VARIATIONS IN SEA-ICE CONCENTRATION OF THE LONG STRAIT DURING THE SUMMER-FALL NAVIGATION SEASONS IN 1993-2018

As global climate warming progresses, the arctic ice declines thus bringing new possibilities for arctic shipping. The new transport strategy of Russia dictates rapid growth of cargo transportation along the Northern Sea Route within the next two decades, which requires constant monitoring and assessment of sea ice dynamics in the Russian Arctic. Extensive research has been done for its western part (the Kara Sea and the Barents Sea), however scarce data is available for its eastern parts including the Laptev and East-Siberian seas. The issues of safe navigation along the Northern Sea Route are considered in the paper. An emphasis is made on one of its key seaways - the Long Strait, which connects the East-Siberian and the Chukchi seas. The aim of the research is to study variations in sea-ice concentration during the summer-fall navigation seasons in 1993-2018 and identify ice hazards for vessels transiting the strait. Sea ice dynamics is studied for both 1993-2018 and 2015-2018 periods. As source data, satellite monitoring and global ocean reanalysis databases are used. GLORYS12.v1 is preferred as the main reanalysis database since it contains the most extensive data on the Arctic waters. Its results were tested prior to the research and found adequate for the task. A consistent trend for the sea ice concentration decline has been revealed throughout the strait in the summer-fall months of 1993-2018 periods. Risks of encountering sea ice with unacceptable characteristics (as per ship ice class limitations) tend to decrease everywhere. It has been shown that August, September, and October remain ice-free, hence no ice breaking assistance is needed for ships transiting the strait during this period. Situation is somewhat different in July and November. Risks of encountering dangerous ice tend to rise when navigation in westerly direction. In July, the most favorable conditions for shipping exist along the coast of the Chukchi Peninsula. This is not the case for November, when it is safer to navigate along the southern coast of the Vrangel Island. Temporal worsening of the ice situation has been revealed in the strait in 1998-2001 and 2010-2013. During these periods ice risks increase by up to 20 % for both July and November causing minor hazards for navigation therein. No such trends have been found in the most recent analyzed period - 2015-2018. The situation, however, requires to be further monitored to predict potential ice-related hazards in the future.

Long Strait, Northern Sea Route, probability, ice concentration, trend, hazard, reanalysis

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