Types of sea ice conditions north of Spitzbergen archipelago

Abstract

Sea ice is an important part of the Arctic climate system. In the recent decade, rapid changes in the sea ice conditions have been observed: sea ice extent and sea ice thickness are declining; conversely, ice drift speed and deformations are increasing [1–10]. The main aim of this paper was to describe the variability of sea ice conditions north of the Svalbard archipelago and analyze the changes occurring there. For most of the year, a stable polynya is observed north of the archipelago, which is commonly called “Whalers Bay”. The prevailing wind direction (8–9 months out of 12) is north-east, thus, almost throughout the whole year, conditions persist that support the flow of warmer Atlantic waters (AW) to the surface. Stable upwelling, together with the observed increase in AW’s temperature, contributes to the formation of the quasi-stationary polynya “Whalers Bay”. The ice conditions north of the Spitsbergen archipelago are changing extremely dynamically. However, all their diversity can be grouped into four main types. Type 1 — the area to the north of the archipelago is covered with ice; type 2 — the ice edge moves to the north of the archipelago; 3 — “Whalers Bay” polynya; 4 — an intermediate type, when a “passage” is formed to the Barents Sea between the ice edge and the northern coast of the archipelago. This study showed that since the mid-1990s the frequency of type 1 has significantly decreased, conversely, type 3 has become predominant, and the frequency of occurrence of type 2 has also increased. The maximum area of the polynya was observed in February 2012 and 2014, when the ice edge reached 82,5°N and 50°E, and 83°N and 46°E respectively. The lightest ice conditions were observed in 2012, 2013 and 2016. The main periods of 2–3, 5–6 and 14 years were identified in open water area variability. The ice cover to the north of the archipelago is largely presented by the conditions similar to the marginal ice zone with an actively changing ice edge configuration and the combined influence of factors characteristic of open sea areas and ice-covered areas. It is here that intense heat exchange takes place between the ocean and the atmosphere. The heat fluxes directed from the ocean to the atmosphere in the area of the polynya have increased by about 4 TW over the past 40 years. The highest correlation between the heat flux and the area of open water is observed with a lag of 2 months.