jump to intro, climate, distrib, formation, types, drift, satellite, glossary, references   ARCTIC REGION SEA ICE DISTRIBUTION AND SEASONALITY   Average Arctic monthly sea ice concentration         Maximum sea ice area            13.9 million km²         Minimum Sea Ice area             6.2 million km²

        The Arctic ice cover is bounded by land as it grows southward. This strongly influences the rate and southern range of northern sea ice.  Arctic sea ice extends into lower latitudes than the Antarctic, except for an ice-free region in the North Atlantic that is fed by warm, Gulf Stream waters.
        Since the high northern latitudes are dominated by the Arctic Ocean, the northern sea ice cover is also characterized by a persistent perennial multiyear ice pack, with ~ 50 % of northern sea ice being retained throughout the summer [Gloersen, et al, 1992].  The Arctic minimum falls within a 24 day range [Gloersen, et al, 1992] around the Antarctic maximum [Gloersen, et al, 1992].

Notice that the Arctic sea ice extends into lower latitudes than the Antarctic, except for an ice-free region in the North Atlantic and the Barents Sea that is fed by warm, Gulf Stream waters. Overall trends in the sea ice concentration over the lifetime of the Nimbus 7 satellite show positive interannual trends in central Arctic Ocean and in Baffin Bay/Labrador Sea [Gloersen, et al, 1992]. Negative interannual trends have been detected in the Seas of Kara, Barents, Greenland, and Okhotsk [Gloersen, et al, 1992]. The overall ice trend in the Arctic region is -2.9% per decade [Parkinson lecture, 1998].
         The ice-free regions of the Arctic region are strongly controlled by surface temperatures of the ocean which are shown in the following image.

A persistent ice cover remains over the deep ocean basins of the central Arctic region throughout the year because low salinity surface waters inhibit the advection of heat from subsurface layers. Surface waters can maintain subzero temperatures due to the halocline and the insulating properties of the existing ice. 

Change in monthly Arctic sea ice concentration
       The following animation shows the relative change in sea ice concentration between two consecutive months. The cooler colors (greens and blues) represent regions of ice formation and the warmer colors (oranges and reds) show where ice melt dominates.  There is little overlap of decay and growth phases of the sea ice due to the strong regional forcing of the effect of continentality.

 

 
        Most of the Arctic region is covered by thick perennial ice (~3% open water), but the peripheral seas maintain 15 - 40% open water within the ice cover there [Gloersen, et al, 1992]. The thickest ice accumulations occur off of the Canadian Archipelago where ice is forced southward off of the ice pack by winds and substantial ridging compresses drift ice to thicknesses in excess of 6 meters (see the following figure) [Hibler, 1989]. from [Hibler, 1989]

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