Conditional convective heating in a baroclinic atmosphere: a model of convective frontogenesis

Abstract

It is shown here that there exists a regime of balanced frontogenesis that is forced almost entirely by the diabatic heating due to convection at a front. This theory is explored in the context of the two-dimensional semigeostrophic equations with an Eady basic state: convection is parameterized to be dependent on the low-level moisture convergence of the cross-frontal ageostrophic flow, in accordance with recent diagnostic studies. The significant result is that the growth rate of the convective frontal system becomes independent of the total wavelength of the domain once the diabatic heating exceeds a relatively large threshold magnitude. In this regime the frontal zone has a width and structure dependent on the heating magnitude but not on the wavelength. The system is described as "solitary' or "isolated' since the dynamics are self-contained and independent of the far field. -from Authors