Conjugate Lightning-Induced Electron Precipitation Observations and Associated Magnetospheric Properties

Ground-based VLF remote sensing has been used for over 50 years to study lightning-induced electron precipitation (LEP) from the Earth's radiation belts. Comparatively few simultaneously conjugate LEP events, which occur at both ends of a closed geomagnetic field line at the same time, have been reported. Theoretical analyses of conjugate LEP have related the relative timing of the events observed in the two hemispheres (i.e., the interhemispheric timing properties) to magnetospheric processes. Nevertheless, experimental observations of conjugate LEP report widely conflicting interhemispheric timing observations. This paper presents 46 conjugate LEP events detected by the University of Florida's North American VLF (NAV) array. We demonstrate that VLF signal processing techniques affect the calculation of interhemispheric timing statistics (and provide a resolution); we demonstrate experimentally that ducted and non-ducted LEP events exhibit different statistical timing characteristics; and we suggest that an additional array of VLF receivers in the southern hemisphere is required to extract the timing of magnetospheric processes from such ground-based observations.