PRECIPITATION CHARGE AND SIZE MEASUREMENTS IN THE STRATIFORM REGION OF 2 MESOSCALE CONVECTIVE SYSTEMS

We measured the charge and size of precipitation particles with instrumented free balloons in the trailing stratiform regions of two different mesoscale convective systems (MCSs) in Oklahoma. Each of these stratiform regions had a different type of vertical electric field structure, one of each of the two types commonly found in MCS stratiform regions. Using an instrument that measured precipitation charge from 4 to 400 pC and equivalent diameters from 0.8 to 8.0 mm, are found that (1) the particles measured were not the major charge carriers in these storms, implying that smaller particles were responsible for the measured field, (2) there was no obvious relation between precipitation charge and size or polarity and size, (3) the precipitation size distribution in and near the transition zone consisted of two independent populations, one centered at 2.6 mm and one at 4.9 mm, (4) the two lower charge layers in these storms were likely created by in situ charging processes, and (5) net precipitation charge density was small because nearly equal amounts of positive and negative precipitation charge existed at all altitudes measured.