一次梅雨锋暴雨过程中多尺度能量相互作用的研究Ⅰ.理论分析

The Study of Multi-scale Energy Interactions during a Meiyu Front Rainstorm. Part Ⅰ: Theoretical Analysis

本文是讨论梅雨锋暴雨过程中多尺度能量相互作用问题的开始部分。为了分析梅雨锋暴雨过程中的多尺度能量相互作用,从z坐标系中的运动方程和热力学方程出发,把基本物理量分成大尺度背景场(>2000 km)、α中尺度(200~2000 km)和β中小尺度系统(<200 km)分量,利用滞弹性近似,推导了大尺度背景场、α中尺度和β中小尺度系统三个尺度的动能方程和位能方程。能量方程中包含了各尺度动能之间的转换、位能之间的转换以及动能和位能之间的转换。动能方程主要包括各尺度动能之间转换项、动能输送项、水平气压梯度力做功项、垂直方向扰动气压梯度力做功项、浮力做功项、地转偏向力分量做功项以及摩擦力做功项。位能方程主要包括各尺度位能之间转换项、位能输送项、浮力做功项以及非绝热加热做功项。其中浮力做功项为位能和动能之间的能量转换项,是暴雨发生发展过程中比较关键的能量转换项。关于将能量方程用于梅雨锋暴雨过程中并且诊断能量相互作用影响暴雨发展和消亡过程的物理机制等问题,将在以后的研究中给出。

This paper is the beginning part of the discussion on the multi-scale energy interactions in the Meiyu front rainstorm. The kinetic energy equations and potential energy equations of large scale background field, meso-α scale and meso-micro-β scale are derived from motion equations and thermodynamic equations in the z coordinate system using the anelastic approximation by dividing the basic physical quantity into three scales for the purpose to analyze the multi-scale energy interactions. Various energy conversions are presented in the energy equations. The kinetic energy equations mainly include kinetic energy transportation or conversion, the work of horizontal pressure gradient force, vertical perturbation pressure gradient force, buoyancy, Coriolis force and friction. The potential energy equations mainly include potential energy transportation or conversion, and the effects of buoyancy and diabetic heating. Among them, the effect of buoyancy is substantially the energy conversion term between the potential energy and kinetic energy, and thus is the most critical energy conversion term in the process of rainstorm development. In the future study, the energy equations will be applied to the Meiyu front rainstorm, and the physical mechanism for the diagnosed energy interaction, which affects the development and disappearance of rainstorm, will be given.