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Impact of ship emissions on the microphysical, optical and radiative properties of marine stratus: a case study

Schreier, M. and Kokhanovsky, A.A. and Eyring, V. and Bugliaro, L. and Mannstein, H. and Mayer, B. and Bovensmann, H. and Burrows, J.P. (2006) Impact of ship emissions on the microphysical, optical and radiative properties of marine stratus: a case study. Atmospheric Chemistry and Physics, 6, pp. 4925-4942.

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Official URL: http://www.atmos-chem-phys.net/6/4925/2006/

Abstract

Modifications of existing clouds by the exhaust of ships are well-known but inadequately quantified impacts, which could contribute to climate change. The perturbation of a cloud layer by ship-generated aerosol changes the cloud reflectivity and is identified by long curves in satellite images, known as ship tracks. As ship tracks indicate a pollution of a very clean marine environment and also affect the radiation budget below and above the cloud, it is important to investigate their radiative and climatic effects. Satellitedata from MODIS on Terra are used to examine a scene from 10 February 2003 where ship tracks were detected close to the North American West-Coast. The cloud optical and microphysical properties are derived using a semi-analytical retrieval technique combined with a look-up-table approach. An algorithm is presented to distinguish ship-track-pixels from the unperturbed cloud pixels in the scene and from this the optical properties of the former are compared to those of the latter. Within the ship tracks a significant change in the droplet number concentration, the effective radius and the optical thickness are found compared to the unaffected cloud. The resulting cloud properties are used to calculate the radiation budget below and above the cloud. Assuming a mean solar zenith angle of 63° for the selected scene, the mean solar surface radiation below the ship track is decreased by 43.2Wm<sup>-2</sup> and the mean reflectance at top of atmosphere (TOA) is increased by 40.8Wm<sup>-2</sup>. For the entire analyzed scene the ship emission decreases the solar radiation at the surface by 2.1Wm<sup>-2</sup> and increases the backscattered solar radiation at TOA by 2.0Wm<sup>-2</sup> , whereas no significant effect on thermal radiation was detected.

Document Type:Article
Title:Impact of ship emissions on the microphysical, optical and radiative properties of marine stratus: a case study
Authors:
AuthorsInstitution or Email of Authors
Schreier, M.Univ. of Bremen, Bremen
Kokhanovsky, A.A.Univ. of Bremen, Bremen
Eyring, V.UNSPECIFIED
Bugliaro, L.UNSPECIFIED
Mannstein, H.UNSPECIFIED
Mayer, B.UNSPECIFIED
Bovensmann, H.Univ. of Bremen, Bremen
Burrows, J.P.Univ. of Bremen, Bremen
Date:2006
Journal or Publication Title:Atmospheric Chemistry and Physics
Refereed publication:Yes
In Open Access:Yes
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:6
Page Range:pp. 4925-4942
Status:Published
Keywords:climate change, ship emissions, marine stratus
HGF - Research field:Aeronautics, Space and Transport (old)
HGF - Program:Space (old)
HGF - Program Themes:W EO - Erdbeobachtung
DLR - Research area:Space
DLR - Program:W EO - Erdbeobachtung
DLR - Research theme (Project):W - Vorhaben Atmosphären- und Klimaforschung (old)
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Atmospheric Physics > Atmospheric Remote Sensing
Institute of Atmospheric Physics > Atmospheric Dynamics
Deposited By: Jana Freund
Deposited On:13 Sep 2007
Last Modified:11 Nov 2014 21:56

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