11 August 2021, by Franz von Bock und Polach, Marco Klein und Moritz Hartmann
Photo: Franz von Bock und Polach
The interaction of waves and ice is a topic of increasing relevance for the fields of marine engineering, oceanography and climate sciences. Special interest is dedicated to the propagation of waves in ice-covered regions, for example the change of the dispersion relation and wave damping as well as the break-up of ice. The global warming and the related reduction of ice thickness also diminish the resistance of the ice to wave-induced break-up. At the same time, the reduced ice extent increases the fetch length for wind-generated waves. Along with other effects due to climate change, such as increased storm activity in the Arctic, wave-induced break-up of ice is expected to be triggered strongly by climate change. However, all of the above mentioned physical effects still contain a significant number of knowledge gaps.
In addition to wave break-up near the ice edge, it has been observed that wave-related break-up events also take place deep inside the solid ice far away from the ice edge. This is difficult to explain with linear theory in combination with the established exponential attenuation of the wave field. It has been shown theoretically that nonlinear effects can be triggered and intensified by solid ice as decreasing wave lengths under such ice condition result in the steepening of the waves.
In order to shed more light onto these occurrences, a research project has been funded by the German Research Foundation (DFG, project 407532845). The aim is to show numerically and experimentally that nonlinear wave-ice interaction can take place under solid ice, explaining ice-breakup processes far away from the ice edge. The small-scale experiments are conducted at the large ice basin of the Hamburg Ship Model Test Basin (HSVA), where wave properties are measured before entering the ice sheet and during their progression through the ice sheet. In the context of this project, it is also investigated how the production of the scaled ice is to be designed to avoid scale effects introduced by ordinary model ice used for ship-ice interaction experiments.
On the topic, Franz von Bock und Polach and Marco Klein are currently guest editors for a special issue of the Journal Water on "The Occurrence, Physics and Impact of Wave-Ice Interaction". The call for papers is open until the end of 2021.