Extreme Middle Eastern dust event over metropolitan Mumbai, India, associated with enhanced lightning activity

This study examines the influence of transboundary dust on lightning activity in the Mumbai region, India, during an extreme pre-monsoon event on May 13, 2024, which resulted in multiple fatalities and injuries. A severe dust intrusion from the Middle East and Arabian deserts coincided with a westward-moving convective system originating from inland Nashik, India, and moving toward the southwestern coast of India. A multi-platform dataset combining ground-based and satellite observations was used. Lightning data obtained from the Indian Lightning Location Network (ILLN), PM₁₀ concentrations from the Central Pollution Control Board (CPCB), cloud parameters from satellite and reanalysis, and dust transport pathways from HYSPLIT. Results show that transboundary dust led to an eightfold increase in PM₁₀ (~800 µg m⁻3), accompanied by more than 31,000 lightning flashes, with a peak of over 8,717 flashes coinciding with the PM₁₀ peak at 16:00 IST. Dust particles altered cloud microphysics by reducing cloud liquid water and enhancing cloud ice water content. This process strengthened deep convection, lowered cloud-top temperatures to ~205K, and elevated cloud tops to ~15-16km. These conditions promote strong non-inductive charge separation, resulting in intense lightning over metropolitan Mumbai. The findings provide robust evidence that long-range transported dust significantly enhances thunderstorm electrification by promoting ice microphysics and increasing lightning activity.