Oxygen Supply Tracer Release Experiment (OSTRE) Tracer Injection - Cruise No. MSM23 - November 26 - December 20, 2012 - Mindelo (Cape Verde Islands) - Walvis Bay (Namibia) (English)

Cruise MSM23 is supporting the Kiel Collaborative Research Centre SFB 754 ("Climate - Biogeochemistry Interactions in the Tropical Ocean"). The cruise MSM23 was supporting one of the main goals within the framework of the SFB 754; the quantification of oxygen supply to the oxygen minimum zone (OMZ). Ventilation processes to be investigated include lateral and vertical mixing and oxygen advection (SP A3 and A4). The role of zooplankton for oxygen consumption and biogeochemical cycles (SP B8) was another minor focus of this cruise. During the cruise of MSM23 the Oxygen Supply Tracer Release Experiment (OSTRE) was started with the release of 88 kg of an artificial tracer roughly at 11° N 21° W and 430 m depth. Furthermore, the oxygen minimum zone has been examined in this region. At 5° N 23° W two gliders were recovered that had been released during the cruise MSM22 (Brandt). On two transects along 14.5° N and 21° W, the ocean was sampled with a station pattern of typically 30 nautical miles distance with CTD/Lowered ADCP/Underwater Vision Profiler (UVP) system. Some microstructure profiles and a day and night zooplankton net hauls completed the work program. In addition, underway measurements of upper ocean currents were performed with the two shipboard ADCPs and hydrographic measurements with thermosalinograph, optode, pCO2 sensor and gas tension device (GTD). A radio journalist accompanied the first days of the cruise. Also, two high school students from Kiel were on board, who carried out their own small research projects and were involved in the overall research program.