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The Impact of Ship-Produced Aerosols on the Microstructure and Albedo of Warm Marine Stratocumulus Clouds: A Test of MAST Hypotheses 1i and 1ii

Durkee, P. A. and Noone, K. J. and Ferek, R. J. and Johnson, D. W. and Taylor, J. P. and Garrett, T. J. and Hobbs, P. V. and Hudson, J. G. and Bretherson, C. S. and Innis, G. and Frick, G. M. and Hoppel, W. A. and O'Dowd, C. D. and Russell, L. M. and Gasparovic, R. and Nielsen, K. E. and Tessmer, S. A. and Öström, E. and Osborne, S. R. and Flagan, R. C. and Seinfeld, J. H. and Rand, H. (2000) The Impact of Ship-Produced Aerosols on the Microstructure and Albedo of Warm Marine Stratocumulus Clouds: A Test of MAST Hypotheses 1i and 1ii. Journal of the Atmospheric Sciences, 57 (16). pp. 2554-2569. ISSN 0022-4928. doi:10.1175/1520-0469(2000)057<2554:TIOSPA>2.0.CO;2.

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Anomalously high reflectivity tracks in stratus and stratocumulus sheets associated with ships (known as ship tracks) are commonly seen in visible and near-infrared satellite imagery. Until now there have been only a limited number of in situ measurements made in ship tracks. The Monterey Area Ship Track (MAST) experiment, which was conducted off the coast of California in June 1994, provided a substantial dataset on ship emissions and their effects on boundary layer clouds. Several platforms, including the University of Washington C-131A aircraft, the Meteorological Research Flight C-130 aircraft, the National Aeronautics and Space Administration ER-2 aircraft, the Naval Research Laboratory airship, the Research Vessel Glorita, and dedicated U.S. Navy ships, participated in MAST in order to study processes governing the formation and maintenance of ship tracks. This paper tests the hypotheses that the cloud microphysical changes that produce ship tracks are due to (a) particulate emission from the ship’s stack and/or (b) sea-salt particles from the ship’s wake. It was found that ships powered by diesel propulsion units that emitted high concentrations of aerosols in the accumulation mode produced ship tracks. Ships that produced few particles (such as nuclear ships), or ships that produced high concentrations of particles but at sizes too small to be activated as cloud drops in typical stratocumulus (such as gas turbine and some steam-powered ships), did not produce ship tracks. Statistics and case studies, combined with model simulations, show that provided a cloud layer is susceptible to an aerosol perturbation, and the atmospheric stability enables aerosol to be mixed throughout the boundary layer, the direct emissions of cloud condensation nuclei from the stack of a diesel-powered ship is the most likely, if not the only, cause of the formation of ship tracks. There was no evidence that salt particles from ship wakes cause ship tracks.

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URLURL TypeDescription<2554:TIOSPA>2.0.CO;2DOIArticle
Russell, L. M.0000-0002-6108-2375
Flagan, R. C.0000-0001-5690-770X
Seinfeld, J. H.0000-0003-1344-4068
Additional Information:© 2000 American Meteorological Society. Manuscript received 22 October 1997, in final form 12 February 1999. The MAST project and this paper specifically were supported by numerous grants to the various coauthors under the Office of Naval Research. Accelerated Research Initiative entitled Surface Ship Cloud Effects.
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Office of Naval Research (ONR)UNSPECIFIED
Issue or Number:16
Record Number:CaltechAUTHORS:20111128-081450625
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Official Citation:The Impact of Ship-Produced Aerosols on the Microstructure and Albedo of Warm Marine Stratocumulus Clouds: A Test of MAST Hypotheses 1i and 1ii P. A. Durkee, K. J. Noone, R. J. Ferek, D. W. Johnson, J. P. Taylor, T. J. Garrett, P. V. Hobbs, J. G. Hudson, C. S. Bretherton, G. Innis, G. M. Frick, W. A. Hoppel, C. D. O’Dowd, L. M. Russell, R. Gasparovic, K. E. Nielsen, S. A. Tessmer, E. Öström, S. R. Osborne, R. C. Flagan, J. H. Seinfeld, H. Rand
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:27958
Deposited By: Ruth Sustaita
Deposited On:28 Nov 2011 17:04
Last Modified:09 Nov 2021 16:53

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