Modelling the reorientation of sea-ice faults as the wind changes direction

• Main Authors: Wilchinsky, A. V., Feltham, D. L., Hopkins, M. A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: International Glaciological Society 2011
• Subjects: Annals of Glaciology; ice pack; Sea ice
• Online Access: https://centaur.reading.ac.uk/34582/; https://centaur.reading.ac.uk/34582/1/Wilchinsky_etal_2011b.pdf

A discrete-element model of sea ice is used to study how a 90° change in wind direction alters the pattern of faults generated through mechanical failure of the ice. The sea-ice domain is 400km in size and consists of polygonal floes obtained through a Voronoi tessellation. Initially the floes are frozen together through viscous–elastic joints that can break under sufficient compressive, tensile and shear deformation. A constant wind-stress gradient is applied until the initially frozen ice pack is broken into roughly diamond-shaped aggregates, with crack angles determined by wing-crack formation. Then partial refreezing of the cracks delineating the aggregates is modelled through reduction of their length by a particular fraction, the ice pack deformation is neglected and the wind stress is rotated by 90°. New cracks form, delineating aggregates with a different orientation. Our results show the new crack orientation depends on the refrozen fraction of the initial faults: as this fraction increases, the new cracks gradually rotate to the new wind direction, reaching 90° for fully refrozen faults. Such reorientation is determined by a competition between new cracks forming at a preferential angle determined by the wing-crack theory and at old cracks oriented at a less favourable angle but having higher stresses due to shorter contacts across the joints