Spatiotemporal variability of elemental and organic carbon in Svalbard snow during 2007–2018
Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplify Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their...
| Main Authors: | , , , , , , , , , , , , |
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| Format: | Text |
| Language: | English |
| Published: |
2020
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| Subjects: | |
| Online Access: | https://doi.org/10.5194/acp-2020-491 https://www.atmos-chem-phys-discuss.net/acp-2020-491/ |
| Summary: | Light-absorbing carbonaceous aerosols emitted by biomass or fossil fuel combustion can contribute to amplify Arctic climate warming by lowering the albedo of snow. The Svalbard archipelago, being near to Europe and Russia, is particularly affected by these pollutants, and improved knowledge of their distribution in snow is needed to assess their impact. Here we present and synthesize new data obtained on Svalbard between 2007 and 2018, comprising 324 measurements of elemental (EC) and organic carbon (OC) in snow from 49 sites. We used these data, combined with meteorological and aerosol data and snowpack modelling, to investigate the variability of EC and OC deposition in Svalbard snow across latitude, longitude, elevation and time. Overall, EC concentrations ( C snow EC ) ranged from < 1.0 to 266.6 ng g −1 , while OC concentrations ( C snow OC ) ranged from < 1.0 to 9449.1 ng g −1 , with the highest values observed near Ny-Ålesund. Calculated snowpack loadings ( L snow EC , L snow OC ) in April 2016 were 0.1 to 16.2 mg m −2 and 1.7 to 320.1 mg m −2 , respectively. The median C snow EC and L snow EC in the late 2015‒16 winter snowpack on glaciers were close to or lower than those found in earlier (2007–09), comparable surveys. Both L snow EC and L snow OC C increased exponentially with elevation and snow accumulation, with dry deposition likely playing a minor role. Estimated area-averaged snowpack loads across Svalbard were 1.8 mg EC m −2 and 71.5 mg OC m −2 in April 2016. An ~ 11-year long dataset of spring surface snow measurements from central Brøgger Peninsula was used to quantify the interannual variability of EC and OC deposition in snow. On average, C snow EC and C snow OC at Ny-Ålesund (50 m a.s.l.) were 3 and 7 times higher, respectively, than on the nearby Austre Brøggerbreen glacier (456 m a.s.l.), and the median EC/OC in Ny-Ålesund was 6 times higher, pointing to some local EC emission from Ny-Ålesund. While no long-term trends between 2011 and 2018 were found, C snow EC and C snow OC showed synchronous variations at Ny-Ålesund and Austre Brøggerbreen. Comparing C snow EC at Austre Brøggerbreen with aerosol data from Zeppelin Observatory, we found that snowfall washout ratios between 10 and 300 predict a range of C snow EC in agreement with that measured in surface snow. Together, results from this study and comparable surveys confirm the existence of a longitudinal gradient in EC deposition across the Arctic and sub-Arctic, with the lowest C snow EC found in the western Arctic (Alaska, Yukon) and central Greenland, and the highest in northwestern Russia and Siberia. |
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