CTD equipment
CTD equipment
What you need to collect data from the sea
When you go out to sea on a research vessel, the aim of the voyage is to collect information in the form of data. There are many devices on board the ship that can collect this data for the researchers. One of these devices is the CTD probe.
CTD probeThe letters CTD stand for Conductivity, Temperatureand Depth. In German, this means conductivity, temperature and depth. The eponymous values are always measured. Additional probes are installed for all other parameters of interest. These include a sensor for the oxygen content. Some conclusions can be drawn from the measured values. For example, the circulation of the oceans can be traced. The picture shows a so-called crane water sampler, which is usually combined with a CTD probe (therefore often called a CTD rosette). It can be used to take water samples. As can be clearly seen in the picture, several bottles are attached to the device. These are open at the top and bottom. When the water sampler is lowered into the sea, the water flows through the bottles. As soon as the probe has reached the desired depth, the first bottles are closed. This is easily done at the click of a mouse from the ship. When the CTD is pulled up, further samples are taken at the predetermined depths. |
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Deck unitThe deck unit is the device that processes the data transmitted by the CTD probe during the dive. Without this unit, it would not be possible to record any data. The data is read into the PC via the deck unit. Conversely, the commands that are executed on the PC are forwarded to the probe via the deck unit. |  |
Fun fact:
The cover unit is an old technology that is actually no longer needed, as computers today are able to execute the necessary commands. However, there is no modern replacement that could forward the commands to the probe.
Altimeter: a safety device
An altimeter is an altimeter². In this case, it is attached to the probe and measures the distance to the seabed. It indicates the pressure difference. The deeper the probe, the higher the pressure. In addition, a 2 metre long rope is attached to the bottom of the probe from which a weight is suspended. If it hits the bottom, a signal is triggered and the cable winch is stopped.
And very important: a PC
For further reading:
1. (29 May 2021). Retrieved from www.geomar.de/forschen/fb1/fb1-po/beobachtungssysteme/ctd
2. (29 May 2021). Retrieved from de.wikipedia.org/wiki/H%C3%B6henmesser