HR: 1340h
AN: A23B-1260    [Abstracts]
TI: Parameterization of the CCN Activity of Organic, Nitrate and Mixed Aerosol During Pollution and Biogenic Episodes at a Rural Field Campaign in Ontario
AU: * Shantz, N C
EM: nshantz@chem.utoronto.ca
AF: University of Toronto, Lash Miller Chemical Laboratories 80 St. George St., Toronto, ON M5S 3H6, Canada
AU: Leaitch, R
EM: Richard.Leaitch@ec.gc.ca
AF: Environment Canada, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada
AU: Abbatt, J
EM: jabbatt@chem.utoronto.ca
AF: University of Toronto, Lash Miller Chemical Laboratories 80 St. George St., Toronto, ON M5S 3H6, Canada
AU: Chang, R
EM: rchang@chem.utoronto.ca
AF: University of Toronto, Lash Miller Chemical Laboratories 80 St. George St., Toronto, ON M5S 3H6, Canada
AU: Slowik, J
EM: jslowik@chem.utoronto.ca
AF: University of Toronto, Lash Miller Chemical Laboratories 80 St. George St., Toronto, ON M5S 3H6, Canada
AU: Toom-Sauntry, D
EM: Desiree.Toom-Sauntry@ec.gc.ca
AF: Environment Canada, 4905 Dufferin St., Toronto, ON M3H 5T4, Canada
AU: Vlasenko, A
EM: avlasenk@chem.utoronto.ca
AF: University of Toronto, Lash Miller Chemical Laboratories 80 St. George St., Toronto, ON M5S 3H6, Canada
AB: An intensive field campaign was conducted at a rural site near Egbert, Ontario, Canada (70 km north of Toronto) in May and June of 2007. Periods of specific interest include: (1) Northwest winds resulting in exceedingly clean air; (2) Northerly winds corresponding with terpene oxidation; and (3) Southerly winds carrying the urban outflow from Toronto. A range of aerosol chemical compositions were measured including organic-rich, nitrate-rich or mixed sulfate/organic aerosol. An objective of the study is to develop a physically accurate understanding of the role of organic aerosol constituents on hygroscopic growth that is sufficiently simple to be included in climate models. Because it can be difficult to characterize the water activity of organic aerosols due to their complexity and the lack of detailed chemical composition information, we determine a single parameter that describes both hygroscopic and cloud condensation nucleus activity (kappa: Petters and Kreidenweis [2007]) for selected air masses. Size-resolved chemical composition measurements, a continuous flow cloud condensation nucleus counter (CCNc) and a static flow CCNc were used to determine kappa values. These kappa values were implemented into a simplified version of a detailed microphysical adiabatic cloud parcel (ACP) model representing the water activity via kappa and tested against the detailed ACP model.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting