Formation of brine channels in sea-ice

TL;DR

This paper develops a phase field model to describe the microscopic formation of brine channels in sea ice, linking structure formation with freezing dynamics and validating with X-ray tomography data.

Contribution

It introduces a coupled phase field model with three parameters to simulate micro-structure formation in sea ice during solidification.

Findings

Model accurately predicts micro-structure patterns during freezing.

The structure formation depends on phase diagram and supercooling regions.

Comparison with X-ray CT shows good agreement with simulated structures.

Abstract

Liquid salty micro-channels (brine) between growing ice platelets in sea ice are an important habitat for $CO_2$ - binding microalgaea with great impact on polar ecosystems. The structure formation of ice platelets is microscopically described and a phase field model is developed. The pattern formation during solidification of the two-dimensional interstitial liquid is considered by two coupled order parameters, the tetrahedricity as structure of ice and the salinity. The coupling and time-evolution of these order parameters are described by a consistent set of three model parameters. They determine the velocity of the freezing process and the structure formation, the phase diagram, the super-cooling and super-heating region, and the specific heat. The model is used to calculate the short-time frozen micro-structures. The obtained morphological structure is compared with the vertical brine pore space obtained from Xray computed tomography.