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https://doi.org/10.5194/egusphere-2023-982
https://doi.org/10.5194/egusphere-2023-982
01 Jun 2023
 | 01 Jun 2023

Modelling ice mélange based on the viscous-plastic sea-ice rheology

Saskia Kahl, Carolin Mehlmann, and Dirk Notz

Abstract. Ice mélange, which is a mixture of sea ice, bergy bits and icebergs, can have a strong influence on the sea-ice–ocean interaction. So far, ice mélange is not represented in climate models as numerically efficient realizations are missing. This motivates the development of an ice-mélange model based on the viscous-plastic sea-ice rheology, which is currently the most commonly used material law for sea ice in climate models. Starting from the continuum mechanical formulation, we modify the rheology so that icebergs are represented by thick, highly compact pieces of sea ice. These compact pieces of sea ice are held together by a modified tensile strength in the material law. In this framework, the ice mélange is considered as one single fluid, where the icebergs are tracked by a volume in fluid method. Using idealized test cases, we demonstrate that the proposed changes in the material law are crucial to represent icebergs with the viscous-plastic rheology. Similar to the viscous-plastic sea-ice model, the ice-mélange model is highly nonlinear. Solving the model at the resolution needed to represent the typical size of icebergs in ice mélange (< 300 m) is therefore challenging. We show that the ice-mélange formulation can be approximated efficiently with a modified Newton method. Overall, the simple extension of the viscous-plastic sea-ice model is a promising path towards the integration of ice mélange in climate models.

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Saskia Kahl, Carolin Mehlmann, and Dirk Notz

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-982', Anonymous Referee #1, 14 Jul 2023
    • AC1: 'Reply on RC1', Saskia Kahl, 15 Nov 2023
  • RC2: 'Comment on egusphere-2023-982', Anonymous Referee #2, 14 Jul 2023
    • AC2: 'Reply on RC2', Saskia Kahl, 15 Nov 2023
Saskia Kahl, Carolin Mehlmann, and Dirk Notz
Saskia Kahl, Carolin Mehlmann, and Dirk Notz

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Short summary
Ice mélange is a mixture of sea ice and icebergs, which can have a strong influence on the sea-ice-ocean interaction. So far, ice mélange is not represented in climate models. We include icebergs into the most used sea-ice model by modifying the mathematical equations that describe the material law of sea ice. We show with three test cases that the modification is necessary to represent icebergs. Furthermore we suggest a numerical method to solve the ice mélange equations computational efficient.