Relating arctic pack ice stress and deformation under winter conditions

[1] Together, thermodynamic and dynamic processes determine the thickness distribution of the ice cover on polar oceans, which governs the exchange of energy between the atmosphere and the ocean. Key to the dynamic processes is the mechanical behavior of the ice cover. During the Surface Heat Budget of the Arctic Ocean (SHEBA) field experiment, we deployed sensors to measure the internal ice stress at several locations within a 15 × 15 km area. These measurements are combined with satellite-derived ice motion and imagery products. The objective is to make a first step toward using these data sources for evaluating sea ice dynamics models by assessing whether the stress signal can be qualitatively linked to the regional-scale (10–100 km) deformation activity. Four case studies are presented, each with distinguishing characteristics: consolidation of the seasonal ice zone against the Alaskan coast (5–7 December 1997); advancement of the consolidation zone into the perennial ice pack (11–13 December); extreme divergence (14–17 January); and consolidation of the pack against Wrangel Island and the Siberian coast (20–23 February). The results of this analysis (1) demonstrate that stress measurements are related to the regional deformation behavior of the ice cover, (2) confirm that regional-scale ice dynamics is primarily a function of coastal geometry and sustained, large-scale wind direction and magnitude, (3) provide continued evidence that the ice pack behaves as a granular hardening plastic, and (4) encourage pursuit of efforts to use direct measurements of ice stress and deformation in the formulation and development of sea ice dynamics models.

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