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Images: Signs of Big Change in the Arctic

Arctic climate is regulated by an intricate series of interconnected mechanisms that shift winds, ice, currents, and other conditions. In the recent past, the Arctic had reliably shifted between high-pressure clockwise (left) and low-pressure counterclockwise (next image) wind-driven circulation regimes. But global warming may be causing the system to stick longer in the clockwise high-pressure mode.During the high-pressure phase, the Arctic is cold and dry and dominated by high atmospheric pressure that sets in motion strong anticyclonic (clockwise) winds over the Beaufort Gyre region. The winds drive the powerful clockwise-circulating Beaufort Gyre. The cold thickens sea ice. The gyre encircles a huge reservoir of sea ice and fresh water that drains into the region from many big northern rivers and the Bering Strait. The gyre corrals this pool of ice and fresh water, preventing it from flowing southward into the North Atlantic Ocean. (Illustration by Eric S. Taylor, Woods Hole Oceanographic Institution)
During the low-pressure phase in the Arctic, cyclonic storm systems that form in the North Atlantic move up into the Arctic, bringing heat and moisture. The Arctic atmosphere becomes relatively warm and humid. Atmospheric pressure decreases, causing winds to reverse. The gyre weakens and its circulation turns counterclockwise. The huge pool of trapped sea ice and fresh water then leaks out and flows out of the Arctic Ocean and into the North Atlantic. This creates a layer of cold but less dense water that caps the surface of some parts of the North Atlantic. The layer blocks heat from the ocean from escaping into the atmosphere and tempering wintertime climate in the North Atlantic region.
The gears continue to turn. Colder sea-surface temperatures in the North Atlantic provide less heat to fuel cyclones. Fewer cyclones form to penetrate the Artic, and so the region eventually shifts back to being cold and dry and dominated by high pressure that cranks up the Beaufort Gyre again.

(Illustration by Eric S. Taylor, Woods Hole Oceanographic Institution)
WHOI researcher John Kemp is lowered in a basket from a ship to retrieve a buoy that measures Arctic air-sea-ice interactions, during operations for the Beaufort Gyre Exploration Project. (Chris Linder, Woods Hole Oceanographic Institution)

WHOI physical oceanographer Andrey Proshutinsky has called the remote Beaufort Gyre in the Arctic Ocean the flywheel of the Arctic climate system. He has led a long-term effort to study the gyre since 2003.

(Tom Kleindinst, Woods Hole Oceanographic Institution)
Rick Krishfield, s senior research specialist at WHOI, has spent many summer days in the Arctic Ocean, deploying and recovering scientific instruments to monitor ocean and climate conditions, as part of the Beaufort Gyre Exploration Project. (Chris Linder, Woods Hole Oceanographic Institution)
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