Ocean current with short circuit

Researchers discover oceanic circulation pump in front of South America

Ocean currents around the Antarctic NOAA
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The noble gas helium, emanating from submarine volcanoes, has helped scientists to make a discovery in the Southern Ocean. As reported in the journal Nature, there is a hitherto unknown "short circuit" in the ocean current flowing around the Antarctic. This also affects the global circulation and thus the entire climate system.

The circulation in the Southern Ocean plays a crucial role in the water and heat exchange of the oceans. For the huge "circulating current" that flows around the Antarctic connects the seas, which are separated from each other by the land masses in the north. At the same time, water is also exchanged between the deep sea and the superficial layers in this region.

Key factor in the climate system

Exactly this exchange of water is also considered to be a decisive factor in the climate system, because here, among other things, cold deep water returns to the warmer surface and this process circulates large quantities of carbon and nutrients. "The South Ocean is the least understood part of the world's oceans, but at the same time one of the most important, " explains Alberto Naveira Garabato of the National Oceanography Center in Southampton. "We need to understand the circulation that is taking place before we can make reliable predictions about the climate changes of the next 100 years."

"Circulation pump" in South America

Together with colleagues, Garabato has investigated the currents around the Antarctic using an unusual method: they followed the path of the helium gas that is ejected from volcanic deep-sea channels in the Pacific Ocean. The gas dissolves in deep water and migrates along the Chilean coast to the southern tip of the American continent. Here, at Cape Horn, it is fed into the Antarctic Circular Current and transported eastward into the Atlantic Ocean.

However, the helium path also revealed that there is a "short circuit" in the south polar current: it turned out that much of the water does not flow around the Antarctic, but that much of the vertical circulation takes place even before the tip of South America. Here, in a small marine area south of the Falkland Islands, cold deep water rises much faster to the surface than previously thought. As a "circulation pump", this region thus plays a key role in global circulation. display

(University of East Anglia, 11.05.2007 - AHE)