摘要：

An earlier analytic theory for the motion of a barotoropic vortex in a zonally varying basic shear flow on a beta-plane is consolidated and extended. It is shown that the theory can be derived from a power-series expansion of variables representing the vortex asymmetry in terms of a single nondimensional parameter ϵ = BL²/U, where B is the Meridional gradient of basis state absolute vorticity and L and U are the lenght and velocity scales, respectively, for the outer part of the vortex. The derivation requires inter alia that ϵ ≪ 1 and that the magnitude of the basis flow scales with ϵ. Insight is provided into the dynamics of vortex motion when the latter condition is not fulfilled, as in cases of moderate and large shear.

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