On the Relationship between Lightning and Equatorial Ionosphere Density Irregularities

The C/NOFS (Communications/Navigation Outage Forecast System) satellite was launched in April 2008 and carries high time resolution vector electric field and optical transient detectors. Using calibrated optical power-time profiles from the C/NOFS lightning detector (LD), along with data from the WWLLN (World Wide Lightning Location Network) which provides timing, power, and source location for lightning events, we examine the detailed vector electric field wave data gathered by the C/NOFS probes during periods of lightning activity. Using 32 ksample/sec burst data, we demonstrate the close one-to-one coincidence of lightning sferics observed on the ground with the VLF whistler waves observed at the satellite. We then compare lightning electric field transients measured on the satellite within a plasma density cavity, such as a spread-F depletion, with those measured by the satellite probes within a stable ionosphere. We demonstrate that during lightning events, the ELF and VLF electric field amplitude within these density depletions and associated irregularities can be dominated by contributions from the electric field transients associated with lightning.