Long-term changes in aerosol radiative properties over Ny-Ålesund: Results from Indian scientific expeditions to the Arctic

Continuous long-term monitoring of black carbon (BC) mass concentration and aerosol light scattering coefficient (sigma(SCA)), supplemented by number size distribution and chemical composition, are utilized in this study to understand the temporal changes in aerosol properties, associated source processes and radiative effects at Ny-angstrom lesund (79 degrees N) in the Svalbard Archipelago. A statistically significant decreasing trend in BC (- 24.7 ng m(-3) decade(-1)) is observed during spring of 2010-2019. In contrast, sigma SCA depicted a general increasing trend (5.2 Mm(-1) decade(-1)) during 2011-2016. BC and sigma(SCA) were higher during winter and spring. Aerosol single scattering albedo was highest in May similar to 0.95 (during spring) and lowest in September similar to 0.87 (during summer). Fractional share of BC to total aerosol mass was higher in winter and summer. Anthropogenic SO42- and NO3- (after ssNa(+)) species dominated the summer, when total number and mass concentrations of aerosols were at their minimum. Elemental Carbon (EC) and Organic Carbon (OC) showed higher concentrations in spring with EC-to-OC ratio similar to 0.08 - 0.22. The columnar AOD varied between 0.01 and 0.20 (annual mean similar to 0.09), resulting in aerosol radiative forcing (in the top of the atmosphere) similar to 0.15 - 2.69 Wm(-2) in the month of April (during spring). Potential source contribution function (PSCF) revealed the dominant source areas to be over Europe and Russia in terms of contributing to the seasonal high BC mass concentrations at Ny-angstrom lesund. Our study has also revealed an unusual impact of biomass burning aerosols (advected from the Alaska wildfire) during July 2015.