World - Charting a course: URI professor draws Atlantic data from shipping vessels
Uses a century’s worth of data to report on Atlantic Ocean between New England, Bermuda and Africa
KINGSTON, R.I. – March 9, 2023 – Messages in a bottle often carry information from another place and time. For University of Rhode Island professor emeritus H. Thomas Rossby, the messages he’s received came from seafarers and oceanographers past, as he recently combined century-old data, and a novel way of capturing modern data, to produce a report on the Atlantic Ocean that gives oceanographers a better understanding of the Atlantic Meridional Overturning Circulation (AMOC).
Lay readers are likely familiar with the Gulf Stream, which is part of the larger Atlantic circulation system.
Both are important for study as the Gulf Stream, a sort of express lane that transfers heat from low to high latitudes. A slowing of its current would have significant impacts on weather, humans and sea life.
Whether it’s slowing or not has been widely debated for about 25 years reflecting the many different approaches people have taken to its study. While the Gulf Stream is constantly shifting and varying in strength, Rossby and collaborators find no evidence that the Gulf Stream is weakening as other studies have suggested.
Rossby and other ocean scientists perform their calculations on a large canvas, one covering Florida to Africa and Labrador to Greenland. To tackle that vast geographic landscape, the oceanography professor employed ships that already tack across these distant points to help gather data.
Rossby has long been a proponent of using seagoing vessels for science. He’s a firm believer in tangible evidence; at his retirement from full-time teaching in 2011, he holds the record for most ocean-going research on URI’s research vessel Endeavor. In his six-decade career, Rossby estimates that he’s spent a total of two years at sea for science. His view is: how can we possibly learn about the oceans without ships?
Oleander launches
Rossby set out to measure ocean currents using an acoustic Doppler current profiler (ADCP), installed on merchant marine vessels in regular traffic.
In 1992, Rossby put one in the hull of the Oleander, which sailed weekly from New Jersey as the key supply vessel for Bermuda. Rossby has long advocated for oceanographers to use merchant vessels as a way to gather needed data. Rossby says, “The Oleander offered a terrific route for us: it cuts across the shelf waters, the cold slope waters north of the Gulf Stream (from the Labrador Sea), the Gulf Stream, and the Sargasso Sea.”
He later went on to add a current profiler on the Faroes ferry Norröna (operating between Denmark, the Faroes and Iceland) and the Greenland vessel Nuka Arcticathat sailed between Greenland and Denmark. To date, the Oleander has collected more than 1,000 crossings of the Gulf Stream.
