The Impact of Urban Particulate Matter on Lightning Frequency in Thunderstorms: A Case Study of the Bangkok Metropolitan Region

Abstract Bangkok, Thailand is a tropical Asian megacity with high aerosol concentrations and frequent thunderstorm activity. This investigation examines the covariation between thermodynamics, aerosols, and thunderstorms, using lightning stroke counts as a measure of intensity, for a five-year period (2016–2020). The investigation incorporates data from the aerosol robotic network (AERONET), ERA-5 reanalysis, ground-based air quality stations, and total lighting data from Vaisala Inc.’s GLD360 network to examine the aerosol-thermodynamic interrelationships within thunderstorm initiation environments. Results indicate that aerosol impacts on thunderstorms are robust and, when examined in concert with instability, can augment lightning. Thermodynamic instability is also positively correlated with stroke counts in thunderstorms. Particulate matter greater than 10 µg m -3 (PM10) concentration is significantly higher in thunderstorms containing more than 100 strokes, supporting the potential role of aerosols in promoting the non-inductive charge process. The emergence of a “boomerang” or threshold effect is also evident as aerosol optical depth (AOD) increases. Evidence suggests increasing AOD initially promotes, then limits, instability and thunderstorm intensity. Finally, there exists a positive relationship between aerosol concentration and particle size in thunderstorm initiation environments.