St. Laurent compared the flow of seawater through underwater gullies in the Mid-Atlantic Ridge to the wind, so familiar to hikers, that blows through mountain passages on land.
That wind creates a condition known as turbulence, which can blow the hat from your head, St. Laurent said. In the ocean, turbulence is produced when water flows quickly though oceanic passages. The turbulence stirs the almost freezing-water near the bottom with warmer water that is closer to the surface much as you would mix cream into coffee by stirring it with a spoon.
We know that the mixing of warm surface water with very cold deep water is one of several factors that influence the Earth's climate, he said. The mixing we observed and measured for our study allows the warmth at the surface of the ocean to diffuse deep into the sea. The overall balance between warm and cold water in the Atlantic helps control the strength of the Gulf Stream, which moves heat away from the Earths equator toward regions that receive much less heating from the suns rays.
St. Laurents co-principal investigator and co-author was Andreas M. Thurnherr, a former postdoctoral researcher in the FSU oceanography department and now a scientist at Columbia University. The field study took place in August 2006 during a three-week expedition aboard a French research vessel to a location close to the Azores, volcanic islands 2,000 miles east of the U.S. and west of Europe that comprise an above-sea portion of the mostly submerged Mid-Atlantic Ridge.
To measure the energy generated by the extraordinarily intense turbulence more than a mile below the oceans surface, St. Laurent and crew used a custom-made instrument called the "turbulence profiler," outfitted with special sensors.
The turbulence profiler measured the output using watts, the same unit of measurement as printed on light bulbs, St. Laurent said. In the undersea mountain passage where we intentionally
'"/>
Contact: Louis St. Laurent
stlaurent@ocean.fsu.edu
850-644-0846
Florida State University
9-Aug-2007