FY 2002

A 3-year record of simultaneously measured aerosol chemical and optical properties at Barrow, Alaska

Quinn, P.K., T.L. Miller, T.S. Bates, J.A. Ogren, E. Andrews, and G.E. Shaw

J. Geophys. Res., 107(D11), doi: 10.1029/2001JD001248 (2002)

Results are presented from 3 years of simultaneous measurements of aerosol chemical composition and light scattering and absorption at Barrow, Alaska. All results are reported at the measurement relative humidity of 40%. Reported are the annual cycles of the concentration of aerosol mass, sea salt, non-sea-salt (nss) sulfate, methanesulfonate or MSA^-, NH₄⁺, and nss K⁺, Mg⁺², and Ca⁺² for the submicron and supermicron size ranges. Submicron nss SO₄⁼, NH₄⁺, and nss K⁺, Mg⁺², and Ca⁺² peak in winter and early spring corresponding to the arrival and persistence of Arctic Haze. Submicron sea salt displays a similar annual cycle presumably due to long-range transport from the northern Pacific Ocean. Supermicron sea salt peaks in summer corresponding to a decrease in sea ice extent. Submicron and supermicron MSA^- peak in the summer due to a seasonal increase in the flux of dimethylsulfide from the ocean to the atmosphere. A correlation of MSA^- and particle number concentrations suggests that summertime particle production is associated with this biogenic sulfur. Mass fractions of the dominant chemical species were calculated from the concentrations of aerosol mass and chemical species. For the submicron size range the ionic mass and associated water make up 80 to 90% of the aerosol mass from November to May. Of this ionic mass, sea salt and nss SO₄⁼ are the dominant species. The residual mass fraction, or fraction of mass that is chemically unanalyzed, is equivalent to the ionic mass fraction in June through October. For the supermicron size range the ionic mass and associated water make up 60 to 80% of the aerosol mass throughout the year with sea salt being the dominant species. Also reported for the submicron size range are the annual cycles of aerosol light scattering and absorption at 550 nm,