Steve Lambert, WHOI
August 7, 2012
We encountered our first small patch of ice last night then went through a bit this morning at about 0400. This is just stray ice and we expect open water for the next day or two. The edge of the ice pack is still quite a bit further north.
Our chief scientist, Dr. Williams from the Institute of Ocean Sciences, began taking measurements with an underway conductivity/ temperature/ depth (uCTD) instrument. The probe - pre-loaded with 500 meters of line - is attached to an electric fishing reel and cast off the stern. As the ship makes 8-10 knots to keep the line away from the screws, the reel is set to free spool paying out line as the probe dives. A short, heavier section of 800 lb test line which can take more abuse is used at the surface while the remainder is 500 lb test and pays out more smoothly. The instrument is timed and allowed to dive for approximately 2 minutes then retrieved with the electric reel. By the time 2 minutes is up and the probe has presumebly reached its depth, the ship has moved away from the test sight and now nearly 1000 meters of line must be reeled back in. The trick is to do this without smacking the CTD against the hull or, worse yet, breaking the line and losing the probe altogether and Dr. Williams did so quite easily. The purpose of this instrument is to allow scientists to take more measurements without stopping the ship (as is needed with the rosette) and the result is much more frequent sampling at a relatively low cost.
Elsewhere on the ship students from the University of Laval have made a successful CTD cast with the small rosette on the bow and the gents from the UK are making easy work of the turbulence measurements. So far everthing seems to be working well.