Instability and Splitting of Mesoscale Rings using a Two-Layer Quasi-Geostrophic Model on an f-Plane

摘要: Abstract Asymmetric instability of a circular Gaussian ring and evolution shape in nonlinear case are studied using two-layer quasi-geostrophic model on an f plane. Ring behavior is classified F-λ plane with other parameters fixed, where F internal rotational Froude number associated model, λ ratio the rotation speed lower layer to that upper layer. In range concerned 0, mode having azimuthal wavenumber 2 fastest growing, followed by 3. The more unstable as increases decreases, larger corresponds smaller density difference or size. By numerical calculations, for which initial perturbation superimposed ring, into four groups from most stable case: (i) splits two small rings, (ii) rapidly becomes slender ellipse a...