Abstract: Data obtained from AMSR-E and AMSR-2 were used to calculate the extent of Arctic sea ice and to determine sea ice distributions for June–September from 2003 to 2014. Little difference was found between the extent of sea ice in 2014 and the mean 2003–2013 distribution. However, two apparent differences were found between the spatial distribution of sea ice in 2014 and the median 2003–2013 extent. (1) Sea ice in the Laptev Sea was obviously less than the median extent, and the sea ice boundary was higher than 85°N in September. (2) Sea ice extent in the northern Barents Sea was greater than the median extent, and the sea ice boundary expanded during summer 2014. The air pressure field in summer 2014 caused southerly winds over the Laptev Sea and northerly winds over the Barents Sea. The southerly winds brought warmer air, which promoted sea ice melting and forced the sea ice boundary to retreat northward. The northerly winds brought colder air, which reduced sea ice melting and forced the sea ice to drift southward. This resulted in a greater amount of sea ice in the northern Barents Sea. The Northeast Passage is generally navigable from early August to early October in Severnaya Zemlya. The time of opening of the Northeast Passage in the New Siberian Islands and adjacent sea regions is earlier than in Severnaya Zemlya and it closes later. Therefore, the navigability of the entire Northeast Passage depends on sea ice conditions around Severnaya Zemlya.

Key words: Arctic, sea ice extent, Laptev Sea, Barents Sea, Northeast Passage