A NUMERICAL INVESTIGATION OF THE IMPACT OF LATENT HEATING UPON THE STRUCTURE OF ACTIVE COLD FRONTS

A 3D mesoscale model is applied in a marine cold front case in order to investigate the impact of latent heating upon the structure of active cold fronts.Results of the moist and dry simulations are compared to stress the effects of moist processes.It is found that both the temperature gradient and the cyclonic vorticity across the frontal zone are considerably increased due to the latent heating,especially in the lower troposphere.It is also noted that the cross-front ageostrophic direct circulation is more fully-developed and better organized in the moist case than in the dry case.The latent heating tends to enhance the intensity of the cross-front circulation.especially its ascending branch.Most importantly.our results indicate the important contribution by the latent heating to the formation of the intense narrow rising cell just above the leading edge of the cold front.