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Advances in Meteorology
Volume 2010 (2010), Article ID 830846, 7 pages
http://dx.doi.org/10.1155/2010/830846
Research Article

Wind Speed Influences on Marine Aerosol Optical Depth

1School of Physics & Centre for Climate and Air Pollution Studies, Environmental Change Institute, National University of Ireland Galway, University Road, Galway, Ireland
2Université Paris 6, LATMOS/IPSL, CNRS/INSU, 75005 Paris, France
3Global Model Evaluation and Development, Met Office, Exeter, Devon EX1 3PB, UK

Received 18 February 2010; Revised 18 July 2010; Accepted 21 August 2010

Academic Editor: David Kieber

Copyright © 2010 Colin O'Dowd et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The Mulcahy (Mulcahy et al., 2008) power-law parameterization, derived at the coastal Atlantic station Mace Head, between clean marine aerosol optical depth (AOD) and wind speed is compared to open ocean MODIS-derived AOD versus wind speed. The reported AOD versus wind speed (U) was a function of ~ U2. The open ocean MODIS-derived AOD at 550 nm and 860 nm wavelengths, while in good agreement with the general magnitude of the Mulcahy parameterization, follows a power-law with the exponent ranging from 0.72 to 2.47 for a wind speed range of 2–18 m s 1 . For the four cases examined, some MODIS cases underestimated AOD while other cases overestimated AOD relative to the Mulcahy scheme. Overall, the results from MODIS support the general power-law relationship of Mulcahy, although some linear cases were also encountered in the MODIS dataset. Deviations also arise between MODIS and Mulcahy at higher wind speeds (>15 m s 1 ), where MODIS-derived AOD returns lower values as compared to Mulcahy. The results also support the suggestion than wind generated sea spray, under moderately high winds, can rival anthropogenic pollution plumes advecting out into marine environments with wind driven AOD contributing to AOD values approaching 0.3.