频散效应对自由大气能量输送的影响

本文应用扩大的Ｐｒａｎｄｔｌ混合长理论分析自由大气中的Ｒｅｎｏｌｄｓ平均运动方程组，着重分析了频散效应对自由大气大迟度运动能量输送的影响。分析指出：频散效应的自由大气中能量由扰动动能向平均动能转换（即能量逆转）的根本原因；正压大气能量逆转只能在扰动的尺度小于临界迟度Ｌｃ时才能发生；斜压大气能量逆转主要在扰动的厚度小于临界厚度Ｄｃ时发生。不同尺度的扰动与包含和不包含频率散效应的简单模式结果验证了上面

Influence of Dispersion Effects of Transient Eddies on Energy Transport in the Atmosphere

New Renolds' mean momentum equations including both viscosity and dispersion effects of atmospheric transient eddies are deduced by using the modified Prandtl Mixing Length Methods. These equations are used to analyze the dispersion effects of atmospheric transient eddies on the energy transport is the atmosphere. It is pointed out that the dispersion effects of transient eddies in the main reason of energy inversion, which means the energy transported from eddy kinetic energy to mean flow kinetic energy. For the barotropic atmosphere, energy inversion takes place when the eddy scale is less than critical scale Lc. For the baroclinic atmosphere, energy inversion occurs when the horizontal eddy scale is less than critical scale Lc or the eddy thickness is less than critical value DC. Cases of different eddy scale with and without dispersion effects are tested by simple model.