Observational Study of a Microburst-Producing Storm Part IV:Fine Scale Analysis

Abstract

Data are presented for several microburst events as they occurred on 5 August 1982 at 1845 LST. The kinematic, dyamic, and thermodynamic structures of these storms were investigated using dual-Doppler data collected during the JAWS project. Fields of storm-relative wind and reflectivity were derived using the objective analysis scheme with 0.25 km horizontal grid spacing and compared with a previous study which used 0.5 km horizontal grid spacing. There were five layers in the vertical ranging from 0.25 to 1.25 km. Vertical velocities were calculated from the anelastic continuity equation by integrating upward from the surface to the top of the atmospheric boundary layer. The thermodynamic retrieval method was employed to retrieve fields of perturbation pressure and temperature from the Doppler derived winds using the three momentum equations.
Results show that several features undetected at the 0.5 km grid scale become apparent at the 0.25 km grid. Further, most features observed in this study become strikingly more apparent both in magnitude and appearance than the earlier study using 0.5 km horizontal grid spacing. The quality and resolution of dual-Doppler derived winds are critical to the success of a thermodynamic retrieval technique.

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