| Summary: | The focus of this project is on the variability of circulation, water mass properties and freshwater distribution in a region that lies north of the Canadian Archipelago and Greenland, extending from the continental shelf into the central Arctic Ocean. This region is just upstream of the freshwater exit points to the North Atlantic Ocean in Nares Strait and Fram Strait. There is evidence that circulation in this region is highly variable on interannual time scales, which may be tied to large-scale climate signals such as the Arctic Oscillation, and results in variability in the export of fresh water to the North Atlantic. This region is covered by thick ice and is difficult to reach by icebreaker, so aircraft operated out of the Canadian military base at Alert are used to perform an annual hydrographic survey for temperature, salinity and chemical properties in this region of the Arctic Ocean. The backbone of the survey is a line of conductivity, temperature and depth (CTD)/rosette stations extending from the continental shelf to the North Pole taken from Twin Otter aircraft using a modular CTD/rosette system that is lowered through a 12" diameter hole drilled in the sea ice. This system is also used to take a few stations east and west of the line, time permitting. Up to 12 water samples are collected at each station between the surface and about 700 m depth. CTD only stations are taken by helicopter and Twin Otter aircraft to provide broader spatial coverage of the region and finer spatial resolution at the continental slope. A single water sample at 1-2 m depth is taken at each of these stations. The continental shelf to North Pole section is carried out by Lamont-Doherty Earth Observatory and the broader scale survey by the University of Washington. This survey is closely coordinated with the Twin Otter survey carried out by the North Pole Environmental Observatory program each year.
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