Dispatch 7: Day of Recovery!     Print

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Mengnan Zhao

September 24, 2015

We had gone through 7 CTD stations by this morning. Everything was according to routine and the workings of the CTD sampling team became smoother and smoother. Just when I thought today would be uneventful as usual, I was extremely excited to learn that several ice buoys would be recovered later today; especially as I have been analyzing data from these systems in my past three years of graduate study.

During the 2013 BGOS cruise, 6 buoys were deployed on one multi-year ice floe – an Ice Tethered Profiler (ITP number 70), an Ice Tethered Micro system (ITM 3), an O-Buoy, an Arctic Ocean Flux Buoy (AOFB), an Ice Mass Balance Buoy (IMBB) and a wave buoy. Some of them were continuing to report GPS locations, while others had stopped transmitting. We would be only depending on luck to recover all of them, especially those (like the AOFB) that had stopped reporting.

Around noon time, with great luck, the AOFB appeared in our sights from the ship. It was nestled in the center of a large ice floe, seemingly unharmed. The Louis gently adjusted her position to find her way to the buoy – it was challenging because we needed to break the ice floe to get very close to the buoy, while at the same time not damaging it. Our Louis (and the officers on the bridge) did an excellent job and soon the buoy was right next to the ship surrounded by loose ice. Two winches were prepared to recover it, with great help from the crew. One winch sent John Kemp, a member of the WHOI team, in a small basket to the buoy, where he hooked the buoy to the cable from the second winch. After John was lifted up, the second winch hoisted the buoy out of the ice and onto the deck.

As soon as the buoy was on board, Rick Krishfield, Jeff O’Brien and Andy Davies (members of the WHOI team) together with John quickly disassembled it so that all parts could be moved for storage. I was impressed by their efficiency and dedication; the work was done so expertly, and sometimes they used only their bare hands – on such a cold and windy day that my safety hat was once blown off my head.

The second buoy recovered today was the O-Buoy, which measures the ozone in the Arctic atmosphere. The whole procedure went very smoothly, except that the edge of the buoy was slightly bitten by a polar bear! We could even see paw prints in the snow leading up to the buoy.

Soon we were on the site of ITP 70 and ITM 3. ITP 70 had stopped working, but the ITM was still returning good data via satellite. We tried to recover the ITP while leaving the ITM nicely in the ice. The Louis and the bridge again did an exceptional job, releasing ITP 70 from the floe into open water, while leaving the ITM in the ice. However, a problem came up right after this – the ITP 70 surface buoy, instead of floating with the waves, oscillated around one position. Since both the ITP and ITM had extended tethers down to around 700 m into the ocean, Rick and Jeff guessed that the tethers from these two buoys might be tangled together, which turned out to be a wise guess. In the end we recovered both of them.

The final two buoys, on the other hand, were not so lucky – they had stopped transmitting position information and were separated from the four buoys we recovered. Hopefully, they might be found and recovered on future cruises, but for now they would continue enjoying their journey in the Beaufort Gyre.