摘要
本文设计—关于基本气流线性化的二层球面模式研究大气对不同类型赤道热源的低频响应,分析了全球大气40—50天低频振荡的结构和传播特点。结果表明:全球大气对热带热源响应特征是在热带地区表现为东西向非对称的热源东侧的Kelvin响应和西侧的Rossby响应,高低层反位相;在中高纬响应是具有低频振荡的二维Rossby波列,且具有相当正压结构。低频振荡的传播特征表明热带大气对移动性热源的响应更有利于振荡的向东传播,且该振荡可以沿波列路径向中高纬度传播,然后再折向低纬。二维Rossby波列是联系着热带和中高纬度地区低频振荡的基本动力学途径。该波列的形成取决于基本气流的分布,冬半球波列振幅较大。因此本文认为40—50天低频振荡是全球尺度的现象,它是一涉及到热带对流加热、赤道Kelvin波、亦道Rossby波、二维Rossby波列以及基本气流等动力学相互作用的过程。
A two layers spheric model linearized about basic flow has been designed to study the low-frequency response of atmosphere to three kinds of the equatorial heat, especially to study features of the structure and propagation of 40-50 day oscillations of the global scale. Results show that the structure of the low-frequency response to three kinds of the equatorial heat in the tropics is mainly characterized by the east-west asymetry with kelvin (Rossby) response to the east (west) of the heat source and by the reverse phase variation between the high and low levels. The structure in Ihe middle and high latitudes is characterized by the two dimensional Rossby wavetrains response which is equivalent baro-tropic. The wavetrain is stronger in winter Hemisphere. In the tropics, only to the moving heat source can response of the zonal wind propagate eastward, and in this case response exists fixed nodes and antinodes. In the extratropics, the ohase propagates mainly along the two dimensional Rossby wavetrain route which indicates the interaction of the 40-50 day low-frequency oscillation between the tropics and the extra tropics. It is also shown, that this interaction of oscillation in different latitudes is determined by the distribution of the basic flow.Finally. it is suggested that 40-50 day oscillation of the global scale is a dynamical process of interaction associated with the tropical convection, the equatorial Kelvin and Rossby waves, the two dimensional Rossby wavetrains in the middle and high latitudes and the basic flow.
出处
《气象科学》
CSCD
北大核心
1990年第4期384-393,共10页
Journal of the Meteorological Sciences
