HR: 10:50h
AN: AE51B-02    [PDF]
TI: Initial Electrification of Thunderstorms: Evidence for a Connection Between Precipitation and Electrical Charging
AU: * Stolzenburg, M
EM: mstolzen@phy.olemiss.edu
AF: University of Mississippi, Department of Physics and Astronomy PO Box 1848, University, MS 38677 United States
AU: Marshall, T
EM: marshall@olemiss.edu
AF: University of Mississippi, Department of Physics and Astronomy PO Box 1848, University, MS 38677 United States
AU: Krehbiel, P
EM: krehbiel@ibis.nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Rison, W
EM: rison@arctic.nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Thomas, R
EM: thomas@ee.nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Winn, W
EM: winn@loon.nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Hunyady, S
EM: hunyady@nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Aulich, G
EM: aulich@grosbeak.nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AU: Ramig, N
EM: nramig@nmt.edu
AF: New Mexico Institute of Mining and Technology, Langmuir Laboratory for Atmospheric Research 801 Leroy Place, Socorro, NM 87801 United States
AB: In this study we investigate the initial electrification of three thunderstorms using surface electric field (E) measurements, radar measurements, lightning mapping array data, and in situ balloon E soundings. Our data support previous results and show a close correlation between the location of the developing precipitation core and the location of the early charges in each storm. In one cell the initial deflection of the surface E was in the direction of enhanced fair weather (negative) E, indicating an inverted dipolar charge distribution overhead. During this time, the only substantial precipitation (e.g., greater than 40 dBZ echo) was located below the altitude of the -10$^{o}$C isotherm. This suggests that the charging in the mixed phase region was occurring at temperatures warmer than the charge reversal temperature. In addition, the first two balloon soundings in this cell indicate that the lowest charge was positive and moved downward, and thus was presumably carried on precipitation. As precipitation subsequently developed in colder parts of the cloud, the surface E became dominated by a normal dipole. The first lightning flash was a normal intracloud flash within and above the developing precipitation core. Multiparameter radar coverage for the second case began just after the initial deflection in the surface E. The initial E deflection was in the foul weather direction, as for a normal positive dipole growing overhead. At the same time, upward growth of a substantial precipitation core occurred, with much of the core located above the altitude of -10$^{o}$C. The first lightning flash in this cell was a normal intracloud flash within and above the developing precipitation core. In the third case, an early explosive precipitation growth phase occurred between 6 and 8 km altitude. A balloon sounding during this growth phase and before the first lightning flash revealed a normal dipole structure, with positive charge centered at 8.7 km (-20$^{o}$C) and negative charge centered at 7.4 km (-10$^{o}$C). The first lightning flash initiated at 8.8 km and revealed positive charge above the precipitation core (and near the top of the updraft) and negative charge beside the precipitation core, in agreement with the balloon sounding. The data from these three cases support the idea that precipitation particles and electrical charge develop together during the initial electrification of thunderstorms.
DE: 3304 Atmospheric electricity
DE: 3314 Convective processes
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting