HR: 14:10h
AN: A33G-03 INVITED [Abstracts]
TI: Secondary Organic Aerosol Formation in Clouds: A Synthesis of Data From Four Field Campaigns
AU: * Sorooshian, A
EM: armin@caltech.edu
AF: Departments of Chemical Engineering and Environmental Science and Engineering,
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Brechtel, F J
EM: fredbmi@sbcglobal.net
AF: Departments of Chemical Engineering and Environmental Science and Engineering,
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Brechtel, F J
EM: fredbmi@sbcglobal.net
AF: Brechtel Manufacturing Inc., 1789 Addison Way, Hayward, CA 94544, United States
AU: Lu, M
EM: julialu@caltech.edu
AF: Departments of Chemical Engineering and Environmental Science and Engineering,
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Feingold, G
EM: Graham.Feingold@noaa.gov
AF: Earth System Research Laboratory/Chemical Sciences Division, National Oceanic and
Atmospheric Administration, 325 Broadway, Boulder, CA 80305, United States
AU: Ervens, B
EM: Barbara.Ervens@noaa.gov
AF: Earth System Research Laboratory/Chemical Sciences Division, National Oceanic and
Atmospheric Administration, 325 Broadway, Boulder, CA 80305, United States
AU: Ervens, B
EM: Barbara.Ervens@noaa.gov
AF: Atmospheric Science Department, Colorado State University, 200 West Lake Street, Fort
Collins, CA 80523, United States
AU: Jonsson, H
EM: hjonsson@nps.navy.mil
AF: Center for Interdisciplinary Remotely Piloted Aircraft Studies, Naval Postgraduate School,
3200 Imjin Rd., Hangar 507, Marina, CA 93933, United States
AU: Flagan, R C
EM: flagan@caltech.edu
AF: Departments of Chemical Engineering and Environmental Science and Engineering,
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AU: Seinfeld, J H
EM: seinfeld@caltech.edu
AF: Departments of Chemical Engineering and Environmental Science and Engineering,
California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, United States
AB:
There is growing evidence, based on laboratory and ambient measurements, that secondary organic aerosol
(SOA) is formed by aqueous-phase reactions in cloud droplets. Owing to the low volatility and water-soluble
nature of organic acids, these species constitute a significant fraction of SOA mass. Airborne particle-into-liquid
sampler (PILS-coupled to ion chromatography) measurements made on the Center for Interdisciplinary
Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter are presented from four separate field campaigns
representing urban and marine atmospheres: International Consortium for Atmospheric Research on Transport
and Transformation (ICARTT 2004), Marine Stratus/Stratocumulus Experiment I and II (MASE 2005, 2007), Gulf of
Mexico Atmospheric Composition and Climate Study (GoMACCS 2006). Sulfate and oxalate are strongly
correlated in ambient aerosols, especially evaporated cloud droplet residual particles. Since their chemical
formation mechanisms are not directly linked, this correlation can be explained by a common medium necessary
for production: droplets. Enhanced organic acid aerosol layers have been observed directly above cloudtops in
both marine and urban atmospheres; as derived from large eddy simulations of stratocumulus under the
conditions of MASE, both Lagrangian trajectory analysis and diurnal cloudtop evolution provide evidence that a
significant fraction of the aerosol mass concentration above cloud can be accounted for by evaporated droplet
residual particles. Predictions from a chemical cloud parcel model considering the aqueous-phase production of
organic acids and sulfate show good agreement with ambient data for the relative magnitude of sulfate and
organic acid growth in clouds and also the evolution of oxalic acid and its aqueous-phase precursors with
increasing altitude in cloud.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0320 Cloud physics and chemistry
DE: 0322 Constituent sources and sinks
DE: 3311 Clouds and aerosols
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting