The rosette

Tara is an expedition, monitored by the EU scientific program Damocles, and is providing a dynamic platform for observations of global warming. The CTD (conductivity, temperature, depth) is one of the key instrument onboard Tara. It takes samples of water at different depths of one area just below the boat, at one given time. Details such as the water temperature and its salinity are variable depending on the depth of the ocean it was taken from.

 

What information has this data bring in the last month and a half of collecting?

In this area, the CTD saves with great details the depth of the various layers in the ocean.

At the moment, the surface layer goes from 0 to -40 metre deep, with a temperature of -1,8 °C. It is relatively mildly saline water.  

Between – 200 et – 400 meter deep, a second very typical layer called the “Atlantic” layer, which is much more saline with positive temperatures around + 1,5 °C.

Lastly, between 400 meter and the bottom of the seas, is found a deep water layer with a salinity level equal to the one above and negative temperature of - 0,6 °C. This composition is typical of the Arctic Ocean. Sharp variation of this data defines the limits, these different regions differing in temperatureare called by the scientists thermocline, and halocline are the (sometimes indistinct) border between layers of water that contain different amounts of salt.

The CTD greatness lies in its ability to verify the structure composition which varies according to miscellaneous parameters such as the sampling area and the evolution of the climatic conditions.

Thanks to the CTD can be verified that the Atlantic layer is thickening as you are getting nearer to the Ocean of the same name.