are analysed. After discussing a possible mechanism for the genesis and development of such systems and their difference from typical extratropical cyclones, a conceptual model for their activities is proposed: A mid-level, weak disturbance originated from around the Qinghai-Tibet Plateau may cause heavy precipitation under favourable conditions, latent heat release in the mid-troposphere leads to downward extension of cyclonic circulation and a wave on the quasi-stationary front. This weak cyclone can develop substantially and become a typical extratropical cyclone only when air from the lower stratosphere flows downslope along isentropic surfaces into the region of interest.
出处
《气象学报》
CSCD
北大核心
1991年第2期141-150,共10页
Acta Meteorologica Sinica
