HR: 13:55h
AN: A13E-02    [Abstracts]
TI: A closure study of aerosol-CCN measurements from recent field campaigns.
AU: * Cubison, M J
EM: michael.cubison@colorado.edu
AF: CIRES, University of Colorado, CIRES Building Room 318 UCB 216, Boulder, CO 80309 United States
AU: Ervens, B
EM: Barbara.Ervens@noaa.gov
AF: Colorado State University and NOAA ETL, 325 Broadway, Boulder, CO 80305 United States
AU: Andrews, B
EM: betsy.andrews@noaa.gov
AF: NOAA CMDL, 325 Broadway, Boulder, CO 80305 United States
AU: DeCarlo, P
EM: peter.decarlo@colorado.edu
AF: CIRES, University of Colorado, CIRES Building Room 318 UCB 216, Boulder, CO 80309 United States
AU: Jobson, T
EM: Tom.Jobson@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Laskin, A
EM: alexander.laskin@pnl.gov
AF: Pacific Northwest National Laboratory, PO Box 999, Richland, WA 99352 United States
AU: Feingold, G
EM: graham.feingold@noaa.gov
AF: NOAA ETL, 325 Broadway, Boulder, CO 80305 United States
AU: Jimenez, J L
EM: jose.jimenez@colorado.edu
AF: Dept of Chemistry and CIRES, University of Colorado, CIRES Building Room 318 UCB 216, Boulder, CO 80309 United States
AU: Ogren, J A
EM: john.a.ogren@noaa.gov
AF: NOAA CMDL, 325 Broadway, Boulder, CO 80305 United States
AB: Aerosols and clouds play an important role in the radiative budget of the atmosphere, through both direct scattering effects and indirectly through perturbations arising from the activation of aerosol to cloud condensation nuclei (CCN). Current understanding of these processes is low (IPCC, 2001), and further understanding of the physical and chemical parameters influencing CCN activation is required to predict these effects in global climate models. We present an investigation into the activation of aerosol to CCN using results from field campaigns in both marine and urban environments. A model simulating the uptake of water vapour to aerosol particles was employed to achieve closure between aerosol composition, size distribution and scattering behaviour, by adjusting the model aerosol composition until calculated physical aerosol parameters match those in the measurements. Results are presented from this model using data from the 2004 ICARTT campaign at Chebogue Point, Nova Scotia. It was shown that closure was quite successful at high supersaturations (> 0.3%), but remained difficult to achieve at the lower supersaturation values. We present findings examining the limitations of the data set and show how the closure was limited through errors in the CCN measurements, low signal to noise in the composition measurements from the Aerodyne Aerosol Mass Spectrometer (AMS), and lack of information about the Aitken or coarse modes. Improvements to the model and data measurement and analysis techniques arising from the Chebogue Point closure study are discussed, and first results are presented using new data taken in summer 2005 from the marine MACE study at Point Reyes, CA, and the urban pollution SOAR campaign in Riverside, CA. We conclude by using the water uptake model to look at the physical and chemical properties influencing CCN activation in the different environments studied.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0321 Cloud/radiation interaction
DE: 3311 Clouds and aerosols
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005