Abstract:
Situated beneath the Arctic perennial ice pack, the principal components of the
Beaufort Gyre Observing System are three deep-ocean bottom-tethered moorings with
CTD and velocity profilers, upward looking sonars for ice draft measurements, and
bottom pressure recorders. A major goal of this project is to investigate basin-scale
mechanisms regulating freshwater and heat content in the Arctic Ocean and particularly
in the Beaufort Gyre throughout several complete annual cycles. The methods of
recovering and re-deploying the 3800 m long instrumented moorings from the Canadian
Coast Guard Icebreaker Louis S. St. Laurent in August 2004 are described.
In ice-covered regions, deployments must be conducted anchor-first, so heavier
wire rope and hardware must be incorporated into the mooring design. Backup buoyancy
at the bottom of the mooring is advised for backup recovery should intermediate lengths
of the mooring system get tangled under ice floes during recovery. An accurate acoustic
survey to determine the exact location of the mooring, adequate ice conditions, and
skilled ship maneuvering are all essential requirements for a successful mooring
recovery. Windlass (or capstan) procedures could be used for the recovery, but a traction
winch arrangement is recommended.
