Saturday, February 06, 2016

Absurd January Warmth in Arctic Brings Record-Low Sea Ice Extent

Figure 1: Departures from average in Arctic sea ice extent for January, 1979-2016. (Image credit: NSIDC)  Click to Enlarge.
This winter’s freezing season in the Arctic is falling short. The extent of Arctic sea ice this week is hovering near record-low values for early February, based on observations that extend back to the start of satellite monitoring in 1979.  Data from the National Snow and Ice Data Center (NSIDC) shows that last month had the lowest overall Arctic sea ice extent of any January in the satellite record (Figure 1).
Figure 2: Sea ice extent for January 2016 (white), compared to the median January location of the ice edge for the period since 1979 (magenta line). The largest areas of open water where ice is usually present are in the Barents Sea, north of Scandinavia. (Image credit: NSIDC) Click to Enlarge.As detailed in an NSIDC report on Thursday, the total extent of 13.53 million square kilometers (5.2 million square miles) was 1.04 million sq km below the 1981-2010 average and 90,000 sq km below the record from January 2011.

Only a few weeks are left before the return of polar sunshine puts an end to the freeze-up that typically starts in September and peaks in late February or March.  Last year’s maximum extent occurred quite early--on February 25--and it was the lowest in the satellite record, at 14.54 million square kilometers.  This year appears to have a reasonable shot at breaking that record.

The not-so-frozen North
Hand in hand with the skimpy ice cover, temperatures across the Arctic have been extraordinarily warm for midwinter.  Just before New Year’s, a slug of mild air pushed temperatures above freezing to within 200 miles of the North Pole.  That warm pulse quickly dissipated, but it was followed by a series of intense North Atlantic cyclones that sent very mild air poleward, in tandem with a strongly negative Arctic Oscillation during the first three weeks of the month.

“January was absurdly warm in the Arctic,” said NSIDC director Mark Serreze.  According to data from NOAA’s Earth Systems Research Laboratory, the average surface temperature in January between latitude 60°N and the North Pole was -18.2°C (-0.8°F), topping the previous record of -20.6°C (-5.1°F) set in January 2005.  Just above the surface (925 mb), the average January temperature of -14.2°C (5.9°F) was well above the previous record of -16.5°C (0.7°F), also set in 2005.  The fact that average readings at this level are warmer than at the surface reflects the strong inversion typical of the lower Arctic atmosphere, especially in winter, as cold air hugs the surface and milder air flows just above it.

Read more at Absurd January Warmth in Arctic Brings Record-Low Sea Ice Extent

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