Tropical Cyclogenesis via Non-Axisymmetric Upscale Energy Cascade and Its Disruption by Vertical Shear

Colorado State University, Fort Collins CO

Investigators

Abstract

This project involves studies of tropical cyclogenesis and development along three avenues. Previous work by the PI and his group advanced the understanding of the axisymmetrization for vortices where the mean vortex intensifies at the expense of the small-scale vorticity anomalies through an upscale energy cascade process using a fairly simple model. As the first avenue of investigation, the PI will further explore the validity of the theory using a more realistic three-dimensional cloud-resolving model under various initial conditions. The second avenue is to examine and determine the conditions for the disruptions of the upscale energy cascade. If a barotropic vortex is tilted from its rotation axis, it may or may not return to its upright position (alignment) and disrupt the upscale energy cascade. This work seeks to determine the conditions that enable a finite Rossby number vortex to resist the adverse effects of vertical shear. The third avenue will be the testing of the theory using the airborne Doppler-radar data from a tropical cyclone field experiment done in 1991. This part of the work will be done in collaboration with Drs. Frank Mark and Paul Reasor of HRD and Prof. Lance Bosart of SUNY/Albany. The results of this project have the potential to enhance the understanding of tropical cyclogenesis and to improve the prediction of tropical cyclone intensity.