风的垂直切变对滞弹性大气中静力适应过程的影响  

The effect of wind vertical shear on the hydrostatic adjustment process in the anelastic atmosphere

作　　者：郭海龙 刘宇迪 

机构地区：[1]国防科学技术大学气象海洋学院,南京211101

出　　处：《地球物理学报》2018年第1期65-79,共15页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41175089)资助

摘　　要：本文基于描写滞弹性大气静力适应过程的线性方程组,从波动频散关系、气团运动规律和能量转换的角度出发,研究了水平基流及其垂直切变对该模式大气静力适应过程的影响.构造四种水平基流垂直分布模型进行比较,分别为常数型、线性切变型、反气旋切变型和气旋切变型,得到结论:(1)具有重力波性质的波动是滞弹性大气静力适应过程中扰动能量传播的方式,当垂直折射指数大于零时,基本气流及其垂直切变的存在,不仅改变了波动频率的大小,而且改变波动传播的方向;(2)在静力适应过程中气块的运动轨迹呈椭圆形,水平基流及其垂直切变影响椭圆的扁率,同时也影响扰动物理量之间的偏振关系;(3)水平基流的垂直切变是扰动能量和水平基流能量发生转换的媒介,当存在垂直向上的动量输送时,正的垂直风切变对应扰动能量的衰减,水平基流能量的增加,负的垂直风切变对应扰动能量的增加,水平基流能量的衰减;(4)不同的风的垂直切变模型,对静力适应过程的影响不同;对于水平基流呈反气旋切变型和气旋切变型,扰动发展的波动垂直结构为,急流轴上方波动等相位线自下而上向西倾斜,急流轴下方波动等相位线自下而上向东倾斜,反之亦然.The influence of vertical wind shear （WVS） on the hydrostatic adjustment process in the atmosphere is investigated by using the normal modes method based on the linear equations describing the dynamics and thermodynamics of a compressible atmosphere on the anelastic approximation. Four WVS models of the horizontal basic flow are considered：the constant model, linearly shear model, cyclonic shear model and the anti-cyclonic shear model. The different effects of the four WVS models are compared from the perspective of dispersion relationship, group velocity, and phase velocity and energy conversion, respectively. The results show that （1） the frequency dispersion of disturbed energy in the anelastic model has the properties of gravity waves.When the vertical refraction index is greater than zero, the presence of WVS changes the magnitude of the wave frequency.At the same time, it changes the direction of wave propagation. （2） The motion regular pattern of parcels accord with the elliptic equations.The WVS affects the oblateness of the elliptic equation and the polarization of perturbation physical quantities. （3） The WVS serves as a medium for the conversion of the energy between the perturbation field and basic flow field. In the case of vertical momentum flux upward transportation, the positive WVS causes the attenuation of the perturbation energy and the growth of energy stored in the basic flow field.On the contrary, the negative WVS causes the growth of the perturbation energy and the attenuation of energy stored in the basic flow field. （4） The impacts on the hydrostatic adjustment caused by these four WVS models have great differences. If the vertical structure of the wave is present in this configuration, at the top of the jet stream, the phase contour line is tilted toward the west from the bottom to the top; and below the jet stream, the phase contour is tilted toward the east from the bottom to the top; and vice versa.

关 键 词：风的垂直切变 滞弹性大气 静力适应 能量转换 

分 类 号：P433[天文地球—大气科学及气象学]