Severe Storm Latent Heat Release: Comparison of Radar Estimate Versus a Numerical Experiment

Abstract

The time variation of mass-integrated liquid water and latent heat release for a severe thunderstorm in marked vertical wind shear is investigated for an actual Oklahoma storm and for a two-dimensional numerical modeling experiment. For the actual storm, an approximate continuity equation for liquid water variation is used together with profiles of radar reflectivity. Empirical relationships are utilized to determine the rainfall rate (flux) and liquid water content from the radar reflectivity profiles. Estimates of total storm water mass are obtained from the reflectivity profiles for the volume swept by the radar beam in the vertical. The downdraft evaporation rate is parameterized on the basis of a previous study which estimated this quantity as a residual in the continuity equation for liquid water mass. To estimate latent heat release and total liquid water mass from the numerical model, the two-dimensional cloud is extended to a three-dimensional region whose horizontal cross sections are ellipses approximating typical observed PPI radar echo shapes. At each level, horizontal averages of relevant integrands are assumed equal to those in the model plane. It is found on the basis of these analyses that at maturity, the actual storm and the model storm exhibit comparable magnitudes with respect to both latent heat release and liquid water content.