Earth Institute Contact: Dr. William Smethie Jr.
Additional External Researchers:
Dr. John Toole, Terrence Joyce, Robert Pickart, Ruth Curry (WHOI)
Locations: Atlantic Ocean
The proposed study will build understanding of the mechanisms and rates of North Atlantic Deep Water export to lower latitudes and the relationships of varying deep water flow to the upper ocean circulation. This knowledge will help clarify the response of the ocean to variations in air-sea exchange and ultimately, the ocean's role in global climate change. The overturning circulation of the Northwest Atlantic Ocean at mid-latitude involves poleward transport of warm water by the Gulf Stream and equatorward flow of colder intermediate and deep waters. Comprehension of how these limbs of the global current system and their associated regional recirculations vary on decadal time scale is incomplete. Limiting advance in understanding is the lack of long, well-resolved records to document interannual signals in water properties, stratification, and transport of the Deep Western Boundary Current (DWBC) system. Importantly, anomalies created at subpolar latitudes may be profoundly altered or even blocked by the Gulf Stream. Conversely, subpolar anomalies may influence the position, strength, and/or stability of the Stream, and in turn affect patterns of air-sea exchange throughout the North Atlantic. This project will document temperature, salinity, tracer, and velocity variations of the DWBC upstream of its Gulf Stream cross-under point by maintaining a moored array over the slope south of Woods Hole, and occupying a hydrographic section along this line semi-annually. The array (named Station W in memory of Val Worthington) will quantify changes in DWBC water properties, stratification (potential vorticity), and transport. The high-spatial-resolution sampling possible from the ship will help verify that the array resolves interannual signals (as well as return water samples for shoreside tracer analyses). In addition to raw observations, value-added products such as time series of core properties and transport by water mass will be produced and distributed. Equally important, the project will explore whether a subset of our proposed array is suficient to index water property and transport variations in this area, setting the stage for a long-term ocean observing system. The observations proposed will explore and test theoretical ideas about the interaction of the Deep Western Boundary Current and Gulf Stream. Graduate students enrolled in the introductory physical oceanography course will participate on the proposed cruises, introducing them to observational oceanography. Moreover, the program will support one Ph.D. student whose dissertation research will focus on the acquired data. All observations and resulting data products will be expediently made available to the community via the internet with the intention of fostering widespread use of these data so that any member of the community can utilize them in their own research program.
Cross Cutting Themes:
Woods Hole Oceanographic Institute
National Science Foundation