Impact of the marine atmospheric boundary layer conditions on VSLS abundances in the eastern tropical and subtropical North Atlantic Ocean.

Fuhlbruegge, Steffen, Krüger, Kirstin, Quack, Birgit, Atlas, E., Hepach, Helmke and Ziska, Franziska (2013) Impact of the marine atmospheric boundary layer conditions on VSLS abundances in the eastern tropical and subtropical North Atlantic Ocean. Open Access Atmospheric Chemistry and Physics, 13 (13). pp. 6345-6357. DOI 10.5194/acp-13-6345-2013.

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During the DRIVE (Diurnal and Regional Variability of Halogen Emissions) ship campaign we investigated the variability of the halogenated very short-lived substances (VSLS) bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I) in the marine atmospheric boundary layer in the eastern tropical and subtropical North Atlantic Ocean during May/June 2010. The highest VSLS mixing ratios were found near the Mauritanian coast and close to Lisbon (Portugal). With backward trajectories we identified predominantly air masses from the open North Atlantic with some coastal influence in the Mauritanian upwelling area, due to the prevailing NW winds. The maximum VSLS mixing ratios above the Mauritanian upwelling were 8.92 ppt for bromoform, 3.14 ppt for dibromomethane and 3.29 ppt for methyl iodide, with an observed maximum range of the daily mean up to 50% for bromoform, 26% for dibromomethane and 56% for methyl iodide. The influence of various meteorological parameters - such as wind, surface air pressure, surface air and surface water temperature, humidity and marine atmospheric boundary layer (MABL) height - on VSLS concentrations and fluxes was investigated. The strongest relationship was found between the MABL height and bromoform, dibromomethane and methyl iodide abundances. Lowest MABL heights above the Mauritanian upwelling area coincide with highest VSLS mixing ratios and vice versa above the open ocean. Significant high anti-correlations confirm this relationship for the whole cruise. We conclude that especially above oceanic upwelling systems, in addition to sea-air fluxes, MABL height variations can influence atmospheric VSLS mixing ratios, occasionally leading to elevated atmospheric abundances. This may add to the postulated missing VSLS sources in the Mauritanian upwelling region (Quack et al., 2007).

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/FP7/226224
Additional Information: WOS:000321767200014
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Refereed: Yes
Open Access Journal?: Yes
Publisher: Copernicus Publications (EGU)
Projects: SOPRAN, SHIVA, DRIVE, Future Ocean
Date Deposited: 28 Aug 2013 08:59
Last Modified: 24 Sep 2019 00:06

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