AGU: Geophysical Research Letters

 

Editors' Highlight

Warmer surface temperatures in the North Atlantic may affect the mighty current that encircles Antarctica

In the North Atlantic Ocean, cold salty water sinks, forming the North Atlantic Deep Water, a southward moving water mass centered around the depth of 2.5 km. This down-welled water is replaced by water essentially originating in the Antarctic Circumpolar Current and flowing across the equator northward through the surface currents, such as the Gulf Stream and the North Atlantic Current. To understand relationships among these currents, Fučkar and Vallis (2007) conducted a sensitivity study using a coarse-resolution ocean general circulation model in an idealized single-basin configuration with a circumpolar channel. They found that as surface temperature increases in the north, deep water production diminishes, affecting the basin's overturning circulation and stratification. This induces a change in the water mass properties in the southern circumpolar region, causing a substantially higher volume transport around Antarctica. The authors noted that significant variations in certain critical model parameters do not change this result. If their model holds true, then a change of surface buoyancy conditions in the Northern Hemisphere may significantly influence the stratification and transport of the Antarctic Circumpolar Current.

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