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Ship impacts on the marine atmosphere: insights into the contribution of shipping emissions to the properties of marine aerosol and clouds

Coggon, M. M. and Sorooshian, A. and Wang, Z. and Metcalf, A. R. and Frossard, A. A. and Lin, J. J. and Craven, J. S. and Nenes, A. and Jonsson, H. H. and Russell, L. M. and Flagan, R. C. and Seinfeld, J. H. (2012) Ship impacts on the marine atmosphere: insights into the contribution of shipping emissions to the properties of marine aerosol and clouds. Atmospheric Chemistry and Physics, 12 (18). pp. 8439-8458. ISSN 1680-7316. doi:10.5194/acp-12-8439-2012.

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We report properties of marine aerosol and clouds measured in the shipping lanes between Monterey Bay and San Francisco off the coast of Central California. Using a suite of aerosol instrumentation onboard the CIRPAS Twin Otter aircraft, these measurements represent a unique set of data contrasting the properties of clean and ship-impacted marine air masses in dry aerosol and cloud droplet residuals. Below-cloud aerosol exhibited average mass and number concentrations of 2 μg m^(−3) and 510 cm^(−3), respectively, which are consistent with previous studies performed off the coast of California. Enhancements in vanadium and cloud droplet number concentrations are observed concurrently with a decrease in cloud water pH, suggesting that periods of high aerosol loading are primarily linked to increased ship influence. Mass spectra from a compact time-of-flight Aerodyne aerosol mass spectrometer reveal an enhancement in the fraction of organic at m/z 42 (f_42) and 99 (f_99) in ship-impacted clouds. These ions are well correlated to each other (R^2>0.64) both in and out of cloud and constitute 14% (f_(44)) and 3% (f_(99)) of organic mass during periods of enhanced sulfate. High-resolution mass spectral analysis of these masses from ship measurements suggests that the ions responsible for this variation were oxidized, possibly due to cloud processing. We propose that the organic fractions of these ions be used as a metric for determining the extent to which cloud-processed ship emissions impact the marine atmosphere where (f_(42) > 0.15; f_(99) > 0.04) would imply heavy influence from shipping emissions, (0.05 < f_(42) < 0.15; 0.01 < f_(99) < 0.04) would imply moderate, but persistent, influences from ships, and (f_(42) < 0.05; f_(99) < 0.01) would imply clean, non-ship-influenced air.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Coggon, M. M.0000-0002-5763-1925
Sorooshian, A.0000-0002-2243-2264
Wang, Z.0000-0002-7921-3134
Metcalf, A. R.0000-0003-0385-1356
Frossard, A. A.0000-0002-5728-0854
Nenes, A.0000-0003-3873-9970
Jonsson, H. H.0000-0003-3043-1074
Russell, L. M.0000-0002-6108-2375
Flagan, R. C.0000-0001-5690-770X
Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© 2012 Author(s). This work is distributed under the Creative Commons Attribution 3.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 22 May 2012. Published in Atmos. Chem. Phys. Discuss.: 7 June 2012. Revised: 1 September 2012. Accepted: 3 September 2012. Published: 20 September 2012. Edited by: R. Krejci. This work was funded by ONR grants N00014-11-1-0783, N00014-10-1-0200, and N00014-10-1-0811, and NSF grants AGS-1013381 and AGS-1008848. We acknowledge Dean Hegg for providing the cloud water collector.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-11-1-0783
Office of Naval Research (ONR)N00014-10-1-0200
Office of Naval Research (ONR)N00014-10-1-0811
Issue or Number:18
Record Number:CaltechAUTHORS:20121113-133911100
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Official Citation:Coggon, M. M., Sorooshian, A., Wang, Z., Metcalf, A. R., Frossard, A. A., Lin, J. J., Craven, J. S., Nenes, A., Jonsson, H. H., Russell, L. M., Flagan, R. C., and Seinfeld, J. H.: Ship impacts on the marine atmosphere: insights into the contribution of shipping emissions to the properties of marine aerosol and clouds, Atmos. Chem. Phys., 12, 8439-8458, doi:10.5194/acp-12-8439-2012, 2012.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:35440
Deposited By: Ruth Sustaita
Deposited On:13 Nov 2012 22:02
Last Modified:09 Nov 2021 23:15

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