This project studies hurricane dynamics with a particular emphasis on processes that affect the intensity of the tropical cyclone by mixing in moist air or dry air from different sources. Since penetration to the storm core or eye-wall is a nonlinear mixing problem, the investigators intend to apply methods from dynamical systems theory to help them understand transport and mixing processes, both on the scale of the eye/eye-wall system with its mesovortices in the eye-wall, and on the scale of the vortex as a whole. Part of the motivation for this work is that existing theory for maximum wind intensity, based on assumptions of axisymmetry can significantly under-predict the intensities seen in high-resolution numerical models of hurricanes. The formation of eye-wall mesovorticies and latent heat release from moist air transported asymmetrically into the hurricane eye-wall may help explain this difference.
The work to be done includes analyzing output from high-resolution hurricane simulations to determine distinguished hyperbolic orbits and their stable and unstable manifolds, implementing new methods for analyzing Lagrangian mixing, finding low-dimensional approximations to phases of hurricane evolution, and a search for a set of parameters that may be used to predict maximum wind intensity.
It is anticipated that the results of this theoretical work will help in the design of future field experiments, contribute to a better understanding of the processes responsible for fluctuations in hurricane intensity, and provide a basis for better predictions of hurricane intensity.
