Mean state and variability of tropical Oxygen Minimum Zones in ocean models 

Seminar by Dr. Olaf Duteil from GEOMAR, Kiel, Germany

27 November 2023
KST 10:30 – 11:30

The Seminar is being held in Room 1010 (Jasmin) – Integrated mechanical engineering building. Click here for the campus map.

Oxygen levels are decreasing in the ocean at an alarming rate, leading to the expansion of Oxygen Minimum Zones (OMZs) particularly in the eastern part of the tropical Atlantic and Pacific Ocean. In the interior ocean, oxygen concentrations are determined by a complex balance between respiration of organisms and supply by ocean circulation. The mechanisms supplying oxygen will be detailed in a first part of the seminar and include tropical jets, both in the upper thermocline and at intermediate depth, isopycnal and mixing processes. The strength of the wind driven circulation and the tropical/subtropical cells (STCs) play a fundamental role in regulating tropical oxygen concentrations. In a second part of this seminar, the variability of the OMZs in ocean models will be discussed. Both the El Nino Southern Oscillation and low frequency climate variability modes, such as the Pacific Decadal Oscillation modulate ocean circulation, oxygen supply and OMZs. The focus of the third part of the seminar will be on the role of atmospheric synoptic features (storms, cyclones) which patterns and intensity may change in the future, impacting STCs, biogeochemical cycles, and oxygen levels. In conclusion, while our understanding of the mechanisms at play in regulating OMZs improved, representing the mean state, variability and future changes of oxygen levels in ocean models still remain a challenging task.