MARIA S. MERIAN MSM23

MERIAN cruise MSM 23 in the tropical At-lantic Ocean is a contribution to the DFG Sonderforschungsbereich (SFB) 754, Cli-mate - Biogeochemistry Interactions in the Tropical Ocean, subproject A3. The goal of the study is to quantify and better understand the supply of oxygen to the oxygen minimum zone (OMZ) of the Tropical Atlantic with a particular focus on the role of submesoscale processes for lateral and vertical oxygen fluxes and thus a critical aspect of the ventilation of this region. The “Oxygen Supply Tracer Release Experiment (OSTRE) will be launched in order to quantify diapycnal and lateral mixing rates in the region. This cruise is closely related to cruise MSM 22 (Brandt). This cruise will recover a small fleet of gliders that were deployed by the previous cruise, thus optimizing the life time (about one month) of the gliders operational endurance.
The main goals of the work are:
• Quantification of the strength of mesoscale and submesoscale transports and their in-fluence on the oxygen distribution via esti-mates of lateral mixing and ventilation of the OMZ by means of a tracer release exper-iment.
• Determination of isopycnal and diapycnal mixing coefficients.
The work of this cruise will focus on the deployment of the tracer SF5CF3 near the OMZ at around 11°N and about 500 meters depth (potential density ~27.2 kg/m3), i.e. the initial step in the tracer release experiment.
Additional work will include bio-geochemical sampling in the layer marked by the tracer and on the CTD transects.





The research vessel MARIA S. MERIAN meets the Cape Verdean research vessel ISLANDIA at the Cape Verde Ocean Observatory. Photo: Rike Pöhl




The Ocean Tracer Injection System OTIS is launched. Photo: M. Visbeck, GEOMAR




CTD launch. Photo: M. Visbeck, GEOMAR




Microstructure probe. Photo: M. Visbeck, GEOMAR