The CTD is the workhorse of most of the oceanographic research that happens on the Oden or any other research vessel.  CTD stands for Conductivity, Temperature and Depth and the heart of this “inner space probe” is a package of instruments that sends a stream of data back to computers aboard the Oden as it is slowly lowered over the bow of the ship. Signals are sent back and forth between the CTD and the ship through a special cable that is over 2 miles long.  The conductivity of the water allows the oceanographers to infer the saltiness and by measuring and graphing the profile of changing temperature and salinity the scientists can identify specific layers in the water column.  The CTD aboard the Oden also carried sensors that measured the amount of dissolved oxygen and the movement of ocean currents.  If the seawater is extra salty or cold it is more dense and will sink.  Warmer or fresher seawater will rise.  These differences drive currents that move nutrient rich water from the ocean depths, up onto the continental shelf of Antarctica and then back down again. 

The CTD also includes a rosette of 24 bottles that are used to collect water samples as the probe comes up from the depths.  The bottles are sent down with their spring loaded tops and bottoms in the open position but when the oceanographers want a water sample from a specific depth they send a signal to the CTD and the bottles are closed, one at a time.  The oceanographic chemists and biologists on board patiently wait as the CTD descends and returns on each of its 1-4 hour trips to the bottom.  They then line up to collect the water samples that they take to their labs for analysis.  The physical oceanographers who maintain and operate the CTD work in 12 hour shifts, wearing heavy, cold weather clothing as well as hard hats and steel toed boots to protect them.  Over the course of 4 weeks aboard the Oden, they successfully launched and retrieved the CTD over 100 times!

The CTD always reminds me of an outer space probe because it can go where humans can’t go and it can bring back data and samples.    The CTD crew helped me to attach my underwater video camera to the probe by modifying the camera pole that was created by students at my high school.  Then they conducted a short 10-meter cast of the CTD that allowed me to capture some pretty cool video.  I hope you enjoy it!

Making memories on the ice!

Jeff Peneston