Vertical profile of atmospheric dimethyl sulfide in the Arctic
Spring and Summer
Roghayeh Ghahremaninezhad1, Ann-Lise Norman1, Betty Croft2, Randall V. Martin2, Jeffrey R. Pierce3, Julia Burkart4, Ofelia Rempillo1, Heiko Bozem5, Daniel Kunkel5, Jennie L. Thomas6, Amir A. Aliabadi7, Gregory R. Wentworth4, Maurice Levasseur8, Ralf M. Staebler9, Sangeeta Sharma9, and Richard Leaitch91Department of Physics and Astronomy, University of Calgary, Calgary, Canada 2Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Canada 3Department of Atmospheric Science, Colorado State University, Fort Collins, USA 4Department of Chemistry, University of Toronto, Toronto, Canada 5Institute of Atmospheric Physics, University of Mainz, Mainz, Germany 6Sorbonne Universités, UPMC Univ. Paris 06, Universite Versailles St-Quentin, CNRS/INSU, UMR8190, LATMOS-IPSL, Paris, France 7Environmental Engineering Program, School of Engineering, University of Guelph, Guelph, Canada 8Department of Biology, Laval University, Quebec, Canada 9Environment and Climate Change Canada, Toronto, Canada
Received: 12 Jan 2017 – Accepted for review: 15 Jan 2017 – Discussion started: 16 Jan 2017
Abstract. Vertical distributions of atmospheric dimethyl sulfide (DMS(g)) were sampled aboard the research aircraft Polar 6 near Lancaster Sound, Nunavut, Canada in July 2014 and on pan-Arctic flights in April 2015 that started from Longyearbyen, Spitzbergen, and passed through Alert and Eureka, Nunavut and Inuvik, Northwest Territories. Larger mean DMS(g) mixing ratios were present during April 2015 (campaign-mean of 116±8 pptv) compared to July 2014 (campaign-mean of 20±6 pptv). Observations in July 2014 indicated a decrease in DMS(g) mixing ratios with altitude up to about 3 km, and the largest mixing ratios were found near the surface above ice-edge and open water, coincident with increased particle concentrations. In contrast, DMS(g) mixing ratios sampled in April 2015 were as high as 100 pptv near 2500 m. The April campaign also exhibited uniform campaign-mean vertical profiles overall although some profiles showed an increase with altitude.
GEOS-Chem chemical-transport model simulations indicate that Arctic seawater (north of 66° N) contributes the majority of DMS(g) to the Arctic profiles (>90 %) in July 2014 flight tracks which were below 3000 m. More than 90 % of DMS(g) in April 2015 was from Arctic seawater for measurements below 500 m, but that declined to 60 % for altitudes between 500 m and 3000 m. FLEXPART simulations indicate that for summer 2014, the sampled air mass originated over Baffin Bay and the Canadian Arctic Archipelago. Whereas, for springtime 2015, the air mass sampled on flights near Alert and Eureka originated from Baffin Bay/Canadian Archipelago and from long-range transport (LRT) around the northern tip of Greenland. Our results highlight the role of open water below the flight as the source of DMS(g) during July 2014, and the influence of LRT of DMS(g) from further afield in the Arctic above 2500 m during April 2015.
Ghahremaninezhad, R., Norman, A.-L., Croft, B., Martin, R. V., Pierce, J. R., Burkart, J., Rempillo, O., Bozem, H., Kunkel, D., Thomas, J. L., Aliabadi, A. A., Wentworth, G. R., Levasseur, M., Staebler, R. M., Sharma, S., and Leaitch, R.: Vertical profile of atmospheric dimethyl sulfide in the Arctic
Spring and Summer, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2017-33, in review, 2017.