Lightning Enhancement in Moist Convection With Smoke‐Laden Air Advected From Australian Wildfires

Abstract

The 2019–2020 Australian wildfire crisis broke the historical bushfire record and heavily contaminated the continental and offshore atmosphere. This study found that lightning strokes increase considerably, by 73% over land and 270% over ocean, during the wildfire season. Thermodynamic parameters support a weaker forcing, unfavorable for frequent lightning activity over ocean. Clear augmentation of smaller cloud ice particles is identified with aerosol, while cloud liquid water path changes are feeble over ocean. Added aerosol invigorates positive intra-cloud (IC) strokes and negative cloud-to-ground (CG) strokes in moist oceanic convection and facilitates a noticeable positive correlation between precipitation and lightning strokes. Rainfall events accompanied by lightning increase by 240% with added aerosol. Aerosol advected from land to ocean can lead to a larger hydrometeor concentration and smaller-size ice crystals above the freezing level and thereby, invigorate convective strength systematically to stimulate more frequent and more robust mixed-phase development, energizing the lightning discharge process.