Winter Lightning Flashes as Detected by a Lightning Mapping Array (LMA) During the Lake Effect Electrification (LEE) Field Campaign

The Lake Effect Electrification (LEE) Field Campaign, which took place downwind of Lake Ontario during the winter of 2022/2023, observed electric field profiles and lightning during lake-effect snow events. A 16-station lightning mapping array (LMA) was deployed in the Tug Hill Plateau region of New York to provide detailed structure of winter lightning flashes that initiated during the project. Comparisons between LMA-inferred charge regions and charge regions measured by balloon-borne electric field meters launched into the convection show good agreement in charge structure, with a tripolar (positive-negative-positive) storm charge structure in the nearshore environment and positive storm charge above negative storm charge in the inland environment.

LMA-observed lightning flash counts, as provided by an algorithm and manual counting, as well as flash statistics such as flash area, power, energy, duration, and source counts will be presented and compared to statistics observed by the Geostationary Lightning Mapper, the Earth Networks Total Lightning Network, and the National Lightning Detection Network. As expected, many of the flashes observed during the LEE project were close to the ground, interacted with tall, manmade objects such as communication towers and wind turbines, and consisted of only one polarity of channel propagation implying that they propagated through only one storm charge. In these flashes, neutralization of that charge by the lightning channel had an immediate effect and rapidly initiated more discharges where the first group of discharges ended. This led to a chain of discharges initiating in quick succession in a way not often seen in summertime convection. Occasionally, flashes propagated into an upper region of positive storm charge or above radar-indicated cloud top. The flashes observed during the LEE field campaign highlight the difficulties of flash counting and can lend to the discussion of how to define a flash using LMA data.