Seasonal and interannual changes of ice massifs in East Siberian sea

Abstract

The paper considers the seasonal and interannual variability of the Novosibirsky and Ayonsky ice massifs of the East Siberian Sea, which represent the main difficulty for navigation during summer. Analysis of ice conditions showed the tendency towards the onset of a new climatic period - “relative warming”. This is consistent with the regional quasi-periodic 30-year alternations beetween the “relatively cold” and “relatively warm” climatic periods identified in the AARI. We have compared ice conditions of the “relatively cold” period of 1958–1987 and the “relatively warm” period of 1988–2017. Since the end of the 1980s the ice massifs began to decrease more intensively with the onset of break up some 10–20 days earlier. In general, the drift ice area during summer has decreased by 15–20 % in the western part of the sea and by 20–30 % in eastern one. The fast decrease of close floatingice in the East Siberian Sea observed in the last decades resulted in increase of the possibilities of autonomous navigation. The latest works containing the analysis of in conditions of the East Siberian Sea belong to the 90s of last century. In these works ice conditions of the period of the 40–80s of the 20th century were considered. During this period, the background of the ice cover extent was high. As a result, the usage of the average values of ice massifs areas calculated on all observations series (since 1946), is not informative for characterizing ice conditions during separately taken periods.