A simplified scheme to simulate asymmetries due to the beta effect in barotropic vortices

Abstract

This approach, based on the time integration of the nondivergent barotropic vorticity equation, was developed to generate asymmetric vortex structure for inclusion in the initial conditions for the GFDL Hurricane Model. The simplification is derived from truncation of an azimuthal wavenumber expansion of the vorticity field variables. In order to determine the optimum lowest-order system, the influence of other wavenumbers (specifically 0, 2, and 3) on the asymmetric dipolar (wavenumber 1) structure and the associated vortex drift was investigated by comparing the results of a hierarchy of models differing in truncation level. The model truncated at wavenumber 2 and, including time-dependent symmetric flow was chosen as the optimum system. -from Authors