Abstract

Due to the interaction with land or other (larger) ice masses, high internal stress can occur inside sea ice. During the MOSAiC Expedition the level ice pressure in the vicinity of the research vessel Polarstern was measured over a time period of six months by three pressure panels frozen into the ice. The objective is to investigate the relationship of changing level ice conditions and the internal ice pressure in the vicinity of structures.

Introduction

In fall 2019 the biggest arctic expedition of all times – the MOSAiC Expedition1 led by the Alfred-Wegener-Institut2 started: Research vessel Polarstern (Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung, 2017) left Tromsø harbor to travel towards north, where it is frozen into the ice for about one year drifting across the Arctic along with the natural ice drift. Hence, this is a high-tech repetition of the famous Fram Expedition from 1893 to 1896 by Fridtjof Nansen. The expedition's objective is to record a vast variety of interdisciplinary data during an entire annual cycle, including the arctic winter. The obtained insights are supposed to provide a better understanding of the Arctic, especially with respect to climate change. Within the larger scientific scope of the expedition one sub-project was the measurement of long-term level ice pressure in the vicinity of a larger structure (i.e. the Polarstern) and a possible dependency of the vessel to changes of the level ice pressure and vice versa.

Detailed knowledge of ice pressures (or stresses) is of interest both from a scientific as well as an engineering point of view. Examples where these quantities play an important role are ice dynamics models (Hibler, 1979; Richter-Menge, 1997; Richter-Menge and Elder, 1998) or the formation of pressure ridges (Parmerter and Coon, 1972). The latter ones contribute to the motion of the ice by wind forces acting on the pressure ridge sails (Arya, 1973), while also forming natural obstacles even large ice-breaking ships cannot traverse (Kovacs et al., 1973)

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