HR: 16:15h
AN: A34A-02 INVITED    [Abstracts]
TI: Aerosol Physiochemistry in Clean and Polluted Regions: Influences on Optical Properties and CCN
AU: * Clarke, A
EM: tclarke@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: kapustin, V
EM: kapustin@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: Howell, S
EM: showell@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: Shinozuka, Y
EM: yohei@hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: McNaughton, C
EM: cameronm@soest.hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: Zhou, J
EM: jczhou@hawaii.edu
AF: Department of Oceanography, University of Hawaii, 1000 Pope Rd., Honolulu, HI 96822, United States
AU: DeCarlo, P
EM: decarlop@colorado.edu
AF: Dept. of Chemistry & CIRES, UCB 216, Boulder, CO 80309, United States
AU: Jimenez, J
EM: jose.jimenez@colorado.edu
AF: Dept. of Chemistry & CIRES, UCB 216, Boulder, CO 80309, United States
AU: Roberts, G
EM: gcroberts@ucsd.edu
AF: Scripps Institution of Oceanography, UCSD, 9500 Gilman Drive, La Jolla, CA 92093, United States
AB: Long range transport of aerosol from urban regions and anthropogenic sources is recognized to influence the radiative properties of aerosol and cloud condensation nuclei, CCN, over large portions of the planet. The nature of these influences is determined by the size distributions, concentration and composition of the aerosol and their magnitude relative to natural sources. We have participated in diverse major field studies over the past decade designed to measure and isolate key properties that can be used to characterize various source regions and to provide aerosol parameters to effectively model both "direct" and "indirect" radiative effects. More recently these have expanded to include scales that can assess transformation in both gas and aerosol components as they evolve downwind or get lofted into the free troposphere. These experiments have revealed the importance of primary emissions and secondary emissions and the state of mixing of the aerosol both near the source and after aging downwind. The physiochemical processes that influence aerosol composition, growth, evolution, optical properties and cloud processes differ markedly with size. In this talk we focus on direct radiative effects that depend on sizes that dominate aerosol surface area or mass and on cloud related effects more sensitive to smaller sizes that dominate aerosol number and CCN. Key players of both anthropogenic and natural origin are black carbon (BC), sulfate, nitrate and organic carbon. These frequently evolve into internal mixtures and/or interact with similar natural aerosol such as dust and sea- salt. Hence, the size resolved state-of-mixing of these components determine their influences and also impact the strategies that might be used to mitigate any effects. Recent data highlight the significance of BC to both direct and indirect effects and reveal its multiple roles expressed through its optical properties, its evolution, its relation to light absorbing OC (brown carbon) and role as a condensation sites for other aerosol. Observed variations in mixing state for diverse regions and/or combustion sources also affect other aerosol properties including the humidity dependence of light scattering expressed as f(RH) or gamma. Such aging can vary the mixing ratio of OC in the aerosol which modifies their effectiveness as CCN at a given size. Observations of particle nucleation and growth are now common but its larger significance will depends upon the particle number, relative to primary emissions, that can age and survive to optically effective sizes or CCN. The latter is particularly complex as cloud are sinks, sources and processors of both aerosol and gases that impact the CCN population. A related issue we address is how well satellite retrieval of aerosol radiances can be used to monitor relevant properties such as PM2.5 or the potential to retrieve effective CCN. Examples of these and other size resolved properties revealed in recent campaigns will be presented.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0321 Cloud/radiation interaction
DE: 0322 Constituent sources and sinks
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting