Interaction of a baroclinic vortex with background shear: application to hurricane movement

Abstract

The hurricane is represented in a two-layer quasigeostrophic model as a point source of mass and zero potential vorticity air in the upper layer, collocated with a point cyclone in the lower layer. The model is integrated by the method of contour dynamics and contour surgery. The results show that Northern Hemisphere tropical cyclones should have a component of drift relative to the mean flow in a direction to the left of the background vertical shear. The effect of weak shear is also found to be at least as strong as the β effect, and the effect is maximized by a certain optical ambient shear. The behavior of the model is sensitive to the thickness ratio of the two layers and is less sensitive to the ratio of the vortices' horizontal scale to the radius of deformation. Storms with stronger negative potential vorticity anomalies tend to exhibit more vortex drift. -from Authors