Peculiarities of joint influence of navigation intensification and climate change on fast ice distribution in the Ob’ Bay

Abstract

All year–round navigation in the Ob’Bay has been operating for more than ten years. In recent years it has been performed most actively at three points: the port terminals Sabetta and «Utrenniy» (on the opposite coasts in the northern part of the bay) and the oil loading terminal «Vorota Arktiki» (in the southern part of the bay, off cape Kamenny). Regular winter navigation to Sabetta began in 2013 and to cape Kamenny in 2015. In recent years, the number of vessels in November–May has already risen to about 380 per season. The winter navigation in the fast ice is performed along ice channels, which should impact on the fast ice stability. The aim of this research was to determine the influence of navigation on the fast ice distribution in the Ob’Bay in terms of climate changes. To analyze navigation impact on the fast ice distribution in the Ob’Bay, data on air temperature, ice conditions and number of vessels in the winter period were used in the work. The sum of the freezing degree days (FDD) was chosen as a parameter of winter conditions severity. The mean location of the south boundary of the flaw polynya per season was a parameter of the fast ice stability. Such an approach reduced the influence of short–term fluctuations of temperature and ice conditions. The data analysis carried out over the last 25 years has confirmed a significant influence of navigation on the fast ice distribution. It has been found that for the range from mean to mild winter conditions (an estimate using FDD), the dislocation of the flaw polynya boundary in the south direction amounted to 0.4–0.8 degrees of latitude (25–50 miles) because of winter navigation intensification. Winter conditions more severe than mean have not been recorded in the region over recent years. Therefore, such estimates were not obtained for them. The discovered changes of ice conditions are significant for the region. The transfer from fast ice to drifting ice of different types, forms and concentration will lead to the corresponding restructuring of other natural processes (water dynamics, litho-dynamic regime, etc). Subsequently the impact of hydrometeorological factors on engineering facilities can change, affecting the navigation conditions, scenarios of loading on the hydraulic structures, absolute loading values, etc. This is a factor to consider in the economic development of the region.