Abstract:

The melting of Arctic summer sea ice is accelerating, and studies have shown that the ice melting pool significantly contributes to the positive feedback effect of sea ice melting. However, there is relatively little research on the ice melting layer and its impact on sea ice melting. This study used a low-temperature laboratory to simulate the temperature in the polar region, and conducted experimental research on the effect of different thicknesses of ice meltwater layers under 20 cm and 40 cm of ice on the melting of overlying artificially frozen 20-cm-thick saline water at an ambient temperature of 10 ℃ The heat flux at the ice water interface was also analyzed. The results indicated that: (1) the depth of the freshwater layer was positively associated with the speed at which the saltwater ice melted. Under laboratory conditions, the average melting rate of the freshwater layer was 0.115 cm·h^–1 at a depth of 20 cm and 0.140 cm·h^–1 at a depth of 40 cm, resulting in a difference of approximately 17.86%. (2) The overall average water temperature of the freshwater layer at a depth of 40 cm varied more uniformly over time compared with that of the freshwater layer at a depth of 20 cm. (3) The latent heat flux of the freshwater layer was 92.4 J·(s·m²)^–1 at a depth of 20 cm and 112.4 J·(s·m²)^–1 at a depth of 40 cm, resulting in a difference of approximately 17.8%. The melting process was mainly affected by the latent heat flux. The study findings indicated that the depth of the ice melting layer had a certain impact on the melting of overlying sea ice. This information will provide support for further research on the evolution of Arctic sea ice melting pools.

Key words: melting layer, Arctic sea ice, melting rate, temperature distribution, heat flux