Direct measurement of sea ice thermal conductivity: No surface reduction

Abstract

We present new laboratory measurements of the thermal conductivity of small cores of landfast first-year (FY) and multiyear (MY) sea ice from McMurdo Sound, Antarctica. The conductivity of surface (0-10 cm) and subsurface (45-55 cm) FY ice, 2.14 ± 0.11 and 2.09 ± 0.11 W m-1 K-1, respectively, and MY surface ice, 1.88 ± 0.13 W m-1 K-1, are all consistent with effective medium predictions for measured salinity, density, and temperature. In contrast with a previous result from thermistor array measurements in FY ice, the present measurements in FY ice show no conductivity reduction over the top 50 cm. We have reexamined the analysis of these previous array measurements and have identified analytical effects that rendered this analysis unreliable in the presence of high-frequency surface temperature variations and pronounced surface warming and cooling events. We conclude that this apparent near-surface conductivity reduction was an artefact. Copyright 2006 by the American Geophysical Union.