NOAA's Ocean Prediction Center made a short silent movie of two hurricane-force storms in early March this year. These storms were two of the most intense lows to develop in this extremely stormy winter in the North Atlantic. The extraordinarily stormy weather in February and March has spun up the thermohaline circulation, draining icy, relatively fresh water from the Canadian side of the Arctic Ocean and driving warm salty water that originated in the Gulf Stream up the coast of Norway, into the European side of the Arctic Ocean. The influx of warm air and water from these storms caused Arctic sea ice to retreat and set a provisional record-low maximum on February 25, 2015.


Supplementary figure showing the intense polar vortex event associated with the extreme winter storms and Labrador sea deep convection in February and March, 2015
The polar vortex was stronger than normal in February and the first half of March, 2015. Blue from the surface to the stratosphere shows a strong polar vortex. The Polar Vortex strength for winter 2014-2015 is displayed as the geopotential height anomaly versus time for 65-90 degrees N.
The polar vortex was stronger than normal in February and the first half of March 2015. Blue from the surface to the stratosphere shows a strong polar vortex. The polar vortex strength for winter 2014-2015 is displayed as the geopotential height anomaly versus time for 65-90 degrees N.
Supplementary figures showing the surge of warm Atlantic water into the Arctic.
Warmer than normal water is flowing up the coast of Norway into the Arctic.

Warmer than normal water is flowing up the coast of Norway into the Arctic.
These two figures for March 20, 2014, and March 20, 2015, taken from the Mercator Ocean analysis of water temperatures at a depth of 1,000 feet (318 meters), show a surge of warm Atlantic water deep into the European basin of the Arctic Ocean and show the expansion of the area of cold sinking water in the Labrador Sea and North Atlantic waters.
Water temperatures at a depth of 1000 feet (318m) March 20, 2014, Mercator Ocean analysis, in and around the Arctic.
Water temperatures at a depth of 1,000 feet (318 m) March 20, 2014, Mercator Ocean analysis, in and around the Arctic.
Map of water temperature at a depth of 1000 feet for March 20, 2015. Warm Atlantic water has surged into the Arctic and cold Arctic water has drained into the Labrador sea since the same date a year ago.
attribution: Mercator Ocean
Map of water temperature at a depth of 1,000 feet for March 20, 2015. Warm Atlantic water has surged into the Arctic and cold Arctic water has drained into the Labrador sea since the same date a year ago.