Wave dispersion and dissipation in landfast ice: comparison of observations against models
- 1Department of Infrastructure Engineering, University of Melbourne, Parkville, Australia
- 2Physical Oceanography Laboratory, Ocean University of China, Qingdao, China
- 3The University Centre in Svalbard, Longyearbyen, Norway
- 4Norwegian Meteorological Institute, Oslo, Norway
- 5Department of Mathematics, University of Oslo, Oslo, Norway
- 6Arctic and Antarctic Research Institute (AARI), St. Petersburg, Russian Federation
- 7Australian Antarctic Division and Australian Antarctic Program Partnership, University of Tasmania, Hobart, Australia
- 8Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa, Chiba, Japan
- 9Laboratory for Regional Oceanography and Numerical Modeling, National Laboratory for Marine Science and Technology, Qingdao, China
Abstract. Observations of wave dissipation and dispersion in sea ice are a necessity for the development and validation of wave-ice interaction models. As the composition of the ice layer can be extremely complex, most models treat the ice layer as a continuum with effective, rather than independently measurable, properties. While this provides opportunities to fit the model to observations, it also obscures our understanding of the wave-ice interactive processes, particularly, it hinders our ability to identify under which environmental conditions these processes are of significance. Here, we aimed to reduce the number of free variables available by studying wave dissipation in landfast ice. That is, in continuous sea ice, such as landfast ice, the effective properties of the continuum ice layer should revert to the material properties of the ice. We present observations of wave dispersion and dissipation from a field experiment on landfast ice in the Arctic and Antarctic. Independent laboratory measurements were performed on sea ice cores from a neighbouring fjord in the Arctic to estimate the ice viscosity. Results show that the dispersion of waves in landfast ice is well described by theory of a thin elastic plate and such observations could provide an estimate of the elastic modulus of the ice. Observations of wave dissipation in landfast ice are about an order of magnitude larger than in ice floes and broken ice. Comparison of our observations against models suggests that wave dissipation is attributed to the viscous dissipation within the ice layer for short waves only, whereas turbulence generated through the interactions between the ice and waves is the most likely process for the dissipation of wave energy for long periods. The separation between short and long waves in this context is expected to be determined by the ice thickness through its influence on the lengthening of short waves. Further studies are required to measure turbulence underneath the ice independently of observations of wave attenuation to confirm our interpretation of the results.
Joey J. Voermans et al.
Joey J. Voermans et al.
Joey J. Voermans et al.Metrics will be available soon.