This article was published on 12 September 2022.
👤 A. Toffoli, J. P. A. Pitt, A. Alberello and L. G. Bennetts
A summary is given on the utility of laboratory experiments for gaining understanding of wave attenuation in the marginal ice zone, as a complement to field observations, theory and numerical models. It is noted that most results to date are for regular incident waves, which, combined with the highly nonlinear wave–floe interaction phenomena observed and measured during experimental tests, implies that the attenuation of regular waves cannot necessarily be used to infer the attenuation of irregular waves. Two experiments are revisited in which irregular wave tests were conducted but not previously reported, one involving a single floe and the other a large number of floes, and the transmission coefficients for the irregular and regular wave tests are compared. The transmission spectra derived from the irregular wave tests agree with the regular wave data but are overpredicted by linear models due to nonlinear dissipative processes, regardless of floe configuration.
This article is part of the theme issue ‘Theory, modelling and observations of marginal ice zone dynamics: multidisciplinary perspectives and outlooks’.
Ocean waves are a defining component of the marginal ice zone (MIZ). They regulate floe sizes and ice dynamics in the MIZ, and hence ice extent and volume (see also the reviews in this issue). The ability to predict wave evolution in the MIZ, particularly wave attenuation over distance, is crucial to modelling wave-driven processes, such as ice break-up, and hence informing climate studies, evaluating ecosystem adaptation to climate change and planning the exploitation of natural resources in polar regions. Field campaigns are critical to understanding and modelling fundamental physics, but the harsh MIZ environment makes in situ observations challenging. As a complement or an alternative, laboratory experiments can be used to model complex ocean processes under controlled conditions, even in extreme sea states.
Laboratory experiments have a long tradition in the field of marine hydrodynamics, typically using model ice (saline or doped). They have only relatively recently started to be used to investigate wave–floe interactions and wave propagation in the MIZ, to evaluate wave attenuation (and closely related wave transmission) and concurrent wave forcing on floes, e.g. break-up and rafting. The majority of laboratory experiments on wave propagation in the MIZ employ artificial ice floes (e.g. plastic plates), as they are more versatile, e.g. do not require an ice tank and are easier to attach instruments to, while also providing a more compliant elastic response than does model ice, which exhibits unwanted plastic behaviour.
Full article can be retrieved here.