Dispatch 13: Re-deployment of Mooring B     Print

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Mengnan Zhao

September 30, 2015

Today, we continued with yesterday’s mooring work. After making repairs, changing batteries and testing instruments, we re-deployed Mooring B in the same spot: 150W, 78N, on the northwestern side of the Beaufort Gyre and to the northeast of the Northwind Ridge and Chukchi Borderland region. This region has the most complicated sea-floor topography in the entire Canada Basin region, and related to this are many energetic ocean processes that can be measured by the mooring. I recently submitted a paper with my adviser (Mary-Louise Timmermans) investigating some of these processes (ocean eddies) by analyzing the measurements from Mooring B taken since 2003. Before coming on this expedition, the mooring location was just a latitude and longitude in my head, but now observing the mooring deployment into the deep ocean below, and thinking about the possibility of an eddy slowly passing by felt awesome!

The method of mooring deployment was backward to the recovery – from bottom to top. It was a huge load on the supporting winches, not only due to the long mooring wire (over 3800 m), but also the many instruments that needed to be attached to the wire as it went over the side of the ship. The entire deployment took nearly 5 hours. The heavy anchor with the Bottom Pressure Recorder (BPR), and the two acoustic releases (needed for the recovery) were first to go over the side of the ship. Following this, groups of 50 floatation balls are added. This had to be very carefully done because of the heavy anchor already over the side, with two winches and our super John Kemp (who continued to impress me by working with his bare hands from time to time) and Boatswain Ricardo Amamio. It was a grand view with so many floating balls being lifted high before being sent into the water, reminding me of a lantern string during spring festival in China. Then came the MicroCAT, sediment trap, transponder/MicroCAT for tracking locations and temperature and salinity, and the floatation sphere we introduced in the last dispatch. It was the coldest day we’ve had yet with temperatures reaching -12C, strong winds and nearly horizontal snow. I couldn’t feel my fingers after taking photos even though I was fully layered with small heating bags borrowed from Wes. After the mooring was successfully deployed, there was a feeling of great accomplishment and everyone on the fore deck had big smiles on their faces.

The evening was made interesting by an activity to decorate styrofoam cups which would be sent down with the rosette to great depths (thousands of meters) in the ocean, and shrink to a fraction of their size under the pressure. I was also excited to learn from Chief Scientist Bill Williams that Rick discovered in the new Mooring B data that the mooring had been dragged deeper (up to 270 m!) just a week before our recovery. This may have been caused by a huge fast eddy. I can’t wait to learn more.

The day ended with a celebration of Deo’s birthday in the bar. The guitar performances by Third Officer Ada Manning, Second Officer Mark Gould, Cadet Geoffrey Oliver, Nurse Edith Jobin and Wes were amazing.