ACP Atmospheric Chemistry and Physics ACP Atmos. Chem. Phys. 1680-7324 Copernicus Publications Göttingen, Germany 10.5194/acp-13-3825-2013 Pollution transport from North America to Greenland during summer 2008 Thomas J. L. 1 Raut J.-C. https://orcid.org/0000-0002-3552-2437 1 Law K. S. 1 Marelle L. 1 Ancellet G. https://orcid.org/0000-0002-1542-6085 1 Ravetta F. 1 Fast J. D. 2 Pfister G. 3 Emmons L. K. https://orcid.org/0000-0003-2325-6212 3 Diskin G. S. 4 Weinheimer A. 3 Roiger A. 5 Schlager H. 5 UPMC Univ. Paris 06, Université Versailles St-Quentin, CNRS/INSU, UMR8190, LATMOS-IPSL, Paris, France Pacific Northwest National Laboratory, Richland, WA, USA National Center for Atmospheric Research, Boulder, CO, USA NASA Langley Research Center, Hampton, VA, USA Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany 10 04 2013 13 7 3825 3848 Copyright: © 2013 J. L. Thomas et al. 2013 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/articles/13/3825/2013/acp-13-3825-2013.html The full text article is available as a PDF file from https://acp.copernicus.org/articles/13/3825/2013/acp-13-3825-2013.pdf

Ozone pollution transported to the Arctic is a significant concern because of the rapid, enhanced warming in high northern latitudes, which is caused, in part, by short-lived climate forcers, such as ozone. Long-range transport of pollution contributes to background and episodic ozone levels in the Arctic. However, the extent to which plumes are photochemically active during transport, particularly during the summer, is still uncertain. In this study, regional chemical transport model simulations are used to examine photochemical production of ozone in air masses originating from boreal fire and anthropogenic emissions over North America and during their transport toward the Arctic during early July 2008. Model results are evaluated using POLARCAT aircraft data collected over boreal fire source regions in Canada (ARCTAS-B) and several days downwind over Greenland (POLARCAT-France and POLARCAT-GRACE). Model results are generally in good agreement with the observations, except for certain trace gas species over boreal fire regions, in some cases indicating that the fire emissions are too low. Anthropogenic and biomass burning pollution (BB) from North America was rapidly uplifted during transport east and north to Greenland where pollution plumes were observed in the mid- and upper troposphere during POLARCAT. A model sensitivity study shows that CO levels are in better agreement with POLARCAT measurements (fresh and aged fire plumes) upon doubling CO emissions from fires. Analysis of model results, using &Delta;O<sub>3</sub>/&Delta;CO enhancement ratios, shows that pollution plumes formed ozone during transport towards the Arctic. Fresh anthropogenic plumes have average &Delta;O<sub>3</sub>/&Delta;CO enhancement ratios of 0.63 increasing to 0.92 for aged anthropogenic plumes, indicating additional ozone production during aging. Fresh fire plumes are only slightly enhanced in ozone (&Delta;O<sub>3</sub>/&Delta;CO=0.08), but form ozone downwind with &Delta;O<sub>3</sub>/&Delta;CO of 0.49 for aged BB plumes (model-based run). We estimate that aged anthropogenic and BB pollution together made an important contribution to ozone levels with an average contribution for latitudes >55&deg; N of up to 6.5 ppbv (18%) from anthropogenic pollution and 3 ppbv (5.2%) from fire pollution in the model domain in summer 2008.

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