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| Titel |
Diapycnal oxygen supply to the tropical North Atlantic oxygen minimum zone |
| VerfasserIn |
Tim Fischer, Donata Banyte, Peter Brandt, Marcus Dengler, Gerd Krahmann, Toste Tanhua, Martin Visbeck |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082021
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| Zusammenfassung |
| The replenishment of consumed oxygen in the open ocean oxygen minimum zone (OMZ)
off West Africa in the tropical North Atlantic Ocean is studied, with a focus on
oxygen transport across density surfaces (diapycnal flux). The latter is obtained
from a large observational set of oxygen profiles and diapycnal mixing data from
years 2008 to 2010. Diapycnal mixing is inferred from different sources: a large
scale tracer release experiment, microstructure profiles, and shipboard acoustic
current measurements plus density profiles. The average diapycnal diffusivity in the
study area is 1 -
10-5 m2 s-1. No significant vertical gradient of average diapycnal
diffusivities exists in the depth interval from 150 to 500 m. The diapycnal flux is found to
contribute substantially to the oxygen supply of the OMZ. Within the OMZ core, 1.5
μmolkg-1 a-1 of oxygen is supplied via diapycnal mixing, contributing about a third of the
total demand. The oxygen that is contributed via diapycnal mixing originates from
oxygen that has been laterally supplied within the overlying Central Water layer
by advective and eddy fluxes. Due to the existence of a separate shallow oxygen
minimum at about 100 m depth throughout most of the study area, there is no direct net
vertical oxygen flux from the surface layer of the study area into the Central Water
layer. Thus all oxygen supply of the OMZ is associated with remote pathways. |
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