A mesoscopic numerical study of sea ice crystal growth and texture development

摘要

Development of sea ice polycrystals is simulated in two and three dimensions by a simple and efficient simulation technique, so-called Voronoi dynamics. First, effects of salt diffusion and heat flux are ignored and mutual impingements of stellar-shaped crystals are simulated in three-dimensional space. The simulated crystal texture and its c-axes distribution as a function of depth from the sea surface are shown to be in good agreement with experimental results. Next, three simulations are performed with different sets of parameters for growth rate in the basal plane. The obtained results show that geometrical selection of c-axes is more significant in weak anisotropy of growth rate in the basal plane than in strong anisotropy in the basal plane. However, the effect of the anisotropy on geometrical selection is modest. Effects of salt diffusion with time and salt rejection from growing ice to the ice-seawater interface as well as ocean heat flux are then incorporated into two-dimensional simulations. The results show that grains branch into thin ice platelets due to the relatively slow diffusion process during their growth. When the effect of heat flux is taken into consideration, the platelets align in the vertical direction, and homogeneous columnar ice is formed. These results are in accordance with microstructural features of real sea ice.