Mechanisms of fast-ice development in the south-eastern Laptev Sea: a case study for winter of 2007/08 and 2009/10

Abstract

Accurate representation of fast ice in numerical models is important for realistic simulation of numerous sea-ice and ocean variables. In order to simulate seasonal and interannual variability of fast-ice extent, the mechanisms controlling fast-ice development need to be thoroughly understood. The objective of this paper is to investigate mechanisms contributing to the advance of fast-ice edge to its winter location in the south-eastern Laptev Sea. The study is based on time series of synthetic aperture radar (SAR) imagery for winter 2007/08 and 2009/10. A detailed examination of SAR-based ice drift showed that several grounded ice features are formed offshore prior to fast-ice expansion. These features play a key role in offshore advance of the fast-ice edge and serve as stabilizing points for surrounding pack ice as it becomes landfast. Electromagnetic ice thickness measurements suggest that the grounded ice ridges over water depths of ca. 20 m water might be responsible for interannual variations in fast-ice edge position. Contrary to previous studies, we conclude that grounding is a key mechanism of fast-ice development in the south-eastern Laptev Sea.