Region of vigorous ocean mixing located

The world’s oceans act like large-scale conveyor belts. In the Atlantic, for example, warm water makes its way from equatorial regions to the poles, where, cooled by the frigid surroundings and salted by the formation of sea ice, it loses its buoyancy and sinks to the ocean floor. The cold “bottom water” then heads toward the equator. To keep the conveyor moving, the bottom water must be brought back to the surface or, equivalently, be mixed with warmer, shallower water. But how? Winds can drive upwelling, as can the sloshing back and forth of bottom water over rough topography. But winds can’t do the job by themselves, and significant mixing has been detected so far in only a few, relatively small regions. Now, a team from the University of East Anglia in the UK has discovered an extensive region of vigorous mixing in the Scotia Sea, an area of rough topography that lies between the Antarctic peninsula and Tierra del Fuego. Their findings, based on in situ measurements of salinity, temperature, density, and current, suggest that the Scotia Sea could play a significant role in balancing global ocean circulation. (K. J. Heywood, A. C. Naveira Garabato, D. P. Stevens, Nature 415 , 1011, 2002 http://dx.doi.org/10.1038/4151011a .)