Antarctic sea ice extent remains above average
By Summit Voice
SUMMIT COUNTY — Although Arctic sea ice cover has grown quickly the past few weeks, the extent remained below the previous record low for a full 40 days before recently climbing back to near that 2007 level on Oct. 6.
According to the National Snow and Ice Data Center, sea ice extent had grown to about 2 million square miles as of Oct. 15, which is about 1.35 million square miles below the 1979 to 2000 mean. Ice extent is growing by about 38,600 square miles per day, expanding southward at the ice edge, as well as northward from the Arctic continental coasts
Despite the rapid growth of the sea ice extent in the past few weeks, vast areas of open water remain, resulting in a massive heat transfer from the ocean to the atmosphere, with potential impacts on atmospheric circulation in high latitudes, as the heat buildup over the Arctic changes pressure gradients in the region.
The strong warming in the highest latitudes, known as Arctic amplification, has been especially pronounced this year. Air temperatures across almost the entire region have been above average continuously for the past 30 days, with the warmest conditions over northwestern Canada and extending into the Beaufort Sea, where the warm air above the ocean has been enhanced by southerly winds.
According to the NSIDC, the warming caused by the ocean and the southerly winds are linked to a pattern of unusually high pressure centered over the Gulf of Alaska. That so-called Arctic dipole anomaly has become more common in recent years, according to research led by NOAA’s James Overland of the National Oceanic and Atmospheric Administration and Jennifer Francis of Rutgers University.
The pattern of high pressure over the northern Beaufort Sea and Greenland and unusually low pressure over northeastern Eurasia and brings in warm, southerly winds along the shores of the East Siberian and Chukchi seas, leading to rapid melting of the sea ice. The pattern also pushes the ice away from the coast, out of the Arctic Ocean and into the North Atlantic through Fram Strait.
Meanwhile, Antarctic sea ice dropped back below record levels but remains well average for this time of year, but not on a scale that’s comparable to sea ice losses seen in the Arctic recently. Get the full update at the NSIDC Arctic sea ice web page.