Tropical Cyclone Motion and Evolution in Vertical Shear

Abstract

Abstract The motion and the evolution of tropical cyclone-like vortices in an environmental flow with vertical shear are investigated using a baroclinic primitive equation model. The study focuses on the fundamental dynamics of a baroclinic vortex in vertical shear, the influence of vortex structure, and the role of diabatic heating. The results show that the initial response of the vortex to the vertical shear is to tilt downshear. As soon as the tilt develops, the upper-level anticyclonic and lower-level cyclonic circulations begin to interact with each other. As a result of these interactions, the tilted axis of the vortex reaches a stable state after an initial adjustment, which varies with the structure of the vortex, its environmental flow shear, and the cumulus convective heating. The motion of an adiabatic vortex in vertical shear is controlled by both the steering of the environmental flow and vertical coupling mechanisms. Most of the vortices move with the environmental flow at about 650 hPa or ...