Sutyrin Georgi G.
Russian Academy of Sciences, P. P. Shirshov Institute of Oceanology, 23 Krasikova Street, Moscow 117218, Russia.
Chaos. 1994 Jun;4(2):203-212. doi: 10.1063/1.166004.
Large, long-lived vortices, surviving during many turnaround times and far longer than the dispersive linear Rossby wave packets, are abundant in planetary atmospheres and oceans. Nonlinear effects which prevent dispersive decay of intense cyclones and anticyclones and provide their self-propelling propagation are revised here using shallow water equations and their balanced approximations. The main physical mechanism allowing vortical structures to be long-lived in planetary fluid is the quick fluid rotation inside their cores which prevents growth in the amplitude of asymmetric circulation arising due to the beta-effect. Intense vortices of both signs survive essentially longer than the linear Rossby wave packet if their azimuthal velocity is much larger than the Rossby wave speed. However, in the long-time evolution, cyclonic and anticyclonic vortices behave essentially differently that is illustrated by the conservative intermediate geostrophic model. Asymmetric circulation governing vortex propagation is described by the azimuthal mode m=1 for the initial value problem as well as for steadily propagating solutions. Cyclonic vortices move west-poleward decaying gradually due to Rossby wave radiation while anticyclonic ones adjust to non-radiating solitary vortices. Slow weakening of an intense cyclone with decreasing of its size and shrinking of the core is described assuming zero azimuthal velocity outside the core while drifting poleward. The poleward tendency of the cyclone motion relative to the stirring flow corresponds to characteristic trajectories of tropical cyclones in the Earth's atmosphere. The asymmetry in dispersion-nonlinear properties of cyclones and anticyclones is thought to be one of the essential reasons for the observed predominance of anticyclones among long-lived vortices in the atmospheres of the giant planets and also among intrathermoclinic eddies in the ocean.
大尺度、寿命长的涡旋在行星大气和海洋中大量存在，它们能在多个反转时间内存活，且比色散线性罗斯贝波包存活的时间长得多。本文利用浅水方程及其平衡近似，对阻止强烈气旋和反气旋色散衰减并使其自推进传播的非线性效应进行了修正。行星流体中涡旋结构能够长期存在的主要物理机制是其核心内部流体的快速旋转，这阻止了由β效应引起的不对称环流振幅的增长。如果两个方向的强烈涡旋的方位角速度远大于罗斯贝波速，那么它们的存活时间将比线性罗斯贝波包长得多。然而，在长期演化过程中，气旋和反气旋涡旋的行为本质上有所不同，保守的中间地转模型对此进行了说明。对于初值问题以及稳定传播的解，控制涡旋传播的不对称环流由方位角模式m = 1描述。气旋涡旋由于罗斯贝波辐射而向西极向移动并逐渐衰减，而反气旋涡旋则调整为非辐射孤立涡旋。假设核心外部方位角速度为零，同时向极向漂移，描述了强烈气旋随着其尺寸减小和核心收缩而缓慢减弱的过程。气旋相对于搅拌流的极向运动趋势与地球大气中热带气旋的特征轨迹相对应。气旋和反气旋在色散 - 非线性特性上的不对称被认为是在巨行星大气中的长期存在的涡旋以及海洋内斜压涡旋中反气旋占主导地位的一个重要原因。
