Why Did the Lightning Mapping Array Miss Flashes During the Lake Effect Electrification Project?

During the Lake Effect Electrification (LEE) project, a 16 sensor Lightning Mapping Array was deployed around the Tug Hill Plateau to capture lightning in the lake-effect snow bands produced east of Lake Ontario. The network performed very well overall, capturing over 200 flashes near and around the plateau throughout the winter season. However, after part of the network had been collected at the end of the season, many more flashes were visually or audibly observed by participants in the field than were recorded by the LMA. In contrast, the detection efficiency model of Chmielewski and Bruning (2016) estimated relatively good network performance over the same region in which the participants observed flashes. We found that the reason for this discrepancy is due to the characteristics of the flashes themselves, which was drastically different from the population of flashes which were used to drive the network performance model. Throughout the project, many of the flashes over the Tug were low in altitude due to the depth of the lake-effect snow band, of limited spatial extent due to the horizontal size of the convective regions within lake-effect snow bands, and appeared to be triggered by and consisted of purely upward positive leaders which emit less very high frequency (VHF) radiation than their negative leader counterparts. We will demonstrate how the network model may be adjusted to handle the population of flashes observed during LEE by limiting the VHF source power distribution and expected number of VHF sources per flash. We will also demonstrate how the sensors nearest to the flashes may capture enhanced VHF emissions, even when the network as a whole is unable to locate the flashes producing it.