The Two-Dimensional Response of a Tropical Jet to Propagating Lines of Convection

Abstract

This paper uses simple one- and two-dimensional models to investigate the influence of a propagating line of convective forcing on a tropical jet, representative of the African easterly jet. The results are used to infer changes in the environment of the forcing region, which would in reality tend to influence the evolution of the storm through convective mechanisms, which are not resolved here. From linear analytical solutions with a rigid lid it is found that the influence of the propagation of the forcing region is to intensify the response on the upstream side of the forcing: this result is confirmed in two-dimensional nonlinear simulations. When linear wave modes are computed in a basic state that includes the jet structure, small sensitivities to the basic-state jet are found. The two-dimensional nonlinear model has been used further to compute the change in the environmental structure as a result of the forcing. Principally, it is found that the modes of response to the forcing may be associated with characteristic changes in the basic-state shear, convective available potential energy (CAPE), and convective inhibition (CIN), which would be expected to have significant influence on the convective system itself.