Modelling Wave-Ice Interactions in the Marginal Ice Zone

Abstract:

Over the past decade, there has been a rapid growth of interest in wave propagation through ice covers in the marginal ice zone. This talk summarizes the author’s observation of the modeling efforts on this topic. Models can be theory-based, data-driven, or a combination of the two. Data-driven models rely on a large amount of observations and are only becoming available recently. Theory-based models have a long history. They are always a simplified version of the reality. As our knowledge grows, theories become more complicated. A theory for waves-in-ice that captures all possible processes does not exist. However, when integrated with observation through calibration, these combined theory+data models may be used with some confidence. Present theory-based models do not have the correct spectral attenuation trend as observed from field or laboratory experiments. Hence, through calibration they may fit different parts of the wave spectra but not all. Data-driven models can reproduce the correct trend, but their dependability outside the situation where the data are collected is uncertain. In this talk, different models, their basic concepts, their calibration and validation are discussed. While ice covers affect wave propagation, waves also affect ice covers. When new ice accumulates from frazil production in open water, in the absence of waves, nilas form. With sufficient wave intensity, frazil ice accumulates into grease ice that may evolve into pancake ice and eventually sheet ice as the waves damp. The type of ice in the marginal ice zone influences the rate of wave attenuation. Because different ice types have different surface roughness and albedo, they also affect momentum and energy transfer between the atmosphere and the ocean. This talk reviews some past studies concerning wave effects on the types of new ice. A conceptual framework is given that implements these ideas into a wave-ice interaction model.