A Diagnostic Study of the Vorticity Balance at 200 mb in the Tropics During the Northern Summer

Abstract

The linearized vorticity equation is used to diagnose the seasonal mean vorticity field at 200 mb in the tropics from Krishnamurti's observed mean horizontal divergence and mean zonal wind fields for June?August 1967. The generation of vorticity by the seasonal mean divergence cannot be balanced by vorticity advection. It is found, rather, that very rapid damping of the vorticity must be specified to obtain agreement with the observed vorticity field. It is conjectured that vertical transport of vorticity by cumulus convection is the mechanism responsible for the short decay time for the 200-mb vorticity field.