一个简单的准地转海气耦合模式

文章采用准地转带耗散因子的大气和海洋的动量、热力学方程,建立了一个简单的描写大尺度运动的准地转海气耦台浅水模式,分别在中高纬和低纬地区讨论了海气的耦合效应,分析了耦合低频模(海洋模)的振荡周期随耦合频率和经向波数的变化转征,并由此而说明低频振荡与海气相互作用有关。然后从海洋和大气的频散曲线中揭示出耦合强度对Rossby波传播的影响,还从缓变波列的观点,讨论了两种模之间的转换机制。 结果表明:Newton冷却Rayleigh摩擦对海洋Rossby波起稳定作用。随着耦合频率的增加,耦合低频模的周期也相应增加;经向波数越大,这种增加就越迅速。当耦合频率趋近于临界值时,海洋Rossby波趋于静止。当海气耦合强度增加到一定程度时,海洋Rossby波的传播方向变成与原来相反。通过海气相互作用,海洋Rossby波的一部分将转换成大气Rossby波,本文求解了其能量转换系数。 

A SIMPLE QUASI-GEOSTROPHIC COUPLED OCEAN-ATMOSPHERE MODEL

The quasi-geostrophic atmospheric and oceanic equations of momentum and thermodynamics with dissipation factors are used to create a simple coupled ocean-atmosphere model describing the large scale shallow water motion. The ocean-atmosphere coupling effects are discussed separately for mid-high and low latitueds and variational characteristics are analyzed of oscillatory periods and coupled low-frequency modes (oceanic) against the coupled frequency and latitudinal number, on the basis of which the low-frequency oscillation is shown to be related to ocean-atmospere interactions. Then, from the dispersion curves of atmosphere and ocean, effects of the coupling strength on the propagation of Rossby waves are revealed. The conversion mechanism between the two modes is also discussed as viewed from the wave train that varies slowly.The results show that Newtonian cooling and Rayleigh friction stabilize oceanic Rossby waves and with growing coupled frequency, the period of coupled low-frequency mode increases and more rapidly so with .greater latitudinal number. When the coupling frequency approaches to a critical value, the oceanic Rossby Waves tend to be static. As the ocean-atmosphere coupling strength grows to some degree, the propagation of oceanic Rossby waves will reverse to its own opposite direction. One part of the oceanic Rossby waves is converted into atmospheric Rossby waves and the energy conversion coefficitnt is also derived in this paper.