AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Forty-Seven Years of MSA Concentrations in the Finnish Arctic
JAMES R. LAING, Philip K. Hopke, Eleanor F. Hopke, Liaquat Husain, Vincent A. Dutkiewicz, Jussi Paatero, Yro Viisinen, Clarkson University
Abstract Number: 52 Working Group: Aerosols, Clouds, and Climate
Abstract MSA (Methane Sulfonate) is a unique organosulfur species that can be used as a marker for these biogenic oceanic sulfur sources. MSA is the oxidation product of DMS (dimethylsulfide), which is excreted by marine planktonic algae and subsequently transported to the air (Bates, 1992). Week-long historical filter samples collected at Kevo, Finland from 1964-2010 have been analyzed for methane sulfonate (MSA) as well as various other species. MSA has a distinct summer maximum during the months of May, June and July associated with warmer waters and increased primary productivity in the surrounding oceans. PSCF (potential source contribution function) analysis was performed using HYSPLIT4 5-day back-trajectories. Results show that source regions for MSA in the summer are primarily in the North Atlantic Ocean, and the Norwegian and Barents Seas. For the peak summer months, the average MSA concentrations decreased from 1964 to the early-1980s, increased from the early 1980s till 2000, and have decreased in the 2000’s. It has been proposed by Charlson et al. (1987, Nature 326, 655-661) that biogenic sulfate is part of a negative feedback mechanism that moderates the climate, where biogenic sulfate form cloud condensation nuclei (CCN). Increased CCN alters the radiative balance of the atmosphere by increasing shortwave radiation albedo, affecting sea surface temperature and the production of DMS by algae. Sea surface temperatures in the northern hemisphere have risen since the early 1970s, most dramatically in the North Atlantic (Thompson, 2010). Using the HadSST2 Dataset (Rayner, 2006, Journal of Climate 19, 446-469), a significant correlation was found between average yearly MSA concentrations for the months of peak concentration (May, June, and July) and yearly SST anomalies in the region from 30W to 80E and 40N to 90N.