Instabilidade baroclínica como gatilho para o desprendimento de vórtices da CNB: um estudo de caso

Abstract

This work aims to verify whet her baroclinic instability might act as a mechanism for the eddies shedding off from the superficial North Brazil Current retroflection (NBC). For this, we analyzed energy of the horizontal velocities field for a specific case where a subsurface eddy was overlaid by a surface eddy alongside its trajectory. Thus, the me an potential vorticity gradient profile and the available potential energy flux (Evar) direction were calculated. Hence, it was possible to observe that positive Evar values were progressively getting closer to the surface at each time step. This suggest that there is a bigger tendency on eddy formation at surface over time. In this way, at the last analyzed time step, it was noted the presence of a surface eddy, which indicates that, at least on this case, the baroclinic instability might act as a mechanism for pinching off eddies from the superficial NBC retroflection. Although, we emphasize that the studied process has a certain non-linearity to be fully explained only by this dynamics, in order that other process such as Rossby waves at the NECC, barotropic instability, among other, may as well act shedding edd ies.