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On the Source of Organic Acid Aerosol Layers above Clouds

Sorooshian, Armin and Lu, Miao-Ling and Brechtel, Fred J. and Jonsson, Haflidi and Feingold, Graham and Flagan, Richard C. and Seinfeld, John H. (2007) On the Source of Organic Acid Aerosol Layers above Clouds. Environmental Science and Technology, 41 (13). pp. 4647-4654. ISSN 0013-936X. doi:10.1021/es0630442.

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During the July 2005 Marine Stratus/Stratocumulus Experiment (MASE) and the August−September 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosols and cumulus clouds in the eastern Pacific Ocean off the coast of northern California and in southeastern Texas, respectively. An on-board particle-into-liquid sampler (PILS) quantified inorganic and organic acid species with ≤5-min time resolution. Ubiquitous organic aerosol layers above cloud with enhanced organic acid levels were observed in both locations. The data suggest that aqueous-phase reactions to produce organic acids, mainly oxalic acid, followed by droplet evaporation is a source of elevated organic acid aerosol levels above cloud. Oxalic acid is observed to be produced more efficiently relative to sulfate as the cloud liquid water content increases, corresponding to larger and less acidic droplets. 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. Methanesulfonate data suggest that entrainment of free tropospheric aerosol can also be a source of organic acids above boundary layer clouds.

Item Type:Article
Related URLs:
URLURL TypeDescription
Sorooshian, Armin0000-0002-2243-2264
Jonsson, Haflidi0000-0003-3043-1074
Flagan, Richard C.0000-0001-5690-770X
Seinfeld, John H.0000-0003-1344-4068
Additional Information:© 2007 American Chemical Society. Received for review December 21, 2006. Revised manuscript received April 6, 2007. Accepted April 20, 2007. This work was supported by NOAA grant NA06OAR4310082 and Office of Naval Research grant N00014-04-1-0118. The authors gratefully acknowledge the NOAA Air Resources Laboratory (ARL) for provision of the HYSPLIT transport and dispersion model.
Funding AgencyGrant Number
National Oceanic and Atmospheric Administration (NOAA)NA06OAR4310082
Office of Naval Research (ONR)N00014-04-1-0118
Issue or Number:13
Record Number:CaltechAUTHORS:20150818-111158831
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Official Citation:On the Source of Organic Acid Aerosol Layers above Clouds Armin Sorooshian, Miao-Ling Lu, Fred J. Brechtel, Haflidi Jonsson, Graham Feingold, Richard C. Flagan, and John H. Seinfeld Environmental Science & Technology 2007 41 (13), 4647-4654 DOI: 10.1021/es0630442
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59730
Deposited By: Irina Meininger
Deposited On:19 Aug 2015 20:30
Last Modified:10 Nov 2021 22:24

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