CTD (Conductivity, Temperature, Depth)

German:  CTD-Kranzwasserschöpfer / CTD-Rosette

Gear construction: 24 Niskin bottles with 10 L volume each as well as sensors for measurements of the conductivity (for determination of the salinity), temperature, pressure (for determination of the depth), oxygen content, turbidity, and chlorophyll.

Dimensions: 1.55 x 1.55 x 1.9 m

Deployment: The CTD is connected to the computers on board by a cable and continuously measures all parameters. During lowering and raising of the CTD, the data is transmitted directly on board, so all measured values can be seen in a graph. On the top and on the bottom of each bottle lids are attached, which are open during the downcast to allow water flowing through. On the way back to the water surface, the lids can be closed in different depths from board to trap the water inside the bottles. As soon as the CTD comes back on deck, the water is taken from the bottles.

Maximum Depth: 6,000 m

Follow-up work: Transfer of the water into containers and further analysis in the lab by the different teams on board (e. g. filtration for eDNA).

Samples / Results: Depth profiles of the measured parameters & seawater samples from different depths.

CTD in the hangar of RV Sonne.
Deploying the CTD via the hover beam directly from the hangar.
Water penetration.
Last look at the CTD before it is lowered.