Ice conditions of navigation during the NABOS-2021 expedition in September-October 2021

The short message presents the primary processing data results of special shipborne ice observations during the NABOS-2021 expedition in September-October 2021. A feature of this expedition was unforeseen during the planning period hard ice conditions, which made adjustments to the initial expedition plans. The overall research area for the cruise included northern parts of the Laptev and the East Siberian seas within 79-82°N up to 170°W. Generalization and analysis of the sea ice conditions along the oceanographic sections were performed, combining or dividing segments in accordance with the ice conditions homogeneousness. In general, 66% of the ship track within the ice during the NABOS-2021 expedition had the ice concentration of 10 tenths, the residual ice by the route accounted for 26%; young ice,38%; the nilas and the new ice, 36%.The residual ice thickness varied from 30-50 cm to 160 cm and above, in some cases (hummock formations) over 300 cm. Residual ice thickness of 30-50 and 50-70 cm accounts for 9% each of the route length, thickness over 70 cm account for 8% of the entire route of the vessel in the ice.