Sea-to-air and diapycnalnitrous oxide fluxes in the eastern tropical North Atlantic Ocean

Kock, Annette, Schafstall, Jens, Dengler, Marcus, Brandt, Peter and Bange, Hermann W. (2012) Sea-to-air and diapycnalnitrous oxide fluxes in the eastern tropical North Atlantic Ocean Biogeosciences (BG), 9 . pp. 957-964. DOI 10.5194/bg-9-957-2012.

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Abstract

Sea-to-air and diapycnal fluxes of nitrous oxide
(N2O) into the mixed layer were determined during three cruises to the upwelling region off Mauritania. Sea-to-air fluxes as well as diapycnal fluxes were elevated close to the
shelf break, but elevated sea-to-air fluxes reached further offshore as a result of the offshore transport of upwelled water masses. To calculate a mixed layer budget for N2O we compared the regionally averaged sea-to-air and diapycnal fluxes and estimated the potential contribution of other processes, such as vertical advection and biological N2O production in the mixed layer. Using common parameterizations for the gas transfer velocity, the comparison of the average sea-toair and diapycnal N2O fluxes indicated that the mean sea-toair flux is about three to four times larger than the diapycnal flux. Neither vertical and horizontal advection nor biological production were found sufficient to close the mixed layer budget. Instead, the sea-to-air flux, calculated using a parameterization that takes into account the attenuating effect of surfactants on gas exchange, is in the same range as the diapycnal flux. From our observations we conclude that
common parameterizations for the gas transfer velocity likely overestimate the air-sea gas exchange within highly productive upwelling zones.

Document Type: Article
Additional Information: WOS:000302179500006
Keywords: Physical Oceanography; Marine chemistry; Biogeochemistry; N2O, upwelling, air-sea exchange, diopycnal fluxes; AS-EXCHANGE; SURFACE MICROLAYERS; ARABIAN SEA; NITRIFICATION; DISSIPATION; ZONE; EMISSIONS; BACTERIA; OXYGEN; RATES; POS347; POS348; ATA_IFMGEOMAR/3; M80/2; POSEIDON; L'Atlante; METEOR
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
OceanRep > The Future Ocean - Cluster of Excellence
Refereed: Yes
DOI etc.: 10.5194/bg-9-957-2012
ISSN: 1726-4170
Projects: SOPRAN, Future Ocean
Expeditions/Models:
Date Deposited: 08 Mar 2012 13:35
Last Modified: 17 Sep 2015 13:25
URI: http://eprints.uni-kiel.de/id/eprint/13966

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