HR: 08:15h
AN: C51C-02 INVITED     [Abstracts]
TI: Thermal Conductivity of Sea ice: Measurement and Modelling Parameterisation
AU: * Pringle, D J
EM: Daniel.Pringle@vuw.ac.nz
AF: Victoria University of Wellington, PO Box 600, Wellington, 6001 New Zealand
AU: Trodahl, H
EM: Joe.Trodahl@vuw.ac.nz
AF: Victoria University of Wellington, PO Box 600, Wellington, 6001 New Zealand
AB: The thermal conductivity is a fundamental parameter in sea ice modelling, but due to measurement difficulties is usually represented by simplified parameterisations or a constant value. We report new results from our program to measure the thermal conductivity of sea ice ($k_{si}$), new insight into previous results, and a comparison of our results with the common parameterisations used in sea ice modelling. The measurement is based on two different experiments. The first is based on temperatures recorded with thermal arrays in first year sea ice in McMurdo Sound, Antarctica and off Point Barrow, Alaska. From time-series analysis of these temperatures we have determined the depth- and temperature- dependence of ksi. Previous such analysis has suggested an unexpected decrease in the conductivity of first year ice of 25-50% over the top 50cm. We also report on a second, direct method for measuring the thermal conductivity of small sea ice cores in which we observe no difference in the conductivity of surface (0-10cm) and sub-surface (45-55cm) ice. Furthermore, we show that analytical artefacts might explain the apparent near-surface reduction in the array measurements, as well as other observed features. From our measurements we resolve the temperature dependence of $k_{si}$(T), and compare it with theoretical models and the 1964 parameterisation of Untersteiner which is commonly used in sea ice models. We discuss that scheme and possible amendments.
DE: 4207 Arctic and Antarctic oceanography
DE: 4271 Physical and chemical properties of seawater
DE: 4294 Instruments and techniques
SC: Cryosphere [C]
MN: 2004 AGU Fall Meeting