On the dynamics of coupled envelope structures for barotropic-baroclinic interaction with Bottom Topography: Unequal depth case

Nonlinear barotropic-baroclinic interaction is significance in atmospheric and oceanic dynamics. Based on the existing equal depth two-layer quasi-geostrophic potential vorticity (2LQGPV) conservation model, this article further proposes the unequal depth 2LQGPV model hypothesis, that is, under the condition that the depths of the upper and lower fluid layers are unequal, the barotropic-baroclinic coupled nonlinear Schrödinger (NLS) equations describing the evolution of the Rossby wave amplitude are derived. The focus is on studying the evolution mechanism of the topography on the nonlinear barotropic-baroclinic interaction and its influence on the blocking effect. The results show that large topographic amplitude and small topographic frequency can delay the blocking, while small topographic amplitude and large topographic frequency will accelerate the fluctuation of Rossby waves and make the blocking appear earlier. At the same time, both convex and concave topographies enhance the northern branch of the dipole, showing a north-south asymmetry. The study reveals the modulation effect of topography on Rossby wave propagation, blocking effect and dipole evolution, deepens the understanding of the role of topography in nonlinear wave dynamics, and provides a theoretical basis for the prediction of atmospheric and oceanic circulation.