Author(s): Guillaume Boutin; Timothy Williams; Pierre Rampal; Einar Olason; Camille Lique
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Abstract: The recent decrease in Arctic sea ice extent leaves more open water available for the generation of surface ocean waves. When they propagate in sea ice, these waves are attenuated, limiting the wave-ice interactions to the area at the interface between the pack ice and the open ocean, commonly referred to as the marginal ice zone (MIZ). In this region, waves can bend and break the ice floes, thus fragmenting sea ice. The consequences of this fragmentation on sea ice dynamics are poorly known, although it has often been suggested that fragmented sea ice is likely to have its resistance to deformation reduced. Here, we investigate the potential impact of wave-induced sea ice fragmentation on sea ice dynamics using a new coupled framework between a spectral wave model and the sea ice model neXtSIM, which includes a MaxwellElasto Brittle rheology. Using a case study in the Barents Sea, we find that fragmented sea ice, for which the internal stress is reduced, is significantly more mobile than when it is unbroken. This increase in mobility is particularly visible for high sea ice concentrations. We describe two effects of fragmentation on sea ice dynamics: it maintains high velocities when the wind speed of a storm starts decreasing, and it allows for sea ice to be mobile even in very calm conditions. This modulation of sea ice mobility by waves has important implications for both sea ice forecast applications and longer-term simulations.
Year: 2020