UNIVERSITY OF EXETER
Research news
PICTURE: SEVERAL FACTORS INFLUENCE THE VARIABILITY OF SEA CURRENT INTERFERENCES. Show More CREDIT: PROF HELEN JOHNSON
Researchers have identified the key factors that affect an important pattern of ocean currents.
The Atlantic meridional overturning circulation (AMOC) transports warm water from the tropics to the north.
Many scientists believe that this heat transport makes areas like northwest Europe and the UK warmer than they otherwise would be.
Climate models suggest that the AMOC is likely to weaken in the coming decades, with far-reaching implications for regional and global climates.
The new study – led by the Universities of Exeter and Oxford and published in Nature Geoscience – shows the causes of the monthly and annual AMOC variations and finds a different picture at two important locations.
The observation data came from extensive monitoring equipment – off the coasts of Florida and Africa and in the North Atlantic between Greenland and Scotland – operated by the international RAPID and OSNAP projects.
“Understanding the AMOC variability is challenging because the circulation is influenced by several factors, all of which vary and whose overlapping effects last for years,” said lead author Dr. Yavor Kostov from the Department of Geography at Exeter University.
“Our results show the crucial role winds play in changing this ocean circulation.
“Wind was a key factor in both the subtropical and subpolar areas that we studied.
“As the climate continues to change, more efforts should be focused on monitoring these winds – especially in key regions along the continental borders and on the east coast of Greenland – and understanding what drives them.”
While the AMOC variability off the southern United States is dominated by the influence of winds, the variability in the North Atlantic is created by the combined effects of wind, heat and freshwater anomalies. “Our reconstruction suggests that the overturning circulation in the subpolar North Atlantic is more sensitive to changes in the background state of the ocean, such as shifts in the locations of deep convection, compared to the subtropics,” said Dr. Kostov.
“This implies that future climate change can change the annual AMOC variability in this region. It underscores the need for further observations of the subpolar North Atlantic. “
The study also notes that changes in surface temperature and salinity near Canada and Greenland can have a long-range delayed effect on the Atlantic circulation as far south as Florida.
###
This study was funded by the UK Natural Environment Research Council, the National Science Foundation, the National Oceanic and Atmospheric Administration, NASA and the Simons Foundation in the USA.
The paper published in the journal Nature Geoscience is entitled: “Distinct sources of interannual subtropical and subpolar Atlantic overturning variability”.
From EurekAlert!
2.3
3
voices
Item rating
Like this:
Loading…
Comments are closed.