Numerical Simulation of Frontogenesis in a Moist Atmosphere

Abstract This paper describes the effect of condensation and evaporation on mesoscale frontal circulations in a two-dimensional numerical model. Utilizing an explicit scheme for the prediction of water vapor, cloud water and rainwater, the model is used to investigate the interactions between convection and the larger-scale environment. The model results are qualitatively compared with results of theoretical and observational studies, including those from the recent Severe Environmental Storms and Mesoscale Experiment-Atmospheric Variability Experiment (SESAME-AVE). Three major differences are observed in a comparison of the moist and dry simulations: 1) The speed of the upper- and lower-level jets was significantly higher in the moist case, 2) The intensity of the ageostrophic circulations in the moist simulation was much stronger, 3) The vertical velocity field in the moist case was characterized by a banded structure not present in the dry case.