Hurricane maximum intensity: past and present

Improvements in hurricane intensity forecasting have lagged far behind improvements made in the forecasting of hurricane track. In an effort to improve the understanding of the hurricane intensity dilemna, several attempts have been made to compute an upper bound on hurricane intensity. This thesis investigates the strides made into determining the Maximum Potential Intensity (MPI) of hurricanes. First, the MPI theories of Miller (1958) and Holland (1997), which rely heavily on the presence of convective instability in the ambient tropical atmosphere in regulating the MPI, are reviewed. The theories of Kleinschmidt (1951), Malkus and Reihl (1960), and Emanuel (1986-1997), each of which does not rely on the presence of ambient convective instability are reviewed next.

Using the axisymmetric hurricane models of Ooyama (1969), Emanuel (1989, 1995b), and Rotunno and Emanuel (1987), in addition to observational evidence, we test each theory. We determine that ambient convective instability plays a minor role in the determination of the MPI, concluding that the Emanuel model is the closest theory to providing a useful calculation of MPI. However, several shortcomings are revealed in Emanuel's theory showing the need for more basic research on the axisymmetric dynamics of hurricanes, as well as continued research into the impacts of the oceanic mixed layer and asymmetric processes such as vortex Rossby waves and eyewall mesovortices.

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