Along with the ice extent and thickness, an important characteristic of the ice cover is its concentration. Ice cover concentration is an important factor for ice navigation and in the exchange of energy between the ocean and the atmosphere.
Zakharov (1996) shows that ice concentration in the Arctic Seas changes significantly during the summer season. In the basin itself, changes in ice concentration are not greater than fractions of a percent, on average (Vowinchel and Orvig, 1973), although in some limited areas they can increase significantly in some years. Specific characteristics of different concentrations of ice area in the Arctic Seas and their causes are considered in Gudkovich and Zakharov (1998).
Ice concentration in these seas varies significantly with climatic changes. Zakharov (1996) presents charts showing average changes in ice cover concentration at the beginning of September from the last decade of Arctic warming (1930-1940s) through the following cooling period. These charts show a significant increase in ice cover concentration in the northeastern Kara Sea during the cooling epoch.
Smolyanitsky (2003) used the same approach for gridded fields of sea ice total concentration as that described in Section 3.1 for MY partial concentration. Figure 3.5 (see color section) charts the changes in average ice cover concentration in the Arctic Seas from the 1940-1962 warm epoch to 1963-1983 cold epoch.
The upper part of the figure characterizes the first half of June, when the changes in the Barents Sea are better expressed, and the lower part characterizes the middle of August, when the changes are more pronounced in the Siberian shelf seas. As the figure shows, there was a significant increase (more than 4-5 tenths) in ice cover concentration from the warm to the cold epoch in the northeastern areas of the
Barents and Kara Seas, in the Pechora Sea, and also in the central East Siberian Sea and to the north of the Chukchi Sea (more than 3-4 tenths). In the Laptev Sea, a small decrease in average concentration is noted, which may be connected with elevated ice export from this sea during cold epochs as compared with the warm epochs (see section 4.4).
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