Enhanced Positive Cloud-to-Ground Lightning in Thunderstorms Ingesting Smoke from Fires

Abstract

Smoke from forest fires in southern Mexico was advected into the U.S. southern plains from April to June 1998. Cloud-to-ground lightning (CG) flash data from the National Lightning Detection Network matched against satellite-mapped aerosol plumes imply that thunderstorms forming in smoke-contaminated air masses generated large amounts of lightning with positive polarity (+CGs). During 2 months, nearly half a million flashes in the southern plains exhibited +CG percentages that were triple the climatological norm. The peak currents in these +CGs were double the expected value. These thunderstorms also produced abnormally high numbers of mesospheric optical sprites.