A wintry mix from a dynamic cryosphere - NSIDC

Arctic sea ice extent for January 2013 was well below average, largely due to extensive open water in the Barents Sea and near Svalbard. The Arctic Oscillation also remained in a primarily negative phase. Antarctic sea ice remained extensive due to an unusual northward excursion of ice in the Weddell Sea. December of 2012 saw Northern Hemisphere snow cover at a record high extent, while January 2013 is the sixth-highest snow cover extent on record since 1967.

Figure 1. Arctic sea ice extent for January 2013 was 13.78 million square kilometers (5.32 million square miles). The magenta line shows the 1979 to 2000 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data  Credit: National Snow and Ice Data Center 

The average sea ice extent for January 2013 was 13.78 million square kilometers (5.32 million square miles). This is 1.06 million square kilometers (409,000 square miles) below the 1979 to 2000 average for the month, and is the sixth-lowest January extent in the satellite record. The last ten years (2004 to 2013) have seen the ten lowest January extents in the satellite record.

As has been the case throughout this winter, ice extent in the Atlantic sector of the Arctic Ocean remained far below average. While the Kara Sea was completely iced over, nearly all of the Barents Sea remained ice free, and open water was present north of the Svalbard Archipelago. The lack of winter ice in the Barents Sea and the vicinity of Svalbard has been a common feature of recent years. Recent work by Vladimir Alexeev and colleagues at the University of Alaska Fairbanks provides further evidence that this 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.

Also, a new paper by Jinlin Zhang and colleagues at the University of Washington analyzed the effect of the strong August 2012 cyclone on last year’s record sea ice minimum. While they found a large effect in the immediate wake of the storm, the effect declined quickly and overall it had only a small effect on the final September minimum extent.

Figure 2. The graph above shows Arctic sea ice extent as of February 4, 2013, along with daily ice extent data for the previous five years. 2012 to 2013 is shown in blue, 2011 to 2012 in green, 2010 to 2011 in pink, 2009 to 2010 in navy, and 2008 to 2009 in purple. The 1979 to 2000 average is in dark gray. The gray area around this average line shows the two standard deviation range of the data. Sea Ice Index data. Credit: National Snow and Ice Data Center 

Through the month of January, the Arctic gained1.36 million square kilometers of ice (525,000 square miles), which is slightly higher than average for the month. Air temperatures at the 925 hPa level were 2 to 5 degrees Celsius (4 to 9 degrees Fahrenheit) higher than average across much of the Arctic Ocean. Conditions were especially warmer than average near Svalbard where ice-free conditions persist. 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.

Figure 3. Monthly November ice extent for 1979 to 2013 shows a decline of -3.2% per decade. Credit: National Snow and Ice Data Center

Average Arctic sea ice extent for January 2013 was the sixth lowest for the month in the satellite record. Through 2013, the linear rate of decline for January ice extent is -3.2 percent per decade relative to the 1979 to 2000 average.

Source: nsidc.org