Decadal oxygen change in the eastern tropical North Atlantic.

Hahn, Johannes, Brandt, Peter , Schmidtko, Sunke and Krahmann, Gerd (2017) Decadal oxygen change in the eastern tropical North Atlantic. Open Access Ocean Science, 13 (4). pp. 551-576. DOI 10.5194/os-13-551-2017.

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Supplementary data:

Abstract

Repeat shipboard and multi-year moored observations obtained in the oxygen minimum zone (OMZ) of the eastern tropical North Atlantic (ETNA) were used to study the decadal change in oxygen for the period 2006–2015. Along 23° W between 6 and 14° N, oxygen decreased with a rate of −5.9 ± 3.5 µmol kg−1 decade−1 within the depth covering the deep oxycline (200–400 m), while below the OMZ core (400–1000 m) oxygen increased by 4.0 ± 1.6 µmol kg−1 decade−1 on average. The inclusion of these decadal oxygen trends in the recently estimated oxygen budget for the ETNA OMZ suggests a weakened ventilation of the upper 400 m, whereas the ventilation strengthened homogeneously below 400 m. The changed ventilation resulted in a shoaling of the ETNA OMZ of −0.03 ± 0.02 kg m−3 decade−1 in density space, which was only partly compensated by a deepening of isopycnal surfaces, thus pointing to a shoaling of the OMZ in depth space as well (−22 ± 17 m decade−1). Based on the improved oxygen budget, possible causes for the changed ventilation are analyzed and discussed. Largely ruling out other ventilation processes, the zonal advective oxygen supply stands out as the most probable budget term responsible for the decadal oxygen changes.

Document Type: Article
Keywords: R.V. Thalassa; R.V. Ron Brown; R.V. L'Atalante
Research affiliation: OceanRep > SFB 754
OceanRep > SFB 754 > A4
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/os-13-551-2017
ISSN: 1812-0784
Related URLs:
Projects: SFB754, BMBF Nordatlantik, RACE, SOPRAN
Expeditions/Models/Experiments:
Date Deposited: 10 Jan 2017 08:17
Last Modified: 01 Feb 2019 15:01
URI: http://oceanrep.geomar.de/id/eprint/35550

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