Author(s): Daisuke Yamagishi; Pat J. Langhorne

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Abstract: Sea ice is never completely solid and forms a mushy layer (or skeletal layer) at the temperatures encountered in nature. The amount of liquid in the sea ice determines its physical properties. An effective estimate for the solid volume fraction, Φs during sea ice formation which is applicable for in situ measurements was first established by Shirtcliffe et al. (1991). They utilised the measurement of the electrical impedance of the mixture of the solid and the liquid and the conductivity of the liquid in the mushy layer. Improvements were made by Shirtcliffe and Kerr (1992) and Notz (2005); Notz et al. (2005). This research investigated Φs of sea ice with an improved device which measured the resistive and capacitative impedance for rapidly growing sea ice with various initial conditions. The results indicate the measurements made from the magnitude of the total impedance were in good agreement with the theoretical values of Φs which were obtained from the equations provided from Frankenstein and Garner (1967) and Wettlaufer et al. (2000). Experimentally measured Φs was within 0.05 to the theoretically estimated Φs. The results conclude that the skeletal layer thickness, and hence Φs, are a function of the growth rate of sea ice, and the greater the growth rate, the smaller the mushy layer thickness.

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Year: 2008