The layer of ice and snow that covers the Arctic Ocean and its marginal seas is highly variable in nature. Satellite imagery of the ice cover (Parkinson, 1991) has shown great interannual variability in the monthly averaged sea-ice distribution over the past 15 years. Although the central Arctic has its greatest variability in the summer, many of the marginal seas, which are ice covered in winter only (e.g., Bering Sea and the Sea of Okhotsk), exhibit the greatest variability in winter. The seasonal cycle of ice growth and decay has also been observed to vary from region to region and from year to year (Parkinson et al., 1987). On average, the ice cover in the northern hemisphere reaches its maximum extent in March and its minimum extent in September.

Preller, R.H. 1992. Sea ice prediction: The development of a suite of sea-ice forecasting systems for the northern hemisphere. Oceanography 5(1):64–68, https://doi.org/10.5670/oceanog.1992.35.

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