Master of Science (MS)
Hugh E. Willoughby
Vortex Rossby Waves, Vorticity, Wave Energy, Critical Radius, Cut-off Frequency, Tropical Cyclone, Streamfunction, Barotropic Non-divergent, Wavenumber 2 Forcing
Date of Defense
Wavelike spiral asymmetries are an intriguing aspect of Tropical Cyclone dynamics. Previous work hypothesized that some of them are Vortex Rossby Waves propagating on the radial gradient of mean–flow relative vorticity. In the Intermittently Forced Vortex Rossby Wave theory, intermittent convection near the eyewall wind maximum excites them so that they propagate wave energy outward and converge angular momentum inward. The waves’ energy is absorbed as the perturbation vorticity becomes filamented near the outer critical radii where their Doppler–shifted frequencies and radial group velocities approaches zero. This process may initiate outer wind maxima by weakening the mean–flow just inward from the critical radius. The waves are confined to a relatively narrow annular waveguide because of their slow tangential phase velocity and the narrow interval between the Rossby wave cut–off frequency, where the radial wavenumber is locally zero, and the zero frequency, where it is locally infinite.
Cotto, Amaryllis, "Intermittently Forced Vortex Rossby Waves" (2012). FIU Electronic Theses and Dissertations. Paper 553.