Joint Seminar: Representation of oxygen minimum zones in circulation biogeochemical models

In order to understand the causes of the observed expansion of tropical ocean's oxygen minimum zones (OMZs), one need to disentangle the role of biogeochemical and circulation processes. In particular, the equatorial current system plays a major role in ventilating the eastern side of the Atlantic and Pacific basin. The role of this current system is evaluated comparing a coarse (0.5°) to an eddy resolving (0.1°) configuration (NEMO3.1 model). The improvement of OMZs in the eddy resolving configuration is traced to a stronger oxygen supply by a more realistic representation of the equatorial and off-equatorial undercurrents, outweighing the concurrent increase in oxygen consumption associated with the stronger nutrient supply. At a larger scale, the strength of the equatorial current system is associated with the Subtropical-Tropical Cells (STCs), which intensity depends of the wind forcing. We evaluate the impact of the STC variability on the oxygen content in the whole tropical Pacific ocean using a coarse (0.5°) configuration. Our results suggest that the observed recent strengthening of the STCs will lead to a pause in the oxygen decrease or even an increase of oxygen values in the near future. 




13:30 Uhr


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Olaf Duteil, GEOMAR


Tatiana Ilyina

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