HR: 0800h
AN: A41A-0021    [Abstracts]
TI: Characterizing Particle Morphology and Density by Combining Aerosol Measurements with Application to Modeling Ambient Aerosol Data from Pittsburgh Air Quality Study (2002) and ICARTT-2004
AU: * DeCarlo, P F
EM: decarlop@colorado.edu
AF: Cooperative Institute for Research in Enviromental Sciences (CIRES), University of Colorado UCB 216, Boulder, CO 80309-0216 United States
AU: * DeCarlo, P F
EM: decarlop@colorado.edu
AF: Program in Atmospheric and Oceanic Sciences (PAOS), University of Colorado UCB 311, Boulder, CO 80309-0311 United States
AU: Zhang, Q
EM: zhangq@cires.colorado.edu
AF: Cooperative Institute for Research in Enviromental Sciences (CIRES), University of Colorado UCB 216, Boulder, CO 80309-0216 United States
AU: Zhang, Q
EM: zhangq@cires.colorado.edu
AF: Department of Chemistry and Biochemistry, University of Colorado UCB 215, Boulder, CO 80309-0215 United States
AU: Worsnop, D
EM: worsnop@aerodyne.com
AF: Center for Aerosol and Cloud Chemistry, Aerodyne Research, Inc. 45 Manning Road, Billerica, MA 01821-3934 United States
AU: Slowik, J
EM: slowikja@bc.edu
AF: Department of Chemistry, Boston College 2609 Beacon Street, Chestnut Hill, MA 02467 United States
AU: Davidovits, P
EM: paul.davidovits@bc.edu
AF: Department of Chemistry, Boston College 2609 Beacon Street, Chestnut Hill, MA 02467 United States
AU: Cubison, M
EM: m.cubison@postgrad.umist.ac.uk
AF: Department of Physics, UMIST PO Box 88, Manchester, M60 1QD United Kingdom
AU: Allan, J
EM: james.allan@physics.org
AF: Department of Physics, UMIST PO Box 88, Manchester, M60 1QD United Kingdom
AU: Cross, E
EM: espencer@aerodyne.com
AF: Center for Aerosol and Cloud Chemistry, Aerodyne Research, Inc. 45 Manning Road, Billerica, MA 01821-3934 United States
AU: Cross, E
EM: espencer@aerodyne.com
AF: Department of Chemistry, Boston College 2609 Beacon Street, Chestnut Hill, MA 02467 United States
AU: Jimenez, J
EM: jose.jimenez@colorado.edu
AF: Cooperative Institute for Research in Enviromental Sciences (CIRES), University of Colorado UCB 216, Boulder, CO 80309-0216 United States
AU: Jimenez, J
EM: jose.jimenez@colorado.edu
AF: Department of Chemistry and Biochemistry, University of Colorado UCB 215, Boulder, CO 80309-0215 United States
AB: Different on-line particle sizing techniques report different "equivalent diameters." For example differential mobility analyzers (DMAs) report particle mobility diameter (d$_{m}$), while a number of recently developed instruments (such as the Aerodyne Aerosol Mass Spectrometer, or AMS) can measure vacuum aerodynamic diameter (d$_{va}$). Particle density and morphology have important effects on diameter measurements, leading to differences in the measurements of different instruments that can be exploited to extract information on these particle properties. This Poster presents a framework for combining the information content of different diameter measurements into a single coherent mathematical description of the particles. We show that combining d$_{m}$ and d$_{va}$ measurements for the same particle population allows the placing of constraints on particle density, dynamic shape factor ($\chi$), and fraction of internal void space. Additional information from other measurements, and/or adding some assumptions allows the determination of all parameters. In particular, particle volume and mass can be determined from d$_{m}$ and d$_{va}$ measurements if the particle density is known, and with the assumption $\chi$ does not depend on the flow regime. The amount of information that can be deduced from the combination of d$_{m}$ and d$_{va}$ measurements for various model particle types is shown. A computer model to integrate ambient aerosol measurements from a scanning mobility particle sizer (SMPS) and an AMS is also developed based on the framework developed. Test cases from the Pittsburgh EPA Supersite (2002) are presented. The model fits the ambient data with 3 internally mixed lognormal modes of independent composition utilizing a Levenberg-Marquardt algorithm. This analysis provides information on shape and density of each of the three fitted modes of the ambient aerosol. The model will also be applied to recent results from Chebogue Point, Nova Scotia (ICARTT-2004) with the resulting model output used as an input to a CCN formation model. The modeled aerosol CCN activation will be compared to the measured CCN activation data from the same time period.
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0320 Cloud physics and chemistry
DE: 0345 Pollution--urban and regional (0305)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting