Highly localized energy transfer induced by the interaction between a large vortex and four small vortices

Abstract

The scale interaction is simulated using a two-dimensional barotropic model with an initial condition of a large-scale vortex accompanied with four small-scale vortices. We show that both direct and inverse energy cascades occur simultaneously and that the spatial distribution of energy transfer flux across a moderate length scale is characterized by a highly localized configuration, which contains several closed systems with a spatial scale of 50-100 km embedded in two wave trains. This would imply that the temporal change of enstrophy at closed centers is more complex than that at noncenters. The increase of complexity is further correlated with amplification of the enstrophy difference, which is the value of enstrophy at t = 24 h minus that at the initial time.