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Gregory M. Zhikharev 《地球物理与天体物理流体动力学》2013,107(3-4):259-279
Abstract A spectral low-order model is proposed in order to investigate some effects of bottom corrugation on the dynamics of forced and free Rossby waves. The analysis of the interaction between the waves and the topographic modes in the linear version of the model shows that the natural frequencies lie between the corresponding Rossby wave frequencies for a flat bottom and those applying in the “topographic limit” when the beta-effect is zero. There is a possibility of standing or eastward-travelling free waves when the integrated topograhic effect exceeds the planetary beta-effect. The nonlinear interactions between forced waves in the presence of topography and the beta-effect give rise to a steady dynamical mode correlated to the topographic mode. The periodic solution that includes this steady wave is stable when the forcing field moves to the West with relatively large phase speed. The energy of this solution may be transferred to the steady zonal shear flow if the spatial scale of this zonal mode exceeds the scale of the directly forced large-scale dynamical mode. 相似文献
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Typhoon is regarded as a convergent,modified Rankine vortex.Based on the vorticity equations written attwo levels,higher and lower in the troposphere,typhoon motions are discussed in this study.The analyticalexpressions of vortex motion direction and speed have been derived for simple homogeneous basic flows at twolevels.The expressions indicate that in the easterties,vertical wind shear enhances the steering of east flow,causing the vortex moving westward faster,otherwise,in the westerlies,it reduces the steering of the west flow,causing the vortex moving eastward slower.These results explain theoretically that“cyclones in the easterliesmove to the right of,and faster than the basic flow;conversely,cyclones in the westerlies move to the left of,andslower than the basic flow.” 相似文献
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