Vorticity Budget of the Easterly Wave in Relation to Cumulus Transport

Abstract

The vorticity budget of a numerically simulated easterly wave is studied, with special emphasis on examining the effects of cumulus convective transport. A quasi-geostrophic model is used. The easterly wave is generated by specifying a diabatic heating wave which represents the effects of deep cumulus convection. The dynamical and thermodynamical properties of the simulated wave resemble those of the classical easterly wave. The study shows that the effect of the cumulus transport of vorticity is to decrease the wave amplitude in the horizontal velocity field. This effect may explain the fact that strong weather activity is sometimes associated with very little perturbation in the prevailing easterlies.