Time domain polarization analysis of Schumann resonance waveforms

Abstract

Schumann resonance waveforms in the lower ELF band are produced by distant lightning discharges. The multiplicity of world-wide thunderstorm centres provides a background spectrum which is generally incoherent. Superimposed on this background are larger amplitude events from individual thunderstorm centres. Source direction finding requires the determination of the polarization properties of these complex and superimposed waveforms. A time domain polarization analysis technique is described and applied to a variety of examples of Schumann resonance waveforms. The background waveforms display the anticipated level of incoherent polarization properties. It is demonstrated that the technique can isolate individual waveforms that are linearly polarized and which represent the arrival of short path signals from single source locations.