Date of Award


Document Type


Degree Name

Master of Science


Department of Engineering Physics

First Advisor

Ronald P. Lowther, PhD


The primary purpose of this research is to provide guidance to forecasters from the Joint (Air Force/Navy) Typhoon Warning Center (JTWC) in Pearl Harbor to use in differentiating between the stages of extratropical transition (ET) of tropical cyclones (TCs). Not only is ET relevant to the Department of Defense, since JTWC stops providing TC warnings once they have undergone ET, but it is also applicable to the meteorological community since there currently "is no commonly accepted definition of ET" (Jones et al 2003). This research compares the results of a conceptual model of ET using subjective satellite analysis with the results of objective indicators based on Navy Operational Global Atmospheric Prediction System (NOGAPS) model analyses. The ultimate goal is to find a way to reduce the negative impact of incorrect TC forecasting by providing tools which are more objective in defining stages of ET. This work discusses the birth, growth, and death of TCs by describing what energy sources are necessary for their growth and dissipation. Recent studies provide a conceptual model of ET with definitions of two stages and ways to use satellite analysis to identify them (Klein et al. 2000). While this conceptual model was being analyzed with data from the western North Pacific Ocean, TCs were also being analyzed using data from the Atlantic Ocean (Hart and Evans 2001). The research from the Atlantic led to the exploitation of objective indicators in a hodograph-like display (Evans and Hart 2003).

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