正压大气中尺度半平衡和准平衡动力学模式

应用描写正压大气运动的基本方程组，分析了中尺度大气运动的物理特征，指出非平衡强迫运动是引起中尺度重要天气演变的根本原因。中尺度动力学方程组是中尺度动力学理论研究的基础，因此，结合中尺度大气运动的基本特征，依据严格的尺度分析理论和摄动理论，简化基于流体力学和热力学的大气动力学方程组使之能够恰当地描述出中尺度运动的基本特征，对于中尺度动力学的发展是极为必要的。基于非线性平衡方程所得到的半平衡和准平衡动力学模式分别与半地转和准地转模式极为相似，它们可以较精确地描述中尺度大气运动的基本特征，因而，可作为中尺度动力学研究的理论基础。将准平衡动力学模式应用于中尺度涡旋系统的研究，结论表明中尺度平衡涡旋系统主要是受梯度风控制，其流场和气压场的发展演变则由一个演化方程来描写，获得了较为理想的结果。

Barotropic Mesoscale Semi-Balanced and Quasi-Balanced Dynamic Models

The physical characteristics of mesoscale are analyzed, and results show that the unbalanced forced motion is the fundamental cause of the evolutions of some important mesoscale weather systems. The mesoscale dynamics equations are the basis of the theoretical studies of mesoscale atmospheric dynamics. Therefore, according to the characteristics of the mesoscale motion, the formal scaling analysis and the asymptotic theory are used to simplify the governing atmospheric dynamical equations, which are based on fluid dynamics and thermodynamics. Therefore they can describe the basic characteristics of the mesoscale motion more accurately, which is essential for the development of the mesoscale dynamics. In this paper, the semi-balanced and quasi-balanced models based on the nonlinear balance equation are derived; they are in analogy with the semi-geostrophic and quasi-geostrophic models, respectively. Both models can describe the basic characteristics of the mesoscale motion and may be used as bases for the theoretical studies of the mesoscale atmospheric dynamics. The quasi-balanced model is also used to study the mesoscale balanced vortex system, and the conclusion shows 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 evolutional equation.