Author(s): Toshiyuki Kawamura
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Abstract: Mechanical properties of sea ice strongly depend on distribution and concentration of brine drainage channels as well as bulk salinity in sea ice. Brine channel distribution was examined in sea ice experimentally grown from seed ice crystals with known crystallographic orientations. Investigated was dependence of the distribution on growth rate, relative difference of crystallographic c-axes of the two adjacent single crystals and their grain size. At an ice growth rate of 1.4 x 10~ m/s (0.5 mm/hr), distinguished tree-like structure of brine channels was not found independent of crystallographic arrangement and size of the seed crystals, and brine was drained away not from specific points but from the whole growing interface. On the contrary, at a higher growth rate of 2.8 or 5.6 x 10-7m/s, definite brine channels were recognized on favored grain boundaries at almost constant intervals, which were slightly shorter than those in natural sea ice. The channel interval tended to decrease with increasing c-axis inclination angle of the adjacent grains to the horizontal plane. Dependence of the interval on the grain size was not found clearly. Brine channels were formed initially on the intersection of grain boundary and protrusion on the winding ice-water interface.
Year: 1988