Doppler Velocity Signatures of Idealized Elliptical Vortices
Journal
Terrestrial, Atmospheric and Oceanic Sciences
Journal Volume
17
Journal Issue
2
Pages
429-446
Date Issued
2006
Author(s)
Abstract
Doppler radar observations have revealed a class of atmospheric vortices (tropical cyclones, tornadoes, dust devils) that possess elliptical radar reflectivity signatures. One famous example is Typhoon Herb (1996) that maintained its elliptical reflectivity structure over a 40-hour period. Theoretical work and dual-Doppler analyses of observed tropical cyclones have suggested two physical mechanisms that can explain the formation of two types of elliptical vortices observed in nature, namely, the combination of a circular vortex with either a wavenumber two vortex Rossby wave or a deformation field. The characteristics of these two types of elliptical vortices and their corresponding Doppler velocity signatures have not been previously examined. Idealized elliptical vortices consisting of a Rankine vortex combined with wavenumber two disturbances are constructed and sampled by a hypothetical Doppler radar. The Doppler velocity patterns of all wavenumber two cases shown in this study are visually similar. The characteristics of the two-dimensional flow patterns and the corresponding Doppler velocities produced by an idealized vortex Rossby wave and deformation field are illustrated. The ground-based velocity track display (GBVTD) single Doppler vortex wind retrieval technique was performed on these two types of elliptical vortices.
SDGs
Type
journal article