Detection of daytime sprites via a unique sprite ELF signature

On August 14, 1998, 3 separate daytime sprite events were detected via a unique extremely low frequency (ELF) sprite signature. The onset of the sprite ELF signatures was delayed by 11.0-13.2 ms from positive cloud-to-ground strokes which had attained exceptionally large charge moment (charge times height) changes of 3900-6100 C.km. It is shown that a charge moment change of 6100 C.km may have been sufficient for conventional breakdown at similar or equal to 54 km altitude, assuming an experimentally measured ion: conductivity profile of Holzworth et al., [1985]. The daytime sprites themselves contained unusually large charge moment changes of similar or equal to 2800 C.km, similar or equal to 1200 C.km, and similar or equal to 910 C.km.