The attenuation rates of ocean waves in the marginal ice zone

Wadhams, Peter; Squire, Vernon A.; Goodman, D. J.; Cowan, Andrew M.; Moore, Stuart C.

doi:10.1029/jc093ic06p06799

Cited by 268 publications

(316 citation statements)

References 12 publications

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“…Values of the attenuation coefficient seen are up to 2 orders of magnitude greater than previous measurements in the "broken floe MIZ," in both Arctic and Antarctic, as reported in Wadhams et al [1988] and Kohout et al [2014]. This is perhaps counterintuitive, given the greater ice thicknesses (up to 4.0 m) present in those more "classic" MIZs, though the dominant energy dissipation mechanism there-currently presumed to be scattering-is of a completely different nature to the viscous eddy dissipation which takes place in the pancake fields.…”

Section: Discussioncontrasting

confidence: 56%

“…There is very little energy above 14 s, thus attenuation cannot be represented by these data. Below 7 s, we see the classic "rollover" in attenuation, seen in all previous measurements [Wadhams et al, 1988]. We attribute this to the fact that energy at such short periods from the open ocean has already been attenuated before it reaches the outermost buoy.…”

Section: 1002/2015gl063628supporting

confidence: 58%

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Relating wave attenuation to pancake ice thickness, using field measurements and model results

Doble

Carolis

Meylan

et al. 2015

Geophysical Research Letters

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117

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Wave attenuation coefficients (α, m−1) were calculated from in situ data transmitted by custom wave buoys deployed into the advancing pancake ice region of the Weddell Sea. Data cover a 12 day period as the buoy array was first compressed and then dilated under the influence of a passing low‐pressure system. Attenuation was found to vary over more than 2 orders of magnitude and to be far higher than that observed in broken‐floe marginal ice zones. A clear linear relation between α and ice thickness was demonstrated, using ice thickness from a novel dynamic/thermodynamic model. A simple expression for α in terms of wave period and ice thickness was derived, for application in research and operational models. The variation of α was further investigated with a two‐layer viscous model, and a linear relation was found between eddy viscosity in the sub‐ice boundary layer and ice thickness.

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Section: Discussioncontrasting

confidence: 56%

Section: 1002/2015gl063628supporting

confidence: 58%

Relating wave attenuation to pancake ice thickness, using field measurements and model results

Doble

Carolis

Meylan

et al. 2015

Geophysical Research Letters

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117

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“…Simultaneous measurements of wave period, attenuation rate, and wavelength are required to perform the calibration, which has never been achieved and may not be feasible with contemporary measurement techniques. In situ measurements typically use multiple wave buoys to extract attenuation rate and wave period [see e.g., Wadhams et al, 1988;Meylan et al, 2014], while attenuation rate and wavelength can be recovered using remote sensing observations, e.g., synthetic aperture radar (SAR) imagery [Liu et al, 1992]. The relationship between wave period and wavelength in ice-covered oceans (i.e., the dispersion relation) is not known, however.…”

Section: 1002/2015jc010881mentioning

confidence: 99%

“…Therefore, we rely on experimental measurements of wave energy attenuation coefficients against wave period. A synthesis of five experimental data sets collected in the Bering Sea and Greenland Sea between 1978 and 1983 was conducted by Wadhams et al [1988]. However, we will use a more recent data set in which five contemporary wave sensors were deployed in the Antarctic marginal ice zone to measure wave energy attenuation and wave period [Kohout and Williams, 2013;Kohout et al, 2015].…”

Section: Model Calibration With Experimental Datamentioning

confidence: 99%

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

2015

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Continuum‐based models that describe the propagation of ocean waves in ice‐infested seas are considered, where the surface ocean layer (including ice floes, brash ice, etc.) is modeled by a homogeneous viscoelastic material which causes waves to attenuate as they travel through the medium. Three ice layer models are compared, namely a viscoelastic fluid layer model currently being trialed in the spectral wave model WAVEWATCH III® and two simpler viscoelastic thin beam models. All three models are two dimensional. A comparative analysis shows that one of the beam models provides similar predictions for wave attenuation and wavelength to the viscoelastic fluid model. The three models are calibrated using wave attenuation data recently collected in the Antarctic marginal ice zone as an example. Although agreement with the data is obtained with all three models, several important issues related to the viscoelastic fluid model are identified that raise questions about its suitability to characterize wave attenuation in ice‐covered seas. Viscoelastic beam models appear to provide a more robust parameterization of the phenomenon being modeled, but still remain questionable as a valid characterization of wave‐ice interactions generally.

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“…When ocean waves penetrate an ice cover, the wave energy is significantly attenuated by sea ice particularly for shorter wave periods, and in turn sea ice is fractured by the flexural force from penetrating waves (Squire and Moore, 1980;Wadhams et al, 1988;Squire et al, 1995).…”

Section: Introductionmentioning

confidence: 99%

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

Toyota

Haas

Tamura

2011

Deep Sea Research Part II: Topical Studies in Oceanography

119

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In the marginal sea ice zone (MIZ), where relatively small ice floes are dominant, the floe size distribution is an important parameter affecting melt processes given the larger cumulative perimeter of multiple small floes compared with a single ice floe of the same area. Smaller ice floes are therefore subject to increased lateral melt. However, the available data have been very limited so far. Analysis of sea ice in the Sea of Okhotsk revealed that while floe size distribution is basically scale invariant, a regime shift occurs at a size of about 40 m. In order to extend this preliminary result to the Antarctic MIZ and further examine the controlling factors, the first concurrent ice floe size and ice thickness measurements were conducted in the northwestern Weddell Sea and off Wilkes Land (around 64°S, 117ºE) with a heli-borne digital video camera in the late winter of 2006 and 2007, respectively. The floe sizes ranged from 2 to 100 m. Our analysis shows: 1) the scale invariance and regime shift are confirmed in both regions; 2) the floe size at which regime shift occurs slightly increases from 20 to 40 m, with ice thickness, consistent with the theory of the flexural failure of sea ice; and 3) the aspect ratio is 1.6-1.9 on average, close to the previous results. Based on these results, the processes affecting the floe size distribution and the subsequent implications on melt processes are discussed.By applying a renormalization group method to interpret the scale invariance in floe size distribution, the fractal dimension is related to the fragility of sea ice. These results indicate the importance of wave-ice interaction in determining the floe size distribution.

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The attenuation rates of ocean waves in the marginal ice zone

Cited by 268 publications

References 12 publications

Relating wave attenuation to pancake ice thickness, using field measurements and model results

Relating wave attenuation to pancake ice thickness, using field measurements and model results

Comparison of viscoelastic‐type models for ocean wave attenuation in ice‐covered seas

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

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