The VLF Transmitter Signal as a Diagnostic of Thunderstorm-Ionosphere Coupling

Abstract:

Very Low Frequency (VLF) transmitter remote sensing has evolved into a useful diagnostic for the D-region ionosphere, particularly in the presence of lightning-associated disturbances. All it requires is a VLF radio receiver monitoring the amplitude and/or phase of a beacon signal over time, which perturbs during ionospheric disturbances.

For much of this field’s history, amplitude and phase were analyzed and presented as individual data streams. A clever formulation known as scattered field analysis was recently reintroduced, which combines amplitude and phase into a single measurement, and calculates the phasor of the scattered field, providing insights that would otherwise be missed by either amplitude or phase individually.

In this presentation we describe another useful formulation that goes one step further, combining the amplitude and phase of two horizontal magnetic field channels into a single measurement: polarization ellipse. This allows insights that would otherwise by missed by examining one channel at a time.

Using this formulation, we take a new look at ionospheric disturbances from thunderstorms, including early/fast events and lightning-induced electron precipitation.