Meso-βScale Potential Vorticity Anomalies and Rainbands Part II: Moist Model Simulations

Abstract

A two-dimensional semigeostrophic frontogenesis model is used to study meso-β scale potential vorticity anomalies as a possible cause for rainbands in midlatitude cyclones. The model includes water vapor and allows the formation of stratiform clouds. Simulation results indicate that height-dependent potential vorticity anomalies are effective mechanism causing the formation of rainbands. The shape and intensities of the rainbands depend sensitively on the structure of the initial anomalies, and the initial distribution of moisture. Model results show latent heat released in rainbands induces significant perturbations in the potential temperature and potential vorticity fields that affect the subsequent evolution of the rainbands. These heating induced anomalies may be a substantial source of inhomogeneities at the meso-β scale in the potential vorticity field of the atmosphere.