Scattered Field Polarization for VLF Remote Sensing of Transient Events

Abstract

Very low frequency (VLF, 3−30 kHz) radio waves can propagate large distances around the globe in the Earthionosphere waveguide and be scattered by transient disturbances to the lower ionosphere. Such scattering enables the VLF remote sensing of lightning-related (as well as other) disturbances to the D-region ionosphere (60−100 km altitude). The polarization of the field scattered by the ionospheric disturbance has not been investigated in detail, primarily because it can be difficult to measure. In this paper, we present a simple, reliable method to accurately calculate the polarization of such a scattered field, and we apply the method to analyze ionospheric VLF scattering events.