VLF SIGNATURES OF IONOSPHERIC DISTURBANCES ASSOCIATED WITH SPRITES - COMMENT

The events described by Inan er al. [1995b] in the paper under comment here, and earlier as ''VLF sprites'' [Inan et al., 1995a], refer to V LF scattering confined to a very narrow range about the forward direct ion. This must be produced by horizontally extensive (few hundred km) ionospheric disturbances with a Gaussian shape as suggested by them. S uch scattering is quite at odds with the very wide angle VLF scatterin g (even to 180 degrees) observed by Dowden et al. [1995]. The reason f or this is not due to differences in receiving equipment or data inter pretation, but due to the scattering sources being quite different in size and shape. The narrow angle scattering sources may be the recentl y discovered ''elves'' (Emissions of Light and VLF perturbations from EMP) produced by the electromagnetic pulse (EMP) of lightning. The wid e angle scattering sources have been identified as the thin (similar t o 1 km) vertical columns of plasma as predicted by Dowden et al. [1994 ] and seen as the luminous columns of sprites.