Digital Sea Ice Physics - A novel approach for computing and parametrising sea ice properties for geophysical applications

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• Sønke Maus (Norwegian University of Science and Technology)
• Wednesday 21 April 2021, 14:00-15:00
• British Antarctic Survey, Zoom.

If you have a question about this talk, please contact Dr Irena Vankova.

One of the large challenges in sea ice science is how sea ice properties (e.g., albedo, thermal conductivity) on small scales influence properties and processes on larger scales (e.g., the floe or ridge scale and basin-scale sea ice behaviour). To make progress one has to understand the variability in small-scale properties which can span several orders of magnitude (e.g. permeability). For many properties a strong dependence on temperature and salinity has been found, yet the detailed physical processes leading to this variability have remained unclear: On the one hand are the bulk fractions of sea ice constituents (gas, ice, brine and solid salts) often insufficiently known or measured. On the other hand, there is the lack in observations of 3D sea ice micro-structure to which the physical properties are related.

In the present talk I will focus on the concept of “Digital Sea Ice physics” to improve our understanding of sea ice properties, their dependence on microstructure and growth conditions, and illustrate several applications to geophysical sea ice problems. The concept is adopted from rock science where it has been established as “Digital Rock Physics” (DRP) during the last decade. It is based on 3D X-ray tomographic imaging and digitizing of the sea ice pore space, followed by direct numerical computation of its effective physical properties. In this way the relationship between effective physical properties of sea ice and its bulk constituents (volume fractions of ice, air, brine and solid salts) is determined and related to micro-scale characteristics of the pore space, providing an improved understanding of the properties’ variability.

I will begin the talk with an overview of sea ice properties and microstructure and their variability, to illustrate related challenges and open questions in sea ice science, identifying the need of 3D microstructure information for many topics. I will then describe the work flow of “Digital Sea Ice Physics” from field sampling to physical property computations, as well as the challenges for the porous medium sea ice, when compared to rocks and snow. I will discuss several applications to obtain sea ice properties that are relevant for sea ice and climate modelling: (i) transport properties of sea ice and recent results on sea ice permeability and electrical conductivity; (ii) the microstructure at the sea ice ocean interface (with relevance for on ice-ocean heat, salt and momentum exchange as well as ice-ice friction) and (iii) the ice surface regime (with relevance for albedo and inter-facial processes between sea ice and snow). Digital Sea ice physics is a concept that has large future potential due to increasing computational power to handle large 3D images. The talk closes with an overview of climate-relevant sea ice properties for which the approach opens new paths to fundamental knowledge and understanding.

This talk is part of the British Antarctic Survey - Polar Oceans seminar series series.

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