Search

Internal solitary waves (ISWs) propagating in a stably stratified two‐layer fluid in which the upper boundary condition changes from open water to ice are studied for grease, level, and nilas ice. The ISW‐induced current at the surface is capable of transporting the ice in the horizontal direction. In the level ice case, the transport speed of, relatively long ice floes, nondimensionalized by the wave speed is linearly dependent on the length of the ice floe nondimensionalized by the wave length. Measures of turbulent kinetic energy dissipation under the ice are comparable to those at the wave density interface. Moreover, in cases where the ice floe protrudes into the pycnocline, interaction with the ice edge can cause the ISW to break or even be destroyed by the process. The results suggest that interaction between ISWs and sea ice may be an important mechanism for dissipation of ISW energy in the Arctic Ocean. Key Points: Internal solitary waves in partially ice‐covered water are generated in the laboratoryInternal solitary wave‐induced currents can transport the ice horizontallyIn the laboratory, dissipation of turbulent kinetic energy under the ice is comparable to that at the wave density interface [ABSTRACT FROM AUTHOR]

When modeling gravity wave propagation through an array of discrete ice floes, considered as a homogenous elastic continuum, the equivalent elasticity is less than the intrinsic material elasticity of ice. The array behaves increasingly like a collection of rigid floating masses when the floe sizes decrease. Extending a former wave flume experiment with polyethylene plates (Sakai & Hanai, 2002, https://web2.clarkson.edu/projects/iahrice/IAHR%202002/Volume%202/189.pdf), we conducted an experiment with saline ice floes at the Hamburg Ship Model Basin (HSVA). Using the measured wave number and the dispersion relation from a continuous elastic plate theory, we determine the equivalent elasticity. Parallel theoretical solutions are obtained using the matched eigenfunction expansion method (Kohout et al., 2007, https://doi.org/10.1016/j.jfluidstructs.2006.10.012), assuming ice floes as an array of thin elastic plates floating over inviscid water. Despite data scatter in laboratory tests, the celerity (phase speed) from the laboratory and theoretical results both show a decreasing trend when the floe size reduces. The corresponding equivalent elastic modulus decreases from the intrinsic modulus to zero. The matched eigenfunction expansion method is then applied to investigate cases under field conditions. Using all the theoretical results, an empirical relation is proposed for the equivalent elasticity in terms of wavelength, floe size, and length scale from the intrinsic elasticity of the floes. In addition to celerity, wave amplitude along the ice cover is compared with the theoretical results. Large discrepancies of wave attenuation from laboratory and theoretical solutions are found, indicating that attenuation mechanisms other than wave scattering need to be considered. Plain Language Summary: Ocean wave forecasts in the ice‐covered seas require reliable modeling of ice effect on wave propagation. The wave dispersion and damping rate due to the ice cover are different from the propagation in open water. One way is to consider the total effect of a field of fragmented ice floes as one continuous elastic sheet. However, the elasticity of the sheet is not measurable directly, which could be much lower than the intrinsic elasticity of ice. In this study, we examine a single‐period wave propagating through an array of ice floes using both physical measurement and a theoretical approach. We analyze data from two laboratory experiments and the parallel theoretical studies. The theoretical studies are also extended into field scales using parameters collected from two field experiments. By assimilating all results, we determine the dependence of the equivalent elasticity of the sheet on the floe size. Furthermore, the surface undulation due to free edges makes the attenuation measurement challenging. Despite this difficulty, extra damping beyond wave scattering is observed. Key Points: Wave celerity (phase speed) and amplitude over an array of ice floes are obtained from laboratory tests and theoretical solutionsBoth show celerity decreases as floe size decreases, while decay of amplitudes in laboratory data is generally higherAn empirical formula for the equivalent elasticity of an array of floes is derived from wave numbers obtained in the theoretical results [ABSTRACT FROM AUTHOR]

This paper presents the analysis of floe-size distribution (FSD) data obtained in laboratory experiments of ice breaking by waves. The experiments, performed at the Large Ice Model Basin (LIMB) of the Hamburg Ship Model Basin (Hamburgische Schiffbau-Versuchsanstalt, HSVA), consisted of a number of tests in which an initially continuous, uniform ice sheet was broken by regular waves with prescribed characteristics. The floes' characteristics (surface area; minor and major axis, and orientation of equivalent ellipse) were obtained from digital images of the ice sheets after five tests. The analysis shows that although the floe sizes cover a wide range of values (up to 5 orders of magnitude in the case of floe surface area), their probability density functions (PDFs) do not have heavy tails, but exhibit a clear cutoff at large floe sizes. Moreover, the PDFs have a maximum that can be attributed to wave-induced flexural strain, producing preferred floe sizes. It is demonstrated that the observed FSD data can be described by theoretical PDFs expressed as a weighted sum of two components, a tapered power law and a Gaussian, reflecting multiple fracture mechanisms contributing to the FSD as it evolves in time. The results are discussed in the context of theoretical and numerical research on fragmentation of sea ice and other brittle materials. [ABSTRACT FROM AUTHOR]

Renewed political and commercial interest in the resources of the Arctic, the reduction in the extent and thickness of sea ice, and the recent failings that led to the Deepwater Horizon oil spill, have prompted industry and its regulatory agencies, governments, local communities and NGOs to look at all aspects of Arctic oil spill countermeasures with fresh eyes. This paper provides an overview of present oil spill response capabilities and technologies for ice-covered waters, as well as under potential future conditions driven by a changing climate. Though not an exhaustive review, we provide the key research results for oil spill response from knowledge accumulated over many decades, including significant review papers that have been prepared as well as results from recent laboratory tests, field programmes and modelling work. The three main areas covered by the review are as follows: oil weathering and modelling; oil detection and monitoring; and oil spill response techniques. [ABSTRACT FROM AUTHOR]

An experimental investigation of flexural-gravity waves was performed in the Hamburg Ship Model Basin HSVA ice tank. Physical characteristics of the water-ice system were measured in several locations of the tank with a few sensors deployed in the water and on the ice during the tests. The three-dimensional motion of ice was measured with the optical system Qualisys; water pressure was measured by several pressure sensors mounted on the tank wall, in-plane deformations of the ice and the temperatures of the ice and water were measured by fiber optic sensors; and acoustic emissions were recorded with compressional crystal sensors. The experimental setup and selected results of the tests are discussed in this paper. Viscous-elastic model (Burgers material) is adopted to describe the dispersion and attenuation of waves propagating below the ice. The elastic modulus and the coefficient of viscosity are calculated using the experimental data. The results of the measurements demonstrated the dependence of wave characteristics from the variability of ice properties during the experiment caused by the brine drainage. We showed that the cyclic motion of the ice along the tank, imitating ice drift, and the generation of under ice turbulence cause an increase of wave damping. Recorded acoustic emissions demonstrated cyclic microcracking occurring with wave frequencies and accompanying bending deformations of the ice. This explains the viscous and anelastic rheology of the model ice. [ABSTRACT FROM AUTHOR]