Physics of seasonal sea ice (PSI)

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It is long known that surface gravity waves can propagate significant distances within the sea ice cover and contribute to its break-up into smaller pieces called floes. In the context of the rapid changes that we observe in Arctic sea ice, waves play an increasingly important role as longer fetch increase their energy and momentum and sea ice gets thinner. Yet, wave-ice interactions are barely included in numerical models used either for climate studies or operational met-ocean forecasting. There are numerous potential feedback processes involving waves and sea ice, the impact of which is difficult without adequate representation of the relevant physical mechanisms in numerical models. In order to make progress with models, however, there is a recognized need for new datasets that are commensurate with processes we want to understand and model. Despite the enormous progress realized and yet to come in satellite remote sensing of sea ice and waves, the temporal frequency and the spatial resolution isn't high enough to resolve the relevant scales. Results obtained form laboratory experiments performed in wave tanks are useful, but their applicability to natural environments remains limited. The proposed program's goal is to significantly advance our understanding and models of wave-ice interactions that heavily control seasonal sea ice. In particular, the proposed research will focus on i) frazil dynamics, ii) the evolution of the thickness and floe size distribution, iii) the wave energy and momentum balance in the marginal ice zone and iv) the influence of waves and floe size on sea ice rheology. The proposed methodology follows an iterative hypothesis-driven approach with two equally important and synergistic components. The first component is a series of field experiments to be carried annually during winter in the seasonally ice-covered St. Lawrence Estuary. Time-lapse cameras, drones, moorings and other instruments deployed on the ice with an ice canoe will provide datasets of unprecedented completeness. Observations will inform the development of parameterizations of wave-ice interactions to be tested in various model configurations, with different levels of realism. Ultimately, representing coupled wave-ice processes in numerical models has the potential to significantly increase the performance of short-term operational forecasting, seasonal and long-term climate projections. A long-term goal of this proposal is to deliver, in Canada, the first fully coupled atmosphere-ice-ocean-wave operational forecasting system that is effectively used for the safe planning of operations in polar and subpolar marine environments.