Computational modelling of ice floe dynamics in the Antarctic marginal ice zone.

• Main Author: Marquart, Rutger
• Other Authors: Skatulla, Sebastian, Machutchon Keith
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Department of Civil Engineering 2023
• Subjects: Civil Engineering; Antarctic; The Antarctic; Antarc*; Sea ice
• Online Access: http://hdl.handle.net/11427/38051

The contribution of Antarctic sea ice in global climate models requires a more accurately estimation, as a relatively large part, approximately 4% of the Earth's surface in the winter season, is covered by sea ice. Understanding the dynamic and thermodynamic processes of sea ice, results in a better comprehension of sea ice behaviour in the Antarctic marginal ice zone (MIZ) and thus leads to better predictions. Large-scale sea ice models operate at regions of 10-100km2 , describing sea ice in a smeared model approach. However, the highly dynamic sea ice behaviour in the Antarctic MIZ, which is represented by the area where sea ice and ocean waves interact, still eludes reliable prediction. A heterogeneous morphology, consisting of relatively small and mobile ice floes, governed by collisional dynamics and fracture mechanics, requires detailed finer-scale sea ice dynamics models. Therefore, this project focuses on small-scale modelling of sea ice dynamics in the Antarctic MIZ. A more detailed model implies a heterogeneous sea ice material composition, considering separately ice floes and grease ice with their distinct properties. The material behaviour of ice floes is implemented using a Hookean-like flow rule, whereas grease ice is governed by a viscous-plastic material law. The small-scale model assumes that sea ice is isothermal, as only small time windows of less than a minute are considered. As a result, thermodynamic effects, such as sea ice melt and growth, are not taken into account. This work describes key aspects of ice floe collision dynamics in wavy conditions, considering skin drag, the Froude-Krylov force acting at the circumference of ice floes from the wave pressure gradient, and form drag due to the surrounding grease ice deeper into the Antarctic MIZ in a low to medium wave energy regime. Ice floes that interact with each other and the interaction between ice floes and grease ice are analysed. The behaviour of the sea ice rheology of both ice floes and grease ice are studied in realistic sea ice ...