Comment on "VLF signatures of ionospheric disturbances associated with sprites" by Inan et al.

Abstract

The events described by Inan et al. [1995b] in the paper under comment here, and earlier as "VLF sprites" [Inan et al., 1995a], refer to VLF scattering confined to a very narrow range about the forward direction. This must be produced by horizontally extensive (few hundred km) ionospheric disturbances with a Gaussian shape as suggested by them. Such scattering is quite at odds with the very wide angle VLF scattering (even to 180°) observed by Dowden et al. [1995]. The reason for this is not due to differences in receiving equipment or data interpretation, but due to the scattering sources being quite different in size and shape. The narrow angle scattering sources may be the recently discovered "elves" (Emissions of Light and VLF perturbations from EMP) produced by the electromagnetic pulse (EMP) of lightning. The wide angle scattering sources have been identified as the thin (∼1 km) vertical columns of plasma as predicted by Dowden et al. [1994] and seen as the luminous columns of sprites.