Extended Abstract (96K)P1.31
From Asymmetric Heating to Axisymmetric Intensification
David S. Nolan, Princeton University, NOAA/GFDL, Princeton, NJ; and M. T. Montgomery
In previous work, the authors have presented a methodology for the study of fully three-dimensional, nonhydrostatic perturbations to balanced, tropical cyclone-like vortices. The method can be used both to determine the stability of such vortices, and to identify the structure and dynamics of unstable modes if they do exist. The method can also be used to study the linearized initial value problem, such that the evolution of arbitrary perturbations and their interaction with the basic-state vortex can be analyzed.
Here, we present the results of simulations of the evolution of initially thermal perturbations to the inner and outer cores of these idealized tropical cyclones. Such perturbations are hypothesized to be the result of localized bursts of convection in the vicnity of developing tropical storms. The evolution of these perturbations goes through two phases: first, there is rapid adjustment to quasi-gradient balance accompanied by the generation of rapidly propagating inertia-gravity waves. Second, the potential vorticity fields of the resulting quasi-balanced perturbations are sheared apart by the basic-state flow, leading to axisymmetrization. As seen in two-dimensional studies, axisymmetrization leads to upgradient momentum fluxes and localized accelerations of the basic-state vortex. Additional complexities arise due to the vertically varying structures of the basic state and the perturbations themselves. Comparisons to simulations in a fully nonlinear mesoscale model will also be presented.
Poster Session 1, Tropical Cyclones, Large-scale Dynamics and Convection
Monday, 29 April 2002, 11:00 AM-12:30 PM
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