Abstract:

Abstract Pyrocumulonimbus (pyroCb) is a form of deep convection that is generated by the heating from large wildfires and specific meteorology known for producing lightning. We study the lightning characteristics of five pyroCb events in British Columbia, Canada, from June 29 to July 1 of 2021, and compare them to other clean and smoke-filled high-based thunderstorms in the same region and season using ground-based lightning detection data, satellite retrievals, meteorological and atmospheric composition reanalysis, and observed thermodynamic profiles. One large pyroCb event over the Sparks Lake fire that generated persistent overshooting tops had a remarkable amount of lightning activity, with 5,600 total lightning strikes, while the rest of the pyroCb events corresponded with lower injection altitudes and minimal to no observed lightning activity. The cloud-to-cloud (CC) to cloud-to-ground (CG) lightning ratio (CC:CG) in this Sparks Lake pyroCb was significantly higher than in other high-based storms but displayed similar lightning density and slightly lower peak current distributions. All clean and smoke-filled thunderstorms produced significant levels of lightning activity, regardless of their cloud-top altitudes. However, ingestion of smoke significantly reduced the percentage of positive polarity CG strikes when compared to clean cases. These results set a reference for identifying the characteristics of pyrogenic lightning and improved predictions of lightning-caused fire ignitions, which will aid in understanding pyroCb activity and related impacts.

Notes:

e2024JD042285 2024JD042285

Website