Document Type



Master of Science (MS)



First Advisor's Name

Hugh E. Willoughby

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Ping Zhu

Third Advisor's Name

Robert Burgman


Beta Gyres, Tropical Cyclone, Vortex Motion, Vorticity Advection, Vortex Rossby Wave, Cutoff Frequency, Streamfunction, Resonance, Barotropic-Nondivergent

Date of Defense



The linear Barotropic Non-Divergent simulation of a vortex on a beta plane is consistent with Willoughby’s earlier shallow-water divergent results in that it produced an unbounded accelerating westward and poleward motion without an asymptotic limit. However, Montgomery’s work which yielded finite linear drift speeds for his completely cyclonic vortex was inconsistent with ours. The nonlinearly-forced streamfunction exhibited a beta-gyre like structure, but with opposite polarity phase to the linear gyres. Utilization of the linear model with time-dependent, but otherwise beta-like, forcing revealed increasing magnitude and phase reversal in the neighborhood of a low cyclonic frequency. Here, the mean bounded vortex has an outer waveguide that supports Vortex Rossby Wave propagation that is faster than the mean flow and confined to a very narrow band of frequencies between zero and the Vortex Rossby Wave cutoff. The low frequency waves constitute the beta-gyre mode described previously by Willoughby.





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