HR: 0830h
AN: AE21A-1101    [PDF]
TI: Measurements of Continuing Currents in Lightning using ULF Magnetic Fields
AU: * Swaminathan, A
EM: as75@ee.duke.edu
AF: Duke University, 130 Hudson Hall, Dept. of Electrical and Computer Engineering, Durham, NC 27708 United States
AU: Cummer, S A
EM: cummer@ee.duke.edu
AF: Duke University, 130 Hudson Hall, Dept. of Electrical and Computer Engineering, Durham, NC 27708 United States
AU: Fuellekrug, M
EM: fuellekr@geophysik.uni-frankfurt.de
AF: University of Frankfurt Am Main, Institute for Meteorology and Geophysics,, Frankfurt, 60323 Germany
AU: Lyons, W
EM: walyons@mail.frii.com
AF: FMA Inc., Forensic Meteorology and Geophysics Associates, Inc., Fort Collins, CO 80524 United States
AB: Because they are difficult to measure, relatively little is known about the long duration continuing currents that are present in some lightning flashes despite their being one of the most damaging lightning processes. We use a combination of the Ultra Low Frequency (ULF) magnetic fields recorded at three stations (Santa Cruz, California, Socorro, New Mexico, and Saskatoon, Canada) and NLDN from 11 July to 12 August 1998 to detect and measure the amplitude and duration of the continuing currents which occur after some lightning flashes. Continuing currents of up to 450 milliseconds duration and peak amplitudes of up to 200 kA-km have been detected by our analysis. We report the frequency of occurrence of these continuing currents, largest and longest recorded continuing currents, the total charge moment of the continuing currents and the storm to storm variability of these currents. We will also address whether these continuing currents occur during the day or night, whether few storms produce almost all the lightning currents, and how the current strength is related to other lightning flash parameters so that we can have a better understanding of the basic meteorological conditions under which these continuing currents occur.
DE: 3324 Lightning
SC: Atmospheric and Space Electricity [AE]
MN: 2003 Fall Meeting