Inhibition of Baroclinic Instability in Low-Resolution Models

Abstract

The inhibition of baroclinic instability in low-resolution quasi-geostrophic models is studied using a simplified second-order closure approximation. It is shown that this inhibition, which results in systematic overestimation of baroclinic energy and systematic underestimation of barotropic energy, is the result of spurious energy dissipation due to the use of inadequate lateral diffusion. Consequently, a possible methodology for the parameterization of baroclinic instability in low-resolution models is proposed, based on the construction of diffusion operators able to dissipate potential enstrophy while conserving energy exactly.