强迫耗散非线性系统的局域阻塞流型

LOCAL BLOCKING FLOW PATTERN IN A FORCED AND DISSIPATIVE NONLINEAR SYSTEM

本文将正压涡度方程约化为强迫耗散的KdV方程,求得了该方程的一个定常解.这个定常解描述了非绝热加热、耗散、非线性平流和线性频散共同作用所形成的阻塞流型.在确定性初条件、随机性初条件和随机热源扰动的情况下,积分时间大于60天的三组试验表明:该阻塞流型闭合高压中心位置维持定常,而阻高中心强度的演变显示出清晰的准两周或一个月左右的低频振荡现象.

The barotropic vorticity equation is reduced to a KDV one containing the terms of forcing and dissipation, of which a stationary solution is obtained. It describes a local blocking flow pattern developed under the joint action of nonadiabatic heating, dissipation, nonlinear advection and the linear dispersion. By using the KDV equation, three numerical integrations whose integrative time is longer than 60 model days are performed. The results show that a transient motional form can appear, in which exist low-frequency oscillations of strength of blocking high center, whose periods are about two weeks or one month, but the location of high center remains quasi- stationary.