Abstract
Abstract. In this paper we describe a waves-in-ice model (WIM), which calculates ice breakage and the wave radiation stress (WRS). This WIM is then coupled to the new sea-ice model neXtSIM, which is based on the elasto-brittle (EB) rheology. We highlight some numerical issues involved in the coupling and investigate the impact of the WRS, and of modifying the EB rheology to lower the stiffness of the ice in the area where the ice has broken up (the marginal ice zone or MIZ). In experiments in the absence of wind, we find that wind waves can produce noticeable movement of the ice edge in loose ice (concentration around 70 %) – up to 36 km, depending on the material parameters of the ice that are used and the dynamical model used for the broken ice. The ice edge position is unaffected by the WRS if the initial concentration is higher (≳ 0.9). Swell waves (monochromatic waves with low frequency) do not affect the ice edge location (even for loose ice), as they are attenuated much less than the higher-frequency components of a wind wave spectrum, and so consequently produce a much lower WRS (by about an order of magnitude at least).In the presence of wind, we find that the wind stress dominates the WRS, which, while large near the ice edge, decays exponentially away from it. This is in contrast to the wind stress, which is applied over a much larger ice area. In this case (when wind is present) the dynamical model for the MIZ has more impact than the WRS, although that effect too is relatively modest. When the stiffness in the MIZ is lowered due to ice breakage, we find that on-ice winds produce more compression in the MIZ than in the pack, while off-ice winds can cause the MIZ to be separated from the pack ice.
Highlights
Wave–ice interactions have received a great deal of attention in recent years (e.g. Dumont et al, 2011; Kohout et al, 2014; Ardhuin et al, 2016, 2017), with progress in both modelling and measuring waves in ice
As well as being dangerous for shipping in themselves, large waves increase the amount of ice breakage in the marginal ice zone (MIZ), creating an extra hazard as small floes could potentially be thrown onto a ship deck, for example
We have investigated the impact of the wave radiation stress (WRS) on sea-ice state and drift in an idealised domain
Summary
Wave–ice interactions have received a great deal of attention in recent years (e.g. Dumont et al, 2011; Kohout et al, 2014; Ardhuin et al, 2016, 2017), with progress in both modelling and measuring ( via synthetic aperture radar imagery or SAR) waves in ice. Et al.: Wave–ice interactions in neXtSIM warm water to travel under the ice floes and enhance the melting from the edges. This was true even for large floes ( ∼ 1 km), when the lateral-to-horizontal surface-area ratio is quite small. When one cell is highly damaged, the likelihood of the surrounding cells becoming damaged is increased, leading to the rapid (i.e. after a few sea-ice-model time steps) emergence of very localised lines of damaged cells where sea ice can deform almost freely These lines of concentrated damage can accommodate large deformation (i.e. opening, ridging and shearing) in a way that is similar to the so-called linear kinematic features that are observed from satellites (Kwok, 2001). Its response to the Young’s modulus was previously uninvestigated
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