An observational study of electrical structure in convective regions of mesoscale convective systems

In this study, electric field (E) soundings through convective regions of mesoscale convective systems (MCSs) are examined. The data show a typical electrical structure exists in this region. The basic E profile in MCS convective region updrafts has three {dollar}rmvert Evert{dollar} peaks: a positive peak near 5 km height, a negative peak near 8 km, and a positive peak near 11 km. There are also numerous large lightning E changes at 6-10 km. In MCS updrafts, the basic charge structure consists of four charge regions alternating in polarity, with the lowest region positive and the highest region negative. The center of the main negative charge is higher in updraft soundings that have larger average balloon ascent rates. The basic E profile outside updrafts has five {dollar}rmvert Evert{dollar} peaks; the lowest three of these are below 5 km. Maximum electric field magnitudes of both polarities are larger and at lower heights in E soundings outside updrafts compared to those within updrafts of MCS convective regions. Inferred charge regions are shallower and have larger charge densities outside updrafts. The basic charge structure outside updrafts in MCS convective regions consists of six charge regions, alternating in polarity, with positive charge lowest. The average center height of the main negative charge is lower outside updrafts (5.5 km) than within updrafts (6.9 km) of MCS convective regions. These features within and outside updrafts are depicted in a new conceptual model of MCS convective region charge structure.; Soundings of E through two types of isolated thunderstorms are also examined and compared to those through MCS convective regions in this study. The finding that convective regions of MCSs, supercells, and New Mexican air mass storms have in common a basic electrical structure indicates that this structure may be typical of all thunderstorm convection.; Also in this study, typical electrical structures in MCS stratiform regions are compared to the electrical structures in MCS convective regions. Similarities and differences are depicted in an expanded conceptual model that includes the electrical charge, air flow, and reflectivity features for the stratiform region, the transition zone, and the convective region of mesoscale convective systems.