The Russian Arctic seas ice age composition and thickness variation in winter periods at the beginning of the 21st century

Abstract

The purpose of the paper is to analyze the large-scale peculiarities of ice age composition and thickness in winter period (October–May) along the entire stripe of the Russian Arctic seas from the Novaya Zemlya Archipelago to Alaska, as well as to assess the multi-year changes taking place in early 21st century. The source of the information used for the present paper is the electronic ice charts at the end of every month, developed in the AARI from 1997 to 2018.On the average, during the period 1997–2018, from month to month, the consecutive and ordered changes of ice area of given age take place in accordance with the general ice thickness increase. In October–December the grey-white and first year thin ice (15–70 cm) prevails in the Arctic seas, in January–February — the first-year medium ice (70–120 cm), in March–May — the first-year thick ice (more than 120 cm).The period from 1997 to 2018 consists of two parts (1997–2003 and 2004–2018) principally differing from one another by the peculiarities of ice age composition. The basic content of the changes in the 21st century is the decrease of relatively thicker ice area and increase of that of relatively thinner ice.On the average, in the winter periods of 2004–2018, (1) the area of ice thinner than 70 cm (nilas, grey, grey-white and first year thin) became 12 % less than in 1997–2003, and (2) the area of ice thicker than 70 cm (first year medium, first year thick, second year and multi-year) became 18 % larger than in 1997–2003. The most significant changes regard to the second year and multi-year ice, their area in winter period decreased about 10 times. Decrease of the rate of first year ice growth is accompanied with delay of the dates when the first year ice reaches the values of 70 and 120 cm.Correspondingly, the weighted mean ice thickness also changes. On the average, in 2004–2018 ice thickness has got about 40 cm less than in 1997–2003; by the end of cold period (May), ice thickness decrease from 153 to 117 cm.The typical feature of the observed changes is an abrupt transformation from one climatic state of ice cover to another during only one hydrological year.