Cloud forming potential of secondary organic aerosol under near atmospheric conditions

Cloud droplets form by nucleation on atmospheric aerosol particles. Populations of such particles invariably contain organic material, a major source of which is thought to be condensation of photo‐oxidation products of biogenic volatile organic compounds (VOCs). We demonstrate that smog chamber studies of the formation of such biogenic secondary organic aerosol (SOA) formed during photo‐oxidation must be conducted at near atmospheric concentrations to yield atmospherically representative particle composition, hygroscopicity and cloud‐forming potential. Under these conditions, the hygroscopicity measured at 95% relative humidity can be used reliably to predict the CCN activity of the SOA particles by assuming droplet surface tension of pure water. We also show that the supersaturation required to activate a given size of particle decreases with age.

[1]  Ernest Weingartner,et al.  Laboratory observation of oligomers in the aerosol from isoprene/NOx photooxidation , 2006 .

[2]  A. Nenes,et al.  A Continuous-Flow Streamwise Thermal-Gradient CCN Chamber for Atmospheric Measurements , 2005 .

[3]  M Gysel,et al.  Hygroscopicity of aerosol particles at low temperatures. 1. New low-temperature H-TDMA instrument: setup and first applications. , 2002, Environmental science & technology.

[4]  Hugh Coe,et al.  A curved multi-component aerosol hygroscopicity model framework: Part 2 - Including organic compounds , 2005 .

[5]  A. Laaksonen,et al.  Atmospheric Chemistry and Physics The role of surfactants in Köhler theory reconsidered , 2004 .

[6]  Ernest Weingartner,et al.  Secondary organic aerosol formation by irradiation of 1,3,5-trimethylbenzene-NOx-H2O in a new reaction chamber for atmospheric chemistry and physics. , 2005, Environmental science & technology.

[7]  Allen L Robinson,et al.  Rethinking Organic Aerosols: Semivolatile Emissions and Photochemical Aging , 2007, Science.

[8]  Hugh Coe,et al.  A curved multi-component aerosol hygroscopicity model framework: Part 1 Inorganic compounds , 2005 .

[9]  Sonia M. Kreidenweis,et al.  Water activity and activation diameters from hygroscopicity data - Part I: Theory and application to inorganic salts , 2005 .

[10]  John H Seinfeld,et al.  Secondary organic aerosol formation from isoprene photooxidation. , 2005, Environmental science & technology.

[11]  Maria Cristina Facchini,et al.  The effect of physical and chemical aerosol properties on warm cloud droplet activation , 2005 .

[12]  Charles E. Kolb,et al.  A Numerical Characterization of Particle Beam Collimation by an Aerodynamic Lens-Nozzle System: Part I. An Individual Lens or Nozzle , 2002 .

[13]  Kenneth A. Smith,et al.  Development of an Aerosol Mass Spectrometer for Size and Composition Analysis of Submicron Particles , 2000 .

[14]  A. Laaksonen,et al.  The role of surfactants in K ¨ ohler theory reconsidered , 2004 .

[15]  N. Takegawa,et al.  Relationship between hygroscopicity and cloud condensation nuclei activity for urban aerosols in Tokyo , 2006 .

[16]  R Zenobi,et al.  Secondary organic aerosols from anthropogenic and biogenic precursors. , 2005, Faraday discussions.

[17]  M. Petters,et al.  A single parameter representation of hygroscopic growth and cloud condensation nucleus activity , 2006 .

[18]  J. Jimenez,et al.  A generalised method for the extraction of chemically resolved mass spectra from aerodyne aerosol mass spectrometer data , 2004 .

[19]  J. S. Rowlinson,et al.  Molecular Thermodynamics of Fluid-Phase Equilibria , 1969 .

[20]  U. Baltensperger,et al.  Hygroscopicity of aerosol particles at low temperatures. 2. Theoretical and experimental hygroscopic properties of laboratory generated aerosols. , 2002, Environmental science & technology.

[21]  John H. Seinfeld,et al.  Cloud condensation nucleus activation properties of biogenic secondary organic aerosol , 2005 .

[22]  John H. Seinfeld,et al.  Hygroscopicity of secondary organic aerosols formed by oxidation of cycloalkenes, monoterpenes, sesquiterpenes, and related compounds , 2006 .

[23]  Martin Gysel,et al.  Hygroscopic properties of water-soluble matter and humic-like organics in atmospheric fine aerosol , 2003 .

[24]  Yinon Rudich,et al.  under a Creative Commons License. Atmospheric Chemistry and Physics Cloud Condensation Nuclei properties of model and atmospheric , 2006 .

[25]  Sonia M. Kreidenweis,et al.  Influence of water‐soluble organic carbon on cloud drop number concentration , 2005 .

[26]  Erik Swietlicki,et al.  Organic aerosol and global climate modelling: a review , 2004 .

[27]  Sonia M. Kreidenweis,et al.  Cloud droplet activation of secondary organic aerosol , 2007 .

[28]  P. Mcmurry,et al.  Estimation of water uptake by organic compounds in submicron aerosols measured during the Southeastern Aerosol and Visibility Study , 2000 .

[29]  R. Robinson,et al.  Interactions in Aqueous Nonelectrolyte Solutions. I. Solute-Solvent Equilibria , 1966 .

[30]  Martin Gallagher,et al.  2. Measurements of fine particulate chemical composition in two U.K. cities , 2003 .

[31]  Alfred Wiedensohler,et al.  Hygroscopic growth and measured and modeled critical super‐saturations of an atmospheric HULIS sample , 2007 .

[32]  Edward Charles Fortner,et al.  Atmospheric New Particle Formation Enhanced by Organic Acids , 2004, Science.

[33]  Riikka Sorjamaa,et al.  The influence of surfactant properties on critical supersaturations of cloud condensation nuclei , 2006 .

[34]  Charles E. Kolb,et al.  Ambient aerosol sampling using the Aerodyne Aerosol Mass Spectrometer , 2003 .

[35]  M. Andreae,et al.  Size Matters More Than Chemistry for Cloud-Nucleating Ability of Aerosol Particles , 2006, Science.

[36]  J. Seinfeld,et al.  Gas/Particle Partitioning and Secondary Organic Aerosol Yields , 1996 .

[37]  Hugh Coe,et al.  Simplification of the representation of the organic component of atmospheric particulates. , 2005, Faraday discussions.

[38]  Arthur Garforth,et al.  A mass spectrometric study of secondary organic aerosols formed from the photooxidation of anthropogenic and biogenic precursors in a reaction chamber , 2006 .

[39]  M. Facchini,et al.  Cloud albedo enhancement by surface-active organic solutes in growing droplets , 1999, Nature.