Temperature dependence of the thermal conductivity of Antarctic sea ice

Abstract

Temperature measurements have been made in situ on Antarctic sea ice (during the Antarctic Winter) in order to obtain its thermal conductivity. The measurements were made using a series of thermistors spaced approximately 100 mm apart in a probe frozen in first-year sea ice in McMurdo Sound. The results showed significant anomalies in the behaviour of the thermal conductivity, including large scale convective effects. The thermal conductivity at low temperature gradients gave values that agreed with the higher theoretical predictions, with values for k ranging from ~ 1-92 Wm-1K-1 to ~ 2.42 Wm-1K-1, with an average value of ~ 2.17±0.12Wm-1K-1. At higher temperature gradients (|dT/dz| >~ 12°C/m)the thermal conductivity calculated using the relationship ∂U/∂t vs.∂2T/∂z2 rose above the theoretical maximum. The behaviour of the thermal conductivity showed strong deviations from linear behaviour and the presence of a hysteretic loop structure that leads to the hypothesis that the anomalies are due to convection in brine inclusions. Further analysis supports this hypothesis and furthermore shows that not only does convection take place but it also augments the transportation properties of brine through both the vertical and horizontal directions.