Effect of Climate Forcing Parameters on Coastal Regions Due to Maritime Aerosols

Maritime activities, particularly shipping and port-based activities, are major sources of fine aerosols that shape air quality and regional climate in densely populated coastal zones. This study examines marine aerosol emissions and their radiative impacts along India’s coastline for the decade 2015–2024. Emission inventories from the Directorate General of Shipping (DGS), observations from Continuous Ambient Air Quality Monitoring Stations (CAAQMS), and short-term ship-based sampling near Chennai Port were analyzed. To assess radiative impacts, data were modeled using the OPAC–SBDART framework, and simulations were run to capture spatial and temporal variability in aerosol concentrations and radiative forcing. The results show a steady rise in aerosol levels along the eastern seaboard, with Chennai, Paradip, and Kolkata recording annual averages up to 68 µg/m³ by 2024. Modeled radiative forcing intensified to –1.6 W/m², pointing to stronger atmospheric cooling. Collectively, thirteen major ports accounted for 73.2% of emissions, averaging 168.4 µg/m³, compared with 26.8% from non-port coastal areas, which averaged 61.7 µg/m³. A temporary decline during the COVID-19 lockdown (2020–2021) demonstrated the mitigation potential of reduced shipping activity. Correlations between particulate levels, wind speed, and vessel orientation reaffirmed the localized influence of port operations. These findings underscore the urgency of port-specific mitigation strategies, including cleaner fuels, stricter emission controls, and expanded monitoring networks. The study highlights how shipping and port-based activities, when analyzed through modeled datasets, are reshaping aerosol dynamics and radiative forcing along India’s coast, with significant implications for air quality and climate policy.