Northern hemisphere snow cover above average in December and January
By Summit Voice
FRISCO — Arctic sea ice remained well below average during January, about 400,000 miles below the 1979 to 2000 average for the month and the sixth-lowest during the satellite record. The last ten years (2004 to 2013) have seen the ten lowest January extents in the satellite record.
According to the latest update from the National Snow and Ice Data Center, January sea ice extent has been decreasing at abou 3.2 percent per decade. The largest areas of open water were around the Barents Sea and near Svalbard, northeast of Greenland. Sea ice extent was also below average along the east coast of Greenland.
Ice experts said nearly all of the Barents Sea has remained ice free so far this winter, similar to conditions in the past few years. Recent research by Vladimir Alexeev and colleagues at the University of Alaska Fairbanks suggests the absence of ice is related to a stronger inflow of warm waters from the Atlantic as compared to past decades.
On the Pacific side, the ice edge in the Bering Sea continued to extend slightly further to the south than usual. Air temperatures over much of the Arctic Ocean stayed betwen 4 and 9 degrees above average for the month, with warmer conditions centered near Svalbard. Despite those temps, sea ice extent grew by 525,000 square miles, a pace slightly higher than average for the month.
Below average temperatures characterized parts of northern Eurasia and northwestern Canada. The dominant feature of the Arctic sea level pressure field for January 2013 was unusually high pressure over the central Arctic Ocean, consistent with a predominantly negative phase of the Arctic Oscillation.
While sea ice extent remained below average, winter snow cover in the northern hemisphere remained high. After setting a December record, the January snow cover ended up as the sixth-highest on record. Snow cover was higher than average throughout much of the western United States as well as northern Europe and eastern China. Snow cover was lower than normal over the central U.S., and much of southern Asia, including the Tibetan Plateau.