Lightning in the Ionosphere with C/NOFS

Abstract

Abstract : The Lightning Detector instrument, which is part of the VEFI (Vector Electric Field Instrument) on-board the C/NOFS (Communications / Navigation Outage Forecast System) was jointly developed with support from NASA and the National Science Foundation. Once lunched, the Air Force Office of Scientific Research granted the University of Washington the needed support for the scientific analysis of those data to investigate the influence of lightning on the ionospheric plasma. Initially with NASA support, and concluding with this AFOSR grant support, we have prepared the lightning data for public access (see http://cdaweb.gsfc.nasa.gov/istp_public/ ). This work has quantified the electric field and optical lightning measurements in the ionosphere as never before done. Due to the unique, near equatorial, C/NOFS orbit, practically every orbit passed over active thunderstorms. Results include: observation of lightning transients in the ionospheric electric field above ambient background noise from lightning over 12,000 km from the subttack point; detailed comparison of the optical transient with global lightning source locations and timing of such accuracy that errors in the vehicle clock were detected; report of the close relationship between ionospheric plasma density irregularities and the occurrence of optical lightning activity; and the observation that lightning electric fields were often the largest field inside density cavities caused by the plasma phenomena known as Spread-F.