Spatial heterogeneity in the structure of fast ice level in the area of the research station “Ice base Cape of Baranov”

Abstract

Two ice coring transects in the Shokalsky Strait were made in order to analyze a spatialheterogeneity in the structure of fast ice in the area of the research station “Ice base Cape of Baranov”. The first transect was 16 km long made off the shore of Bolshevik Island in a western direction across the Shokalsky Strait. The second transect was made along the eastern shore of the Shokalsky Strait. Structural analysis of the recovered sea ice cores shows that fast ice in the Shokalsky Strait features a complicated multilayer structure formed of congelation ice, congelation-frazil ice, frazil slush, and infiltration formations. Various conditions of ice formation form the ices of various genetic types. In terms of ice thickness, a sequence of layer occurrence and type, all level fast ice of the Shokalsky Strait in the area of the station can be divided into three main groups. The group I, being the most common one, is the ice group formed directly in the strait, approximately outside the 100 m isobath. Its structure comprises three to four layers. The average ice thickness measured in the end of May was 132 cm. A distinctive feature of the ice belonging to (or associated with) this group is the presence of a distinct lamination in the texture pattern for almost all recovered ice cores. The ice of this group also has an increased salinity compared to the ice of other groups, especially in the upper layers.

The ice of the group II prevails, mainly in closed bays or gulfs. This group ice forms in dynamically stable conditions. Formation of fast ice in these regions of the study area began some earlier than in other locations, and the thickness of this ice reached 160 cm or more.

The ice of the group III is transitional from the group II to the group I. Its distinctive feature is the presence of a thick layer of rafting ice. The main place of its formation is the boundary of separation of fast ice with drifting ice or open water.

In the Shokalsky Strait, in the bays and in the coastal regions, there was observed the spatial ordering of the columnar ice crystals. This feature was especially pronounced in level fast ice from the open part of the strait.