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| Williams, J.; Custer, T.; Riede, H.; Sander, R.; Joeckel, P.; Hoor, P.; Pozzer, A.; Wong-zehnpfennig, S.; Beygi, Z. Hosaynali; Fischer, H.; Gros, V.; Colomb, A.; Bonsang, B.; Yassaa, N.; Peeken, I.; Atlas, E. L.; Waluda, C. M.; Van Aardenne, J. A.; Lelieveld, J.. |
| Ship-borne measurements have been made in air over the remote South Atlantic and Southern Oceans in January-March 2007. This cruise encountered a large-scale natural phytoplankton bloom emitting reactive hydrocarbons (e. g. isoprene); and a high seas squid fishing fleet emitting NOx (NO and NO2). Using an atmospheric chemistry box model constrained by in-situ measurements, it is shown that enhanced ozone production ensues from such juxtaposed marine biogenic and anthropogenic emissions. The relative impact of shipping and phytoplankton emissions on ozone was examined on a global scale using the EMAC model. Ozone in the marine boundary layer was found to be over ten times more sensitive to NOx emissions from ships, than to marine isoprene in the region... |
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| Ano: 2010 |
URL: https://archimer.ifremer.fr/doc/00231/34260/32628.pdf |
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| Violaki, K.; Sciare, J.; Williams, J.; Baker, A. R.; Martino, M.; Mihalopoulos, N.. |
| To obtain a comprehensive picture of the spatial distribution of water-soluble organic nitrogen (WSON) in marine aerosols, samples were collected during research cruises in the tropical and southern Atlantic Ocean and also in the southern Indian Ocean (Amsterdam Island) for a 1-year period (2005). Samples were analyzed for both organic and inorganic forms of nitrogen, and the factors controlling their levels were examined. Fine-mode WSON was found to play a significant role in the remote marine atmosphere with enhanced biogenic activity, with concentrations of WSON (11.3 +/- 3.3 nmol N m(-3)) accounting for about 84% of the total dissolved nitrogen (TDN). Such concentrations are similar to those observed in the polluted marine atmosphere of the eastern... |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00291/40253/38630.pdf |
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| Arnold, S. R.; Spracklen, D. V.; Williams, J.; Yassaa, N.; Sciare, J.; Bonsang, B.; Gros, V.; Peeken, I.; Lewis, A. C.; Alvain, S.; Moulin, C.. |
| We have combined the first satellite maps of the global distribution of phytoplankton functional type and new measurements of phytoplankton-specific isoprene productivities, with available remote marine isoprene observations and a global model, to evaluate our understanding of the marine isoprene source and its impacts on organic aerosol abundances. Using satellite products to scale up data on phytoplankton-specific isoprene productivity to the global oceans, we infer a mean "bottom-up" oceanic isoprene emission of 0.31 +/- 0.08 (1 sigma) Tg/yr. By minimising the mean bias between the model and isoprene observations in the marine atmosphere remote from the continents, we produce a "top-down" oceanic isoprene source estimate of 1.9 Tg/yr. We suggest our... |
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| Ano: 2009 |
URL: https://archimer.ifremer.fr/doc/00218/32915/31411.pdf |
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| Beygi, Z. Hosaynali; Fischer, H.; Harder, H. D.; Martinez, M.; Sander, R.; Williams, J.; Brookes, D. M.; Monks, P. S.; Lelieveld, J.. |
| Ozone (O-3) is a photochemical oxidant, an air pollutant and a greenhouse gas. As the main precursor of the hydroxyl radical (OH) it strongly affects the oxidation power of the atmosphere. The remote marine boundary layer (MBL) is considered an important region in terms of chemical O-3 loss; however surface-based atmospheric observations are sparse and the photochemical processes are not well understood. To investigate the photochemistry under the clean background conditions of the Southern Atlantic Ocean, ship measurements of NO, NO2, O-3, J(NO2), J((OD)-D-1), HO2, OH, ROx and a range of meteorological parameters were carried out. The concentrations of NO and NO2 measured on board the French research vessel Marion-Dufresne (28 degrees S-57 degrees S, 46... |
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| Ano: 2011 |
URL: https://archimer.ifremer.fr/doc/00092/20310/17959.pdf |
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