METEOR M90

Longer periodic variability of dissolved oxygen (DO) has been observed in the oxygen minimum zones (OMZ) of the tropical oceans and will be investigated further on M90. The Meteor cruise M90 to the eastern tropical South Pacific Ocean is an effort of several groups of the DFG Collaborative Research Centre (SFB) 754 ‘Climate-biogeochemistry interactions in the tropical ocean’. The goal of the study is the quantification of the longer periodic variability in the oxygen minimum zone of the tropical South Pacific with the special focus on the role of the large scale circulation with the focus on the oxygen supply paths in tropical region as well as the southern boundary of the oxygen minimum zone.
Furthermore planned is a quantification of the oxygen distribution of an eddy for better estimates of lateral oxygen supply and ventilation of the oxygen minimum zone and an investigation of the variability of nutrient supply and utilisation (productivity) associated with eddies using stable Si and N isotope compositions of silicate and nitrate.
In addition, chemical parameters like nitrous oxide, short lived nitrogenous compounds and redox-sensitive species will be measured e.g. to identify microbial key processes of the nitrogen cycle in the OMZ off Peru.