Abstract
Atmospheric aerosols significantly impact climate, and the hydrological cycle, in high-altitude regions like the Western Ghats in India, where monsoon dynamics play a critical role. Here we present the first Q-ACSM-based characterization of non-refractory submicron aerosol (NR-PM1) and organic aerosol (OA) source apportionment from Munnar, Kerala, during the Southwest monsoon season (06 June—25 July 2021). The organics comprised the largest fraction of NR-PM1 (42.1 ± 23.7%), closely followed by sulfate (41.0 ± 19.6%). Aerosol composition was strongly controlled by meteorological regime: sulfate dominated during active monsoon periods and exhibited a persistent high-speed W–SW transport signature consistent with strong marine influence, while organics became the dominant fraction (52%) during the mixed period. OA source apportionment, conducted using Positive Matrix Factorization (PMF), identified four key factors: hydrocarbon-like OA (HOA, 11.4 ± 10.4%), biomass-burning OA (BBOA, 14.0 ± 13.8%), Biomass-Burning-derived Oxygenated OA (BB-OOA, 40.2 ± 23.0%), and Oxygenated OA (OOA, 34.3 ± 24.3%), suggesting dominance of secondary aerosols in the region. These findings highlight the contrasting roles of long-range marine transport and local secondary processing in shaping fine aerosol composition at high-altitude monsoon sites, with implications for aerosol hygroscopicity and cloud condensation nuclei activity over the Western Ghats.
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Acknowledgements
S.S.G. gratefully acknowledges partial funding from the Ministry of Earth Sciences (MoES; sanction number MoES/16/04/2017-APHH (PROMOTE)), the Government of India, and the Department of Science and Technology (sanction number DST/CCP/CoE/141/2018C). P.L. acknowledges the start-up funding support from the Georgia Institute of Technology. A.S. acknowledges the Department of Education, Government of India, for the Prime Minister’s Research Fellowship (PMRF) for her doctoral research. S.S.G. gratefully acknowledge the partial financial support from Sharp Business Systems (India) Private Limited for establishing the NABHA Laboratory. The authors acknowledge the valuable support and help provided by the staff at the College of Engineering, Munnar, during the campaign.
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Kalkura, K.N., Singh, A., K. A., R.C. et al. Aerosol interplay with meteorology in a biodiversity-rich high-altitude site in India: impacts of southwest monsoon on aerosol chemical characteristics.
Sci Rep (2026). https://doi.org/10.1038/s41598-026-57287-7
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DOI: https://doi.org/10.1038/s41598-026-57287-7
Keywords
- Aerosol Chemical Composition
- Secondary Organic Aerosol (SOA)
- Positive Matrix Factorization (PMF)
- Southwest Monsoon
- Western Ghats
Source: Ecology - nature.com
