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

Abstract

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.

Dissipation of wind waves by pancake and frazil ice in the autumn Beaufort Sea

“…With m 2 /s and as used here, the impact would have been minor if included; for example, with an ice thickness of 40 cm (a relatively high value for this hindcast) and considering waves at 0.35 Hz (one of the more strongly affected wave frequencies measurable by buoy), the ice changes the group velocity by less than 1% of the open water group velocity, according to the Wang and Shen [] model. However, such behavior is not universal among viscoelastic models [ Mosig et al ., ].…”

Attenuation and directional spreading of ocean wave spectra in the marginal ice zone

“…Estimating their effects on wave energy attenuation is a difficult task, as most are non-linear processes. Although simplified empirical parameterizations have been developed to model the MIZ as a homogeneous linearly viscoelastic layer (Wang & Shen 2010), their validity is unresolved and calibration presents a major challenge that requires more data than are currently available (Mosig et al 2015). In contrast, wave scattering is conservative and redistributes the wave energy over the directional domain.…”

Sensitivity analysis of a viscoelastic parameterization for gravity wave dispersion in ice covered seas

“…However, the complexity of the mathematical structure in VEWS as discussed in Shen (2010, 2011) has invoked further study about the physical meaning of its multiple modes. Some discussions have appeared in Wang and Shen (2011) where the amplitude of horizontal/vertical motions at the free surface and the water/viscoelastic material interface were compared, and in Mosig et al (2015) where the phases of the modes at the free surface and interface was mentioned. In this study as well as in all our previous studies relating to this model, we have consistently chosen the mode closest to the open water case as the dominant mode, the same as what was done in studying wave propagation over a mud-layer (Dalrymple and Liu, 1978).…”

“…While the present paper was under review, one of the reviewers pointed out a recent paper by Mosig et al (2015). In which they compared VEWS and VESA, in addition to another viscoelastic model presented by Robinson and Palmer (1990).…”