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Jim Smith DOE Joint Meeting 2 October, 2009. Nucleation and CCN 2009 Study Atlanta, GA 15 July – 31 August, 2009. Freshly Nucleated Particles are Hygroscopic and can Serve as CCN: Tecamac, Mexico (16 March, 2006). Lance, Smith, Nenes, McMurry et al, unpublished 2009.
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Jim SmithDOE Joint Meeting2 October, 2009 Nucleation and CCN 2009 Study Atlanta, GA 15 July – 31 August, 2009
Freshly Nucleated Particles are Hygroscopic and can Serve as CCN: Tecamac, Mexico (16 March, 2006) Lance, Smith, Nenes, McMurry et al, unpublished 2009
The motivation for NCCN-09 is to understand… Processes that contribute to High Nucleation Rates Processes that contribute to High Growth Rates Impacts of these processes on CCN concentrations.
Participants and their instruments • NCAR • Fred Eisele (neutral molecular clusters, using cluster-CIMS) • Jim Smith (nanoparticle chemical composition) • University of Minnesota • Peter McMurry (>1.5 nm aerosol size distr., hygroscopicity, volatility) • Georgia Tech • Thanos Nenes (size-resolved CCN) • Augsburg College • Dave Hanson (w. Greg Huey, gas-phase amines) • Funding • DOE Atmospheric Sciences Program • NSF NIRT Program
July 25, 2009: Size distribution and sulfuric acid clusters 1000 100 Diameter (nm) 10 3
July 25, 2009: Nanoparticle size distributions 10 149 8 91 DEG 6 55 5 34 4 dN(raw)(cm-3) Diameter (nm) 21 3 13 2 8 5 3 1 149 100 80 91 NPG 60 55 50 34 40 dN(raw)(cm-3) Diameter (nm) 21 30 13 20 8 5 10 3 16:00 8:00 24:00 0:00 4:00 12:00 20:00 Local Standard Time
July 25, 2009: Composition of 20nm particles Negative ions Positive ions
What can observations tell us about the potential impact of new particle formation on CCN populations? loss production • Aerosol general dynamic equation (GDE) solved along diameter trajectory, constrained by measured growth rates and size distributions, to evaluate probability that freshly nucleated 3 nm particle will grow to 100 nm: Scavenging loss Coagulation production Kuang et al., GRL36:L09822, 2009
CCN formation probability & effect of new particle formation on CCN concentrations 1 – 10% of 3 nm particles grow to 100 nm Pre-existing CCN conc. enhanced by 2 – 9x Measured GR: 5 – 22 nm/h (~10x than GRH2SO4) Enhancement in CCN Number Concentrations due to NPF Kuang et al., GRL36:L09822, 2009