Cruise MSM23 is supporting the Kiel Collaborative Research Centre SFB 754 ("Climate - Biogeochemistry Interactions in the Tropical Ocean"). The main goal within the framework of the SFB 754 is the quantification of oxygen supply to the oxygen minimum zone (OMZ).
The main objectives for MSM23 were:
1. High precision release of an artificial tracer as the beginning of the Oxygen Supply Tracer Release Experiment (OSTRE)
2. A survey of the oxygen minimum zone in the vicinity of the tracer release area
3. Recovery of gliders, that participated in a swarm experiment at the southern rim of the OMZ
Additional secondary objectives for MSM23 include:
1. Completion of a north-south section to observe the abundance of particles using the Underwater Vision Profiler (UVP)
2. Testing of a new oxygen sensor on the microstructure probe
3. Comparison of zooplankton abundance during the night and day using plankton net hauls
4. Underway measurements of upper ocean currents with the two shipboard ADCPs and hydrographic measurements with thermosalinograph, optode, pCO2 sensor and gas tension device (GTD) will be performed.
5. Full ocean depth CTD measurements to contribute to the global data set of deep ocean properties to evaluate slow long term changes.
The cruise was very successful and all objectives were reached and measurements were carried out as planned with only slight modifications.
Martin Visbeck (GEOMAR Helmholtz Centre for Ocean Research, Kiel (West Shore Campus))