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Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 12779-12795, 2017
https://doi.org/10.5194/acp-17-12779-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
26 Oct 2017
Do contemporary (1980–2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?
Meri M. Ruppel1, Joana Soares2,3, Jean-Charles Gallet4, Elisabeth Isaksson4, Tõnu Martma5, Jonas Svensson1,2, Jack Kohler4, Christina A. Pedersen4, Sirkku Manninen1, Atte Korhola1, and Johan Ström6 1Department of Environmental Sciences, University of Helsinki, Helsinki, 00790, Finland
2Finnish Meteorological Institute (FMI), Helsinki, 00560, Finland
3Air Quality Research Division, Environment and Climate Change Canada, Toronto, M3H 5T4, Canada
4Norwegian Polar Institute, Tromsø, 9296, Norway
5Department of Geology, Tallinn University of Technology, Tallinn, 19086, Estonia
6Department of Environmental Science and Analytical Chemistry ACES (Atmospheric Science Unit), Stockholm University, Stockholm, 11418, Sweden
Abstract. The climate impact of black carbon (BC) is notably amplified in the Arctic by its deposition, which causes albedo decrease and subsequent earlier snow and ice spring melt. To comprehensively assess the climate impact of BC in the Arctic, information on both atmospheric BC concentrations and deposition is essential. Currently, Arctic BC deposition data are very scarce, while atmospheric BC concentrations have been shown to generally decrease since the 1990s. However, a 300-year Svalbard ice core showed a distinct increase in EC (elemental carbon, proxy for BC) deposition from 1970 to 2004 contradicting atmospheric measurements and modelling studies. Here, our objective was to decipher whether this increase has continued in the 21st century and to investigate the drivers of the observed EC deposition trends. For this, a shallow firn core was collected from the same Svalbard glacier, and a regional-to-meso-scale chemical transport model (SILAM) was run from 1980 to 2015. The ice and firn core data indicate peaking EC deposition values at the end of the 1990s and lower values thereafter. The modelled BC deposition results generally support the observed glacier EC variations. However, the ice and firn core results clearly deviate from both measured and modelled atmospheric BC concentration trends, and the modelled BC deposition trend shows variations seemingly independent from BC emission or atmospheric BC concentration trends. Furthermore, according to the model ca. 99 % BC mass is wet-deposited at this Svalbard glacier, indicating that meteorological processes such as precipitation and scavenging efficiency have most likely a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends. BC emission source sectors contribute differently to the modelled atmospheric BC concentrations and BC deposition, which further supports our conclusion that different processes affect atmospheric BC concentration and deposition trends. Consequently, Arctic BC deposition trends should not directly be inferred based on atmospheric BC measurements, and more observational BC deposition data are required to assess the climate impact of BC in Arctic snow.

Citation: Ruppel, M. M., Soares, J., Gallet, J.-C., Isaksson, E., Martma, T., Svensson, J., Kohler, J., Pedersen, C. A., Manninen, S., Korhola, A., and Ström, J.: Do contemporary (1980–2015) emissions determine the elemental carbon deposition trend at Holtedahlfonna glacier, Svalbard?, Atmos. Chem. Phys., 17, 12779-12795, https://doi.org/10.5194/acp-17-12779-2017, 2017.
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Short summary
Black carbon (BC) deposition enhances Arctic warming and melting. We present Svalbard ice core BC data from 2005 to 2015, comparing the results with chemical transport model data. The ice core and modelled BC deposition trends clearly deviate from measured and observed atmospheric concentration trends, and thus meteorological processes such as precipitation and scavenging efficiency seem to have a stronger influence on the BC deposition trend than BC emission or atmospheric concentration trends.
Black carbon (BC) deposition enhances Arctic warming and melting. We present Svalbard ice core...
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