A34F-07
Water Soluble Ions in Bulk Aerosol During the WINTER 2015 Campaign.
Wednesday, 16 December 2015: 17:30
3010 (Moscone West)
Jack E Dibb1, Eric M Scheuer1, Steven S Brown2, Pedro Campuzano Jost3, Dorothy L Fibiger4, Hongyu Guo5, Jose L Jimenez6, Felipe Lopez-Hilfiker7, Erin E. McDuffie8, Jason Clay Schroder9, Amy Sullivan10, Joel A Thornton11, Patrick R Veres2 and Rodney J Weber5, (1)University of New Hampshire Main Campus, Durham, NH, United States, (2)NOAA Boulder, Boulder, CO, United States, (3)university of Colorado, Chemistry and Biochemistry, Boulder, CO, United States, (4)National Science Foundation, Atmospheric and Geospace Sciences Postdoctoral Fellow, Arlington, VA, United States, (5)Georgia Institute of Technology Main Campus, Earth and Atmospheric Sciences, Atlanta, GA, United States, (6)University of Colorado at Boulder, Dept. of Chemistry and Biochemistry, Boulder, CO, United States, (7)University of Washington Seattle Campus, Seattle, WA, United States, (8)University of Colorado at Boulder, Boulder, CO, United States, (9)Cooperative Institute for Research in Environmental Sciences, Boulder, CO, United States, (10)Colorado State University, Fort Collins, CO, United States, (11)Univ Washington - Seattle, Seattle, WA, United States
Abstract:
Aerosol samples were collected on filters from the NCAR C-130 during the WINTER campaign using an inlet believed to transmit particles up to 4 micron in diameter. Filter integration times were nominally 7 minutes. Aqueous extracts of the filter samples were analyzed by ion chromatography for 5 anions and 5 cations, we focus primarily on chloride and nitrate due to their roles coupling chlorine and nitrogen oxide chemistry. Comparison to measurements of submicron aerosol (by PILS and AMS) indicates that there was significant coarse chloride in the boundary layer on all WINTER flights, including the 7 flights over the continent. Significant super micron chloride at altitudes above 2 km was seen in just 3 of the filter samples from the entire mission, all of these were well inland. During the 6 flights over the Atlantic ocean we observed displacement of chloride from the dominant seasalt aerosol at times, but evidence for coarse mode nitrate or sulfate aerosol to explain this is less clear. While coarse aerosol chloride mixing ratios were sufficient to support observed production of nitryl chloride, no correlations between these compounds were observed on any flights. However, nitrate was positively correlated with nitryl chloride, as expected, on all flights when the latter exceeded several 100’s of pptv for extended periods. Aerosol nitrate was also positively correlated with dinitrogen pentoxide when mixing ratios of the latter exceeded ~500 pptv for significant portions of a flight. On the WINTER flights in February aerosol nitrate was often more abundant than nitric acid, this was less often the case for the flights in March. This change in partitioning of nitrate between gas and particle phases reflects an increasing trend of nitric acid and a small decrease in abundance of aerosol nitrate through the campaign.
