Pack Ice

pack ice

a large area of floating ice, usually occurring in polar seas, consisting of separate pieces that have become massed together

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pack ice [′pak ‚īs]

(oceanography)

Any area of sea ice, except fast ice, composed of a heterogeneous mixture of ice of varying ages and sizes, and formed by the packing together of pieces of floating ice. Also known as ice canopy; ice pack; pack.

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Pack Ice 

polar sea ice that has lasted through more than two annual cycles of buildup and thaw. It is usually observed in the form of vast ice fields in the Arctic Basin and as shore ice along the northern coasts of Greenland, in the northern straits of the Canadian Arctic Ocean archipelago, and in Antarctica. Hummocks in fields of pack ice are usually smoothed out by recurrent thaws, and as a result the fields tend to be rolling. Extensive pack ice makes passage by ships impossible and presents a serious obstacle to navigation along the pack’s southern margin. Pack ice accounts for 60–90 percent of the ice sheet of the Arctic basin, depending on how far south the pack ice extends.