| Description: | 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 obtain data and water samples by lowering a CTD and a small diameter modular rosette through a hole drilled in the ice. Annual hydrographic surveys are carried out using two types of aircraft, a helicopter to obtain close spaced stations across the shelf break and down the continental slope using only a CTD (University of Washington) and a twin otter fixed wing aircraft to obtain courser spaced stations with a CTD/rosette system in the interior (Lamont-Doherty Earth Observatory). The backbone of the survey is a line of stations extending from the continental shelf to the North Pole and stations are taken to the east and west of this line, time permitting. This survey is closely coordinated with the twin otter survey carried out by the North Pole Environmental Observatory program each year. The Lamont-Doherty Earth Observatory measurements are reported here. A Seabird SBE-19 CTD with a SBE-43 oxygen sensor was used to obtain the measurements. Data include pressure, depth, in situ temperature, potential temperature, salinity, density and dissolved oxygen. |
