Ocean Deoxygenation Conference | Kiel 2018

Along the eastern boundaries of the eastern tropical Atlantic (ETA), intense oxygen minimum zones (OMZs) at intermediate depth result from the large remineralization of organic matter and the weak interior ventilation. The ETA is ventilated in the upper thermocline by the equatorial undercurrent (EUC). A part of the water transported by the EUC originate from the oxygen-rich subtropical regions, where subduction processes occur. The connection between subtropics and tropics is effectuated by wind driven shallow circulation cells, called subtropical-tropical cells (STC). To quantify the importance of the oxygen supply (in particular by the EUC and the STC) and the biological consumption, we perform simulations using an eddy resolving (1/10°) ocean model, embedded by a two-way nesting approach in a global coarse resolution model and coupled to a previously calibrated biogeochemical model that simulates phosphorus, oxygen, and nitrogen fluxes (MOPS-1.0). We perform two inter-decadal (1948 – 2007) experiments using two different atmospheric forcing data sets, CORE-II and JRA55-do. We show that the strength of the wind stress has a significant impact on the ocean circulation, the respiration rate and ultimately the oxygen levels.

Christina Roth, Olaf Duteil, Iris Kriest