The effect of background flow shear on the topographic Rossby wave
Tóm tắt
Due to the ubiquitous steep continental shelf slope in the East China Sea, topographic Rossby waves are very common when the Kuroshio Current flows along the slope, and of great importance in the water and energy exchange between the open ocean and coastal sea. To examine the structural characteristics of topographic Rossby wave, we use stretching transform of time and space and perturbation method to get the analytic solution of potential vorticity equation with topography. For a given background flow v = v0 + δx, the effect of background flow shear is discussed. The main conclusions are drawn that background flow shear is required for the existence of solitary Rossby waves; for flow shear δ < 0 (δ > 0), anticyclonic (cyclonic) solitary Rossby waves exist and their zonal structure tilts eastward (westward); the phase speed of solitary Rossby waves is related to the amplitude and flow shear intensity; solitary Rossby waves are non-dispersive waves, and the width of solitary waves is inversely proportional to the intensity of the flow shear. Furthermore, these theoretical results are used to explain the propagation speeds and distributions of eddies along the Kuroshio Current in the East China Sea. In addition, these results could be applied to other areas with similar meridional current and topography.
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