Dates When Seas Open and Close for Ice-Free Navigation

Abstract

This chapter deals with the determining of the time frame of possible transit navigation on the NSR. It includes also date of beginning and date of closing of transit ice-free zone (corridor) linking ports in the Europe with the ports of the Far East. The process of ice disintegration in individual seas leads to formation of ice-free zones allowing navigation of vessels that do not have ice reinforcements. It is assumed that those ice-free water zones are important, which open to general direction of connection with next sea and ultimately enable passage through all subsequent seas of the NSR. The results of studies of statistical data for the routes of vessels with very small draft (of 3.0–3.5 m) and vessels with a larger draft of depth restrictions of 14.5 m were presented. The PANAMAX-type vessels, commonly used in navigation, were accepted for further consideration. The average value, standard deviation, median and quartiles were presented. It is noticed that statistical results based on average value and standard deviation include discrete statistical data changes. It is assumed that they are inconvenient for the assessment of the situation and decision-making. For this reason, it was decided to approximate historical data from the eleven summer navigation seasons using the second-degree polynomial curves. The probability of existence of ice-free transit zone was applied on diagram for opening and closing ice-free transit zone (corridor) for western and eastern parts of the NSR. The probability of the transit zone free from ice in western part of the NSR does not exceed 89%. It shows, when planning vessel voyage schedule based on historical data, there is no 100% certainty that there will be ice-free conditions in western part of the NSR. The highest probability of an ice-free zone in western part of the NSR falls on Julian day 268. For the eastern part of the NSR (Chukchi and East Siberian seas), probability of existence to the given day ice-free transit zone is limited by opening curve of the transit zone in the eastern part of the NSR and curve of closing this zone to the given day of the year. Probability of existence ice-free transit zone in eastern part is 100%. Based on historical data, it can be expected that there were ice-free conditions in days from 258 to 271 with probability of 100% on eastern part of the NSR. The highest probability of existence ice-free zone along the whole NSR route and thus the most convenient conditions for successful completion of transit voyage is during 16 days from 258 to 271 Julian days. By means of polynomial function graphs for historical data, it can continuously determine probability of existence of transit zone for ice-free navigation in the western and eastern part of the NSR for any day of the year. The diagram can be used to plan beginning and completing dates of vessel’s voyage through the NSR, taking into account probability of existence of ice-free zone in selected area.