Multiple-Parameter Radar Observations of Isolated Florida Thunderstorms during the Onset of Electrification

Abstract A prime objective of the Convection and Precipitation/Electrification experiment was to Study the electrification of Florida thunderstorms in greater depth using the National Aeronautics and Space Administration/United States Air Force electric field mill network; a small fleet of aircraft; the dual-frequency, dual-polarization CP-2 radar of the National Center for Atmospheric Research (NCAR), and other radars including the NCAR Doppler CP-3 and CP-4. Analyses of three small, isolated storms on 19 July 1991 suggest that the onset of electrification coincides with the appearance of significant volumes of differential reflectivity, indicative of liquid raindrops larger than 2-mm diameter, above the −7°C level accompanied by the nearly simultaneous appearance of significant depolarization, initially associated with the freezing of these drops. Although the relationship of the onset of electrification to various aspects of the radar reflectivity factor Z are more ambiguous, a rapid increase in the al...