Determinant Role of Aerosols From Industrial Sources in Hurricane Harvey's Catastrophe.

The destructive power of tropical cyclones is driven by latent heat released from water condensation and is inevitably linked to the abundance of aerosols as cloud condensation nuclei. However, the aerosol effects are unaccounted for in most operational hurricane forecast models. We combined multisource measurements and cloud‐resolving model simulations to show fundamentally altered cloud microphysical and thermodynamic processes by anthropogenic aerosols during Hurricane Harvey. Our observational analyses reveal intense lightning and precipitation in the proximity of Houston industrial areas, and these hot spots exhibit a striking geographic similarity to a climatological maximum of lightning flash density in the south‐central United States. Our ensemble cloud‐resolving simulations of Hurricane Harvey indicate that aerosols increase precipitation and lightning by a factor of 2 in the Houston urban area, unraveling the key anthropogenic factor in regulating flooding during this weather extreme. Plain Language Summary: The catastrophic flooding during Hurricane Harvey has received major attention, but the cause remains mysterious. The destructive power of tropical cyclones is produced by the latent heat release from phase change of water, which is linked to airborne particles emitted from vehicles and petrochemical plants. By combining observation and model simulations, our work provides microphysical and thermodynamic insights into the cause of the catastrophic flooding during Hurricane Harvey by the aerosols from industrial sources. Our discovery underscores the importance of representing the effects of anthropogenic aerosols for accurate short‐term forecast and climate projection of tropical cyclones to minimize future catastrophic destruction along the highly industrialized Gulf of Mexico region. Key Points: Aerosol increases accumulative precipitation by a factor of 2T and invigorates lightning activities in Houston during Hurricane HarveyObservations show intense lightning over Houston which exhibits geographic similarity to climatological maximum lightning flash densityTo better forecast extreme weather events, it is essential to account for aerosol effects in operational weather forecast models [ABSTRACT FROM AUTHOR]