HR: 0800h
AN: A31B-0840    [Abstracts]
TI: Arctic Biogenic Aerosol Sulphate Using Isotope Apportionment Techniques: 1993-2003
AU: * Norman, A
EM: annlisen@phas.ucalgary.ca
AF: The University of Calgary, Physics & Astronomy 2500 University Dr. N.W., Calgary, AB T2N 1N4 Canada
AU: Sanusi, A
EM: sanusi@phas.ucalgary.ca
AF: The University of Calgary, Physics & Astronomy 2500 University Dr. N.W., Calgary, AB T2N 1N4 Canada
AU: Toom-Sauntry, D
EM: Desiree.Toom-Sauntry@ec.gc.ca
AF: Meteorological Service of Canada, 4905 Dufferin Street , Toronto, ON M3H 5T4 Canada
AU: Gong, S
EM: Sunling.Gong@ec.gc.ca
AF: Meteorological Service of Canada, 4905 Dufferin Street , Toronto, ON M3H 5T4 Canada
AU: Barrie, L
EM: Lbarrie@wmo.int
AF: World Meteorological Organisation, 7 bis, Avenue de la Paix 1211, Geneva, 2 BP2300 Switzerland
AB: Biogenic sulphate is an oxidation product of dimethylsulphide (DMS), a gas released from the ocean surface and an indicator of phytoplankton productivity and/or the extent of open leads in the Arctic. Newly formed CCN from biogenic DMS are postulated, in the CLAW hypothesis, to play a significant role in the global radiation budget by scattering incoming solar radiation and enhancing cloud albedo. The natural abundance sulphur isotope ratio for biogenic sulphate is distinct with respect to anthropogenic and volcanogenic sulphate in the Arctic and can be used to find the proportion and amount of aerosol sulphate from DMS oxidation. Isotope measurements for aerosol sulphate from weekly filter samples collected at Alert, Nunavut, Canada, from 1993-2003 are presented. Isotope mass balance provides a measure of the proportion of biogenic sulphate in these aerosols and the results are compared to the concentration of an alternate DMS oxidation product, methanesulphonic acid (MSA). In contrast to declining anthropogenic sulphate, biogenic sulphate concentrations have increased over the decade examined. Changes in springtime and autumn DMS sulphate concentrations are most apparent and may reflect large scale shifts in open lead formation and closure as well as biogenic productivity in the Arctic.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0321 Cloud/radiation interaction
DE: 0322 Constituent sources and sinks
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005