Dynamics of nonlinear Rossby waves in zonally varying flow with spatial-temporal varying topography
Dynamics of nonlinear Rossby waves in zonally varying flow with spatial-temporal varying topography
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时空变化地形纬向变流中非线性罗斯贝波动力学
DOI：
10.1016/j.amc.2018.10.084
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发表时间：
2019
影响因子：
4
通讯作者：
Yin Xiaojun
中科院分区：
文献类型：
--
作者：
Zhang Ruigang;Yang Liangui;Liu Quansheng;Yin Xiaojun
本文在广义β近似下研究了纬向变化背景流中非线性Rossby波的动力学。考虑了纬向变化的背景流、时空变化的地形、势强迫和耗散对非线性Rossby波的影响。利用多尺度方法和微扰展开，导出了一个新的修正的变系数Rossby波振幅Korteweg-deVries方程。基于所得到的模型方程，分析了非线性Rossby波的物理机制.定性结果表明，在所选参数范围内，广义β和基本地形是激发非线性Rossby孤立波的重要因素。此外，纬向变化的流动影响波的线性相速度和线性增长或衰减特性。结果还表明，时空缓慢变化的地形，这是一个不稳定的机制，Rossby孤立波的演变，是一个因素的线性增长或衰减。为了验证所得到的模型方程的有效性，采用弱非线性方法和数值模拟方法对所得到的方程进行了求解，结果表明定性分析和定量解在解释本方程时是一致的。
In the present work, we investigate the dynamics of nonlinear Rossby waves in zonally varying background current under generalized beta approximation. The effects of the zonally varying background current, the spatial-temporal varying topography, the potential forcing and the dissipation on nonlinear Rossby waves are all taken into consideration. We derive a new modified Korteweg–deVries equation with variable coefficients for the Rossby wave amplitude with the help of multiple scales method and perturbation expansions. Based on the obtained model equation, the physical mechanisms of nonlinear Rossby waves are analyzed. Within the present selected parameter ranges, the qualitative results demonstrate that the generalized beta and basic topography are essential factors in exciting the nonlinear Rossby solitary waves. In addition, the zonally varying flow affects the linear phase speed and the linear growth or decay characteristics of the waves. The results also show that the spatial-temporal slowly varying topography, which represents an unstable mechanism for the evolution of Rossby solitary waves, is a factor in linear growth or decay. Furthermore, to validate the efficiency of the obtained model equation, a weakly nonlinear method and numerical simulation are adopted to solve the obtained equation and the results indicate the consistency between the qualitative analysis and the quantitative solutions in explaining the present equation.