Using the World Wide Lightning Location Network (WWLLN) to Study Very Low Frequency Transmission in the Earth-Ionosphere Waveguide: 2. Model Test by Patterns of Detection/Non-Detection

This is the second half of a two-part study. In the first part, we had used the World Wide Lightning Location Network's (WWLN) recorded signal amplitudes to test a model of Very Low Frequency signal transmission from the lightning to each sensor. The model predicts a dramatic worsening of transmission at low magnetic latitudes, for nighttime propagation (compared to daytime propagation) toward magnetic West. However, we found that the use of amplitudes was ill-adapted for testing the model under conditions of a deep outage of transmission. Since the relative weakening of nighttime transmission is rather counter-intuitive, we have now developed an alternative approach to testing that model prediction. This alternative approach highlights the patterns of detection/non-detection of several low-magnetic-latitude WWLLN stations and compares those patterns with the appropriate patterns of the model transmission.