Friday, May 11, 2007

Oceanography: Oceanic short circuit

Researchers have discovered a 'short circuit' in the circulation of the world's oceans that allows cold waters that sink to the abyss to return to the surface more rapidly than previously thought. Understanding oceanic circulation is important because it transports heat, carbon and nutrients around the globe and therefore plays a central role in Earth's climate.
Ocean mixing in the current that flows around Antarctica has a key role in global ocean circulation as it influences the rate at which water sinking to the deep ocean at high latitudes returns to the surface in the Southern Ocean. But the rates of mixing processes that occur in the current and the induced upwelling are not well known. Alberto C. Naveira Garabato and colleagues studied the spread of helium released from submarine volcanoes to measure the rates of mixing and upwelling in the southwest Atlantic sector of the current.
Their results indicate that the rough topography of the ocean floor in this region leads to both rapid mixing across density surfaces and rapid upwelling along density surfaces, which together create a 'short circuit' in the global oceanic overturning circulation.
CONTACT
Alberto C. Naveira Garabato (University of Southampton, UK)
Tel: +44 23 8059 2680; E-mail: acng@noc.soton.ac.uk

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