ABSTRACT

Tropical cyclones pose a very significant threat to life and property, and affect many people in many places around the globe. Progress towards better understanding of their structure and evolution thus has the potential for directly impacting society on a number of levels. The study of tropical cyclones may arguably be separated into three categories: motion, intensity change, and genesis. Progress has been made toward understanding the former but measurably less progress has been made towards better understanding of the latter two processes. This research will address certain aspects of tropical cyclone genesis and has the potential to significantly advance scientific knowledge and ultimately predictive skills in regard to tropical cyclones.

The genesis process is not yet rigorously and universally defined, but most would agree that it comprises a variety of events, such as formation of a low-level vortex from a mid-level vortex, and formation of a warm core thermodynamic structure from a cold core structure. This research will concentrate on the role of vortex merger in these processes. There have been a number of previous studies that strongly support the idea that the merger of multiple smaller vortices into a larger "parent" vortex is a key part of the genesis process. Presently, however, the details of how the merger process affects the specific structure of the resulting parent vortex have not been well studied or documented.

By uniquely applying concepts based on probabilistic solutions in two dimensional turbulence, this work will explore and document a method for predicting the exact structure of a parent vortex formed by multiple merger events. The method predicts the parent vortex structure based solely on knowledge of the combined circulation and energy of the smaller vortices that formed it. The method demonstrates that certain configurations of small vortices will merge to form a smaller, more intense parent vortex than other configurations that have the same total circulation. This is an important feature since the ability of the parent vortex to maintain itself and intensify further into an incipient tropical cyclone can depend strongly on its structure.

Since small-scale vortices are typically formed within clusters of cumulonimbi, and thus can be remotely measured to some degree, the results of this work might offer predictive insight into which cloud clusters have a better chance of undergoing tropical cyclogenesis.

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