DETECTION AND LOCATION OF RED SPRITES BY VLF SCATTERING OF SUBIONOSPHERIC TRANSMISSIONS

Scattering by the conductive columns of red sprites of VLF waves (''VL F sprites'') traveling in the Earth-ionosphere waveguide is characteri zed by wide angle scattering (to 180 degrees). This enabled the first VLF detection of sprite conductivity and is now used routinely for spr ite detection and location by measurement of the phase and amplitude a t both of the frequencies transmitted by NAA, NSS, NLK and NPM. In a b lind test using only one VLF receiver and the first three of these tra nsmitters, all of the VLF events fitting the criteria for VLF sprites were found to correspond to optical sprites and virtually all of the s prites observed optically corresponded to VLF events. Using only a sin gle receiver in the high noise environment of local thunderstorms enab led the range to the sprite to be found to within 100 km and the direc tion to within 90 degrees. Use of a large number (similar to 10) of su itably spaced antennas greatly increases the location accuracy and pro vides some information on the lateral structure of sprite conductivity .