Estimating Large-Scale Vorticity Using VAD Products and Reflectivity

Abstract

Velocity-azimuth display (VAD) products (i.e., wind, divergence, deformations, etc.) and a Lagrangian advective scheme applied to the reflectivity factor field are jointly used to estimate vertical profiles of vorticity. The reflectivity field is assumed to be conserved over the time period between radar observations. The vorticity selected gives the best least squares fit between observed and predicted reflectivity fields. These results suggest that vorticity is retrieved with a precision better than about 1?10?1 s?1 for scales on the order of 100 km and larger. The vorticity profiles are consistent with U.S. National Weather Service's analysis. The surface value of vorticity, extrapolated from the estimated profiles, is also compared with the vorticity calculated from Oklahoma mesonet data. The agreement is within the estimated standard error.