Modelling attenuation of irregular wave fields by artificial ice floes in the laboratory

Abstract

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’.

Floes, the marginal ice zone and coupled wave-sea-ice feedbacks

“…(3) Sea ice becomes more susceptible to change, for example by (a) melting more rapidly [25,32,71], (b) consolidating more effectively [27,77], (c) being more mobile [78][79][80][81], (d) altering the attenuation and transmission of wave energy [22][23][24], (4) The sea ice cover changes, triggering local coupled feedbacks, and:…”

“…Sea ice is, at all scales, a floe composite, but in the MIZ these floes span a scale range from centimetres to kilometres and directly influence sea ice evolution and ice-ocean-atmospheric coupling. Fields of energetic waves bend sea ice, fracturing it into smaller pieces and leaving a field of small floes that alters sea ice properties as well as the transmission and scattering of wave energy [9,[21][22][23][24]. These smaller floes are then more prone to melting [25].…”

Wave-in-ice: theoretical bases and field observations

“…Field observations of the turbulent boundary layer such as [78] need to continue under different ice covers. More accessible laboratory experiment [84] (in this issue) can accelerate the understanding. Continued development of wave-in-ice theories will no doubt increase our knowledge in each of the identified processes, and perhaps discover more. With each step of the progress, comparisons with field data from in situ measurements and remote sensing is necessary.…”

“…Field observations of the turbulent boundary layer such as [78] need to continue under different ice covers. More accessible laboratory experiment [84] (in this issue) can accelerate the understanding.…”

A prognosticative synopsis of contemporary marginal ice zone research

“…The value of SAR measurements from space has already been well demonstrated in [37], while laboratory experiments using artificial, i.e. plastic, ice floes such as those described by Toffoli et al [38] provide a valuable perspective on the subtleties of how waves and floating bodies interact that can be extrapolated to Nature, e.g. nonlinear behaviour such as overwashing and the ramifications of irregular waves.…”