The influence of aerosols on lightning activity in the Pearl River Delta of China

Investigating the interaction mechanisms between aerosols and lightning activity is a critical scientific issue in understanding the coupling of urban atmospheric environments with regional weather, holding significant value for extreme weather warnings and climate change adaptation. However, recent studies rarely explain the mechanisms of aerosol impacts on lightning activity from the perspective of atmospheric vertical structure. To address this gap, this study conducted an integrated analysis of multi-source observational data (aerosols, cloud-to-ground (CG) lightning, atmospheric thermodynamic factors, and cloud-related parameters) in the Pearl River Delta (PRD) over nine years (2013–2021). It was found that regions with high aerosol loads in the PRD exhibit a strong spatio-temporal correlation with areas of intense lightning activity. If aerosol influences are considered, the convective available potential energy (CAPE) can better account for the variations in lightning activity peaks during specific years. At the same time, strong convective conditions accelerate the shift of aerosols from enhancing to suppressing lightning activity. From the perspective of atmospheric vertical structure, as conditions transition from clean to polluted, the aerosol-cloud interaction (ACI) mechanism significantly increases cloud particle density by up to 300 %. This not only facilitates the electrification process of thunderclouds but also affects the atmospheric temperature gradient at corresponding altitudes. In polluted conditions (with aerosol optical depth (AOD) > 0.75), the temperature gradient in the middle and upper troposphere decreases by more than 0.5 °C. This enhances the development of inversion layers, thereby increasing atmospheric stability and suppressing convection and subsequent lightning activity. The above findings demonstrate that the promoting and inhibiting effects of aerosols on lightning differ under clean and polluted conditions. • Pearl River Delta lightning activity strongly linked to aerosol optical depth spatiotemporal changes. • Aerosols indirectly alter the temperature gradient in the middle and upper layers of the troposphere. • The regulation of lightning activity by aerosols is influenced by thermodynamic factors.