Conductivity, temperature and depth profiler (CTD)
So here we sit here at 1000 local time, an hour behind you in the UK. Its a gently rolling sea with blue sea, blue skies (have you looked at the webcam?) and a very pleasant morning. We have carried out the regular 2 CTD’s to 300m pre-dawn and today is one of the 2 deep CTD’s that we will sample in the Southern Atlantic gyre region down to the ocean floor, a few thousand metres below the sea surface.
“How deep do you want to go”, Terry asks. “Oh, 20 odd metres off the bottom will be fine, just as long as it’s safe. Don’t want to have to write a loss report to the Antarctic Survey, ho ho ho,” I say, slightly nervously. This is their brand new CTD system heading to the Antarctic for the very first time so quite important for a lot of forthcoming science! So about 90 minutes later it’s reached the bottom and we all came back to the readout screens to look at the salinity, temperature, oxygen etc. that will determine where we will fire the bottles for the water on the way back up.
The ships bottom read-out says 4380m and that also draws the ocean floor contours as we go along, quite interesting as it goes over sea-mounts and the like. “So what depth is the CTD”, I ask. “4430m”, says Terry. “What!! That’s technically 50 metres below the ocean floor”. A very nervous laugh from PSO, but Terry is happy that the depth is reading wrongly and the CTD is right, I just hope he/it is. But we really won’t know for another 90 minutes. Oh err, feels like a good time for something stronger than coffee, now where is that bottle of Plymouth…