ИСТИНА

Ice season start and end dates and duration are investigated in the White Sea region using modern historical (from 1978 to 2016) and high-resolution (10-km) satellite sea ice products. This work was carried out with the purpose of primary collection of ice cover state information (ice season duration) on the Winter coast of the White Sea to substantiate the construction of the port near the place Kuya (about 50 - 60 km to the north from Arkhangelsk). The main question of the research is "Are the ice conditions near the Kuya settlement more favorable for navigation if compared to Arkhangelsk port in terms of ice period duration and how much?” As far as sea ice observation data are scarce and expensive in this region, satellite products give a nice opportunity to set sea ice investigation. Reprocessed global sea ice concentration data records, distributed by OSISAF [1], were used as input data for the analysis. This dataset covers period from 1978 to 2016 with spatial resolution of 10 km. The long period coverage and relatively high resolution sets apart this product from the others which might have higher resolution but short time-series (usually from 2000s) or long series but coarse resolution (about 30-40 km). Long-term and annual values of sea ice season duration with start/end dates were determined for three sites over the Dvinskaya Bay «Zimnegorskiy» (north), «Kuiskiy» (middle) and «Mudiug» (south and close to Arkhangelsk). Considering the limitations of sea ice satellite information usage in near-shore zones the original algorithm for sea ice season start/end dates detection was developed. It allows to determine three key time points: start of ice period (sea ice manifestation), start of severe ice period (sea ice with 70-90% concentration) and end of sea ice season. It is revealed basing on the OSISAF data product, that ice period duration near Kuya is by at least 14 days shorter than in the Severnaya Dvina river mouth and and by 14 days longer, than in Zimnegorskiy Mayak site. Also has been decreasing by 20-30 days (10-20%) since 1978.