Thermodynamic consolidation of ice ridge keels in water at varying freezing points

- We examine interaction of keel with water at varying freezing points.
- Such interaction leads to thermodynamic consolidation of ice ridge keel.
- Model shows considerable or even full consolidation under different scenarios.
- This process could explain summer transformation of first-year ice ridges.

The permeability of sea ice ridge keels to surrounding seawater was investigated using data from field measurements in the Barents Sea. Two models that describe the consolidation of ice rubble due to the penetration of low salinity water at freezing point inside the rubble were formulated and analyzed when the water salinity decreases with time. The sea ice enthalpy depends on the temperature and salinity with considerable increase towards the 0 °C. It is shown that this dependence significantly influences the amount of newly formed ice around the rubble. The presence of brine pockets in the sea ice explains such dependence. When sea ice is heated brine solution should adjust its salinity to stay in thermodynamic equilibrium with pure ice. Reduction of salinity in the closed pocket is possible due to melting of ice on the wall of the pocket. This latent heat of fusion defines so high specific heat capacity of sea ice and as a result allows extracting enough coldness from sea ice rubble to reach high values of its consolidation. It was shown that in both models a key role in consolidation is played by the process of interchange between microporosity of sea ice and macroporosity of rubble field.