Eddies drive section of thermohaline circulation

Jul 06, 2012
Eddies drive section of thermohaline circulation

(Phys.org) -- Giant currents that traverse the world’s oceans may not be as stable as previously thought after researchers found a branch of one of these global currents was powered and steered entirely by eddies, one of the oceans smallest features.

In a recently published study, Centre of Excellence Associate Researcher, Dr Erik Van Sebille, found that a cold and deep current which travels east across the Atlantic from The Americas to South Africa is directly controlled by warm-core Agulhas rings – that form at the Cape of Good Hope and migrate in exactly the opposite direction of the deep current.

The area of the ocean global overturning circulation that is affected is part of the deep branch of the global overturning circulation that flows southward across the Atlantic. The most prominent feature of this southward pathway is a deep current that is attached to the eastern shoreline of the Americas. Around 25S this deep current forks, with the majority of the water continuing its southbound journey and a smaller ribbon veering to the east and South Africa.

This video is not supported by your browser at this time.
An animation showing the movement of ocean particles to the Agulhas region near the Cape of Good Hope. Animation: Dr Erik Van Sebille.

Researchers had known for decades about this eastward current, but little was known about what drives it. Using a fine-resolution global ocean circulation model, Van Sebille et al found that the deep eastward flow across the South Atlantic is driven and steered by Agulhas rings.

The authors used simulated floats to track the three-dimensional pathway of the deep, eastward pathway across the South Atlantic and found that this pathway lines up perfectly with the path of the Agulhas rings flowing in the opposite direction. This finding gave the authors a hint as to how the two are connected, and a mathematical expansion of the laws governing the circulation confirmed that the north-westward flowing Agulhas rings at the surface force the deep flow eastward by squeezing it from above.

This finding suggests that when the number of Agulhas rings changes, this might directly affect the deep branch of the global overturning circulation.

Explore further: Radioisotope studies show the continental crust formed 3 billion years ago

More information: Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007684 , 2012.

Related Stories

How the Pacific Ocean leaks (w /Video)

Apr 17, 2012

A state-of-the-art ocean model has been used in a new study to conduct the first detailed investigation of oceanic water flow between the Pacific and Indian Oceans via the south of Australia. 

Call for network to monitor Southern Ocean current

Aug 17, 2007

The senior science advisor to the World Climate Research Programme (WCRP) has called for the establishment of a Southern Hemisphere network of deep ocean moorings to detect any change in ocean circulation ...

Salty oceans provide early warning for climate change

Jun 08, 2007

Monitoring the saltiness of the ocean water could provide an early indicator of climate change. Significant increases or decreases in salt in key areas could forewarn of climate change in 10 to 20 years time. Presenting their ...

Massive Southern Ocean current discovered

Apr 26, 2010

(PhysOrg.com) -- A deep ocean current with a volume equivalent to 40 Amazon Rivers has been discovered by Japanese and Australian scientists near the Kerguelen plateau, in the Indian Ocean sector of the Southern ...

Recommended for you

ESA image: Northwest Sardinia

Jul 03, 2015

This image over part of the Italian island of Sardinia comes from the very first acquisition by the Sentinel-2A satellite.

Experiments open window on landscape formation

Jul 02, 2015

University of Oregon geologists have seen ridges and valleys form in real time and—even though the work was a fast-forwarded operation done in a laboratory setting—they now have an idea of how climate ...

NASA image: Canadian wildfires continue

Jul 02, 2015

Canada is reeling from an early fire season this year as dozens of fires ravage at least three provinces of the country. All of the following reports are as of July 2, 2015.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jul 06, 2012
Aw c'mon, you're scaring us! What if the North American currents were so fragile ... or the Gulf of Mexico currents?

We're living on a razor's edge these days.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.