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Dynamics of Arctic Leads

Tildelt: kr 89 999

It is well documented that the Arctic Ocean is in a transition from perennially ice-covered ocean to a seasonally ice-covered one (Meredith et al., 2019). The shrinking and thinning of the ice cover has been attributed to changes in atmospheric and oceanic forcing (Notz and Stroeve, 2016; Polyakov et al. 2017). However, increasing evidence shows that these trends are amplified by sea ice fracturing (Rampal et al., 2009; Itkin et al., 2017). One remarkable finding is that the thinning and warming of the pack ice has transformed it to have weaker in material strength and to be more vulnerable to the atmospheric forcing than before (Graham, et al. 2019). The project will begin with a detailed analysis of major fracturing events during the MOSAiC. Initial screening of the data indicates that we have captured ten events which can be detected both from ship radar and satellite data and are tens of kilometers long. As a first step, events will be related to external forcing (cyclones, tides, ocean swell). Then we will examine preconditions of these events. This includes analysis of waves on sea ice, ice quakes, distribution and magnitudes of sea ice stresses, ice thickness, snow/ice temperature as well as mm-scale strains of ice pack. All the necessary data have collected by the MOSAiC ice dynamics team and are readily available. Second step is to examine the hypothesis that the LKF’s are initiated as local fractures which have been connected together. For this, we will conduct two types of data analysis. Firstly, we will look for signatures of local, but not connected, fractures from the satellite images prior to the actual detection of the LKF. Secondly, we will also examine those fracturing events which have been detected locally at the MOSAiC Central Observatory, but not developed to LKF. Presumably, differences in those situations reveal underlying physics of evolution of LKF’s. Finally, ship radar data will used to quantify intensity of ridging in the MOSAiC floe.