Summer monsoon raindrop size distributions between polluted and non-polluted rainy days observed over Rourkela, India

Air pollution is one of the significant contributors in changing climate and can change precipitation patterns and weather systems globally through warming or cooling effects. The changing precipitation patterns are significant for developing countries like India, where the pollution levels are high, and monsoon precipitation holds a considerable share of total rainfall. Over eastern India, one of the country's pollution hotspots, the air pollution and precipitation interaction has not been clearly understood. The present work aims to understand the impact of air pollution on precipitation and its microphysical processes during the monsoon season over a tropical eastern India site, Rourkela. The present study utilized in-situ disdrometer data to evaluate the raindrop size distribution characteristics for the monsoon season of 2018-2021. Based on the Air Quality Index (AQI), monsoon rainy days are divided into polluted and non-polluted days. Along with the disdrometer and air quality measurements, the present study used ERA5 reanalysis data to explore the convective indices and vertical profiles of weather variables during polluted and non-polluted days. The results showed that the polluted days had more medium and large-size raindrops, a high mass-weighted mean diameter, high convective available potential energy, and high water vapor compared to non-polluted days.