关键词: 中尺度运动, 半平衡模式, 准平衡模式

Abstract: The physical characteristics of mesoscale are analyzed, and results show that the unbalanced forced motion is the fundamental cause, which lead to evolution of some important mesoscale weather systems. The mesoscale dynamics equations are the basis of the theoretical studies of mesoscale atmospheric dynamics. There fore, according to the characteristics of the mesoscale motion, the formal scaling analysis and the asymptotic theory are used to simplify the governing atmospheric dynamics equations which are based on fluid dynamics and thermodynamics, so they can describe the basic characteristics of the mesoscale motion more accurately. These procedures are essential for the development of the mesoscale dynamics. The semi-balanced and quasi-balanced models based on nonlinear balance equation are derived;they are in analogy with the semi-geostrophic and quasi-geostrophic models, respectively, and may be used as basis for the theoretical studies of the mesoscale atmospheric dynamics. The uasi-balanced model is also used to study the mesoscale balanced vortex system, and the conclusion has shown that the mesoscale vortex system is mainly controlled by the gradient wind, and the development of its wind and pressure fields are described by an evolution equation.

Key words: mesoscale, semi-balanced model, quasi-balanced model