William M. Smethie, Jr. (firstname.lastname@example.org), Columbia University/LDEO
Peter Schlosser (email@example.com), Columbia University/LDEO
Ronald Kwok (firstname.lastname@example.org), NASA/JPL
The proposed research will document the circulation, variability, and driving mechanisms of the upper ocean in the "freshwater switchyard of the Arctic Ocean." This unexplored region lies to the north of the eastern Canadian Archipelago and Greenland, extending about 500-800 km into the central Arctic Ocean. It lies just upstream of the freshwater exit points in Fram and Nares Straits, i.e., where freshwater from various sources is finally delivered to some of the main channels that lead to the North Atlantic Ocean. Evidence suggests that the circulation in this region is highly variable on interannual time scales, and that this variability might correlate with large-scale climate signals such as the Arctic Oscillation. However, the mean circulation, interannual variability, and physical processes that govern the circulation of this area are presently unknown. Our main hypothesis is that this area is a bifurcation point for freshwater transfer between the Arctic and North Atlantic Oceans, and that small changes in the overall circulation of this region may have large downstream effects.
We propose to perform observations of ocean temperature, salinity, currents, and geochemical freshwater tracers such as oxygen, oxygen isotopes, tritium/3He, CFC's, barium, and nutrients. The focus will be on the upper ocean (0-300 m) where freshwater resides. This will be an aircraft-based operation, because thick sea ice prevents access by most surface ships and political realities prevent access by submarine. Two different aircraft will be used to sample the physically relevant scales. (i) A helicopter will make a high-resolution 120 km long CTD, XCP, and limited geochemical tracer section across the North American undercurrent that flows eastward at about the 500 m isobath. (ii) A Twin Otter fixed-wing aircraft will complete two CTD and tracer sections from the coast, one of which will terminate at the North Pole. To measure tracers, we propose to build a compact CTD/rosette system with six 3L bottles and a Seacat CTD that can be deployed through a 12" hole in the sea ice. Filled rosette bottles will be transported to a land base camp for nightly sample processing, thus saving time-on-station and allowing for occupation of more stations per day. We view the rosette as new technology that can be used in other arctic studies, and our overall aircraft sampling strategy as a possible prototype for future SEARCH activities. We also plan a satellite-based study of sea ice motion and thickness in the switchyard region, in which we will determine how much ice recirculates westward within the Beaufort Gyre, how much exits through Fram Strait, and how much exits within the various passages of the Canadian Archipelago.
Results from this study will be made available via an internet web site that will be linked to other similar ongoing projects, as well as through presentations and articles in both scientific and popular formats. Additionally, they will be used for educational purposes through involvement of both graduate and undergraduate students, and in course material. A special link to numerical modeling studies is planned via incorporation of our data into a gridded ocean data base as well as raw validation data.
Our proposed study completes an overall "freshwater jigsaw puzzle" of projects that are either firmly planned or proposed. The appropriate logistics infrastructure at NSF has been developed over the past several years as part of various projects, in particular the North Pole Environmental Observatory, an aircraft-based project staged out of Alert/Eureka. The project meets Goal 1 of the ARCSS announcement of opportunity, Arctic Freshwater Cycle: Land/Upper-Ocean Linkages, by implementing an observation system that takes advantage of innovative technological advances (CTD/rosette system) that can serve as prototypes for long-term efforts to document and understand freshwater variability in the arctic.
Science Management Office
Role of the Arctic-CHAMP Science Management Office