Size distribution and shape properties of relatively small sea-ice floes in the Antarctic marginal ice zone in late winter

Toyota, Takenobu; Haas, Christian; Tamura, Takeshi

doi:10.1016/j.dsr2.2010.10.034

Cited by 117 publications

(240 citation statements)

References 34 publications

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“…p(D|D max > 200 m) = δ(D − 200 m). This latter assumption is somewhat vestigial but was related to the fact that wavelengths that break in the ice are usually less than about 400 m. The rest of our approximation is similar to the FSD used by Dumont et al (2011), which was based on the renormalisation group (RG) approach to the same problem, used by Toyota et al (2011). However, this formula made the mean floe size a discontinuous function of the maximum floe size, so we have modified it to a continuous (as opposed to discrete) FSD -a power-law-type probability density function p(D) truncated at D = D max , but with the same exponent as before:…”

Section: Floe-size Distributionmentioning

confidence: 87%

“…where γ = 2+log f/ log ξ , f is the fragility in the RG formulation of Toyota et al (2011), and ξ 2 is the number of pieces formed during each successive break-up in the same RG formulation. We use D min = 20 m, f = 0.9 and ξ = 2, making γ ≈ 1.84.…”

Section: Floe-size Distributionmentioning

confidence: 99%

“…Toyota et al, 2011;Herman, 2010). This can influence both the dynamics and thermodynamics of the ice, ocean and atmosphere in the MIZ.…”

Section: Introductionmentioning

confidence: 99%

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Wave–ice interactions in the neXtSIM sea-ice model

2017

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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.

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Section: Floe-size Distributionmentioning

confidence: 87%

Section: Floe-size Distributionmentioning

confidence: 99%

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Wave–ice interactions in the neXtSIM sea-ice model

2017

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“…However, these facts do not affect the general conclusions formulated above. The present results agree with the findings of Squire et al (1995), described in the introduction, and provide another evidence -obtained with a very different model than that of Squire and colleagues -in favor of the hypothesis that it is the ice itself (its thickness and strength) and not the incident waves that decide upon the dominating floe size in MIZ, at least during the initial stages of ice breaking (at later stages, many other factors lead to further fragmentation of ice floes, producing wide, heavy-tailed FSDs typically observed in inner parts of MIZ; see, e.g., Toyota et al, 2011Toyota et al, , 2016, and references there). In particular, it is worth stressing that in terms of the floe size resulting from breaking, the results are not sensitive to the modeled attenuation rates of wave energy (which, as already mentioned in Sect.…”

Section: Discussionmentioning

confidence: 99%

Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave–ice model

Herman

2017

The Cryosphere

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Abstract. In this paper, a coupled sea ice-wave model is developed and used to analyze wave-induced stress and breaking in sea ice for a range of wave and ice conditions. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid "grains" floating on the water surface that can be connected to their neighbors by elastic joints. The joints may break if instantaneous stresses acting on them exceed their strength. The wave module is based on an open-source version of the Non-Hydrostatic WAVE model (NHWAVE). The two modules are coupled with proper boundary conditions for pressure and velocity, exchanged at every wave model time step. In the present version, the model operates in two dimensions (one vertical and one horizontal) and is suitable for simulating compact ice in which heave and pitch motion dominates over surge. In a series of simulations with varying sea ice properties and incoming wavelength it is shown that wave-induced stress reaches maximum values at a certain distance from the ice edge. The value of maximum stress depends on both ice properties and characteristics of incoming waves, but, crucially for ice breaking, the location at which the maximum occurs does not change with the incoming wavelength. Consequently, both regular and random (Jonswap spectrum) waves break the ice into floes with almost identical sizes. The width of the zone of broken ice depends on ice strength and wave attenuation rates in the ice.

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“…The exponent α has been commonly estimated by fitting a straight line on a log-log plot (for either FND or CFND) using least-square fit (LSF) (e.g., Rothrock and Thorndike, 1984;Toyota et al, 2011 and2006;Wang et al, 2016;Stern et al, 2017a and2017b). A recent study by Clauset et al (2009) and Virkar and Clauset (2014) suggested a method to calculate the exponent α for any given dataset by using the maximum likelihood estimator.…”

Section: Research Articlementioning

confidence: 99%

Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

Hwang

Wilkinson

Maksym

et al. 2017

Elementa: Science of the Anthropocene

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ǁǁBreakup of the near-continuous winter sea ice into discrete summer ice floes is an important transition that dictates the evolution and fate of the marginal ice zone (MIZ) of the Arctic Ocean. During the winter of 2014, more than 50 autonomous drifting buoys were deployed in four separate clusters on the sea ice in the Beaufort Sea, as part of the Office of Naval Research MIZ program. These systems measured the ocean-ice-atmosphere properties at their location whilst the sea ice parameters in the surrounding area of these buoy clusters were continuously monitored by satellite TerraSAR-X Synthetic Aperture Radar. This approach provided a unique Lagrangian view of the winter-to-summer transition of sea ice breakup and floe size distribution at each cluster between March and August. The results show the critical timings of a) temporary breakup of winter sea ice coinciding with strong wind events and b) spring breakup (during surface melt, melt ponding and drainage) leading to distinctive summer ice floes. Importantly our results suggest that summer sea ice floe distribution is potentially affected by the state of winter sea ice, including the composition and fracturing (caused by deformation events) of winter sea ice, and that substantial mid-summer breakup of sea ice floes is likely linked to the timing of thermodynamic melt of sea ice in the area. As the rate of deformation and thermodynamic melt of sea ice has been increasing in the MIZ in the Beaufort Sea, our results suggest that these elevated factors would promote faster and more enhanced breakup of sea ice, leading to a higher melt rate of sea ice and thus a more rapid advance of the summer MIZ.

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Size distribution and shape properties of relatively small sea-ice floes in the Antarctic marginal ice zone in late winter

Cited by 117 publications

References 34 publications

Wave–ice interactions in the neXtSIM sea-ice model

Wave–ice interactions in the neXtSIM sea-ice model

Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave–ice model

Winter-to-summer transition of Arctic sea ice breakup and floe size distribution in the Beaufort Sea

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