On the record reduction in 1998 western Arctic sea-ice cover

During summer 1998, record reductions in ice cover occurred in the Beaufort and Chukchi seas. Open water formed earlier than in prior years, and Septe mber ice extent in this region was 25 percent less than the previous minimu m for 1953-1997. Seven percent of the Arctic Basin that had been perenniall y ice covered was ice-free in 1998. This reduction in western Arctic ice ex tent can be attributed in part to preconditioning by light-ice cover in aut umn 1997 and to atmospheric circulation patterns during the following winte r through autumn that favored southerly and easterly winds. Such decreases in northerly winds, and the associated weakening or displacement of the Bea ufort Gyre, is found to be typical of winters that precede years with below -normal ice extent in the western Arctic.