Abstract:

Thermodynamic processes of lake ice in three lakes and landfast sea ice around Zhongshan Station, east Antarctica have been investigated in 2006. The growth and decay processes of lake ice are compared with those of landfast sea ice on the basic of in situ data. The responds of lake-ice and landfast sea-ice temperatures at varying depths relative to the time series of local surface air temperature is explored. The vertical conductive heat fluxes at varying depths of lake ice and sea ice were derived from the vertical ice temperature profiles. The freeze-up of lake ice and landfast sea ice occurred from late Feb. to early Mar. The maximum lake-ice thicknesses occurred from late Sep. to early Oct., with the values of 156–177cm. The maximum sea-ice thicknesses occurred relatively later, which occurred from late Oct. to later Nov., with the values of 167–174cm. The temporal variations of internal temperatures for both lake ice and landfast sea ice were laggard compared to those of local surface air temperature. The high frequency fluctuation of local surface air temperature was attenuated by ice cover evidently. The temporal lag and the high-frequency attenuation were more significantly for sea ice than for lake ice, and more distinct for lower ice layer than for upper ice layer, which induced a larger conductive heat flux for sea ice than for lake ice, and a lower level fluctuation in the conductive heat flux for lower ice layer than for upper ice layer. The enhanced desalination during the melt season was consequently increases the melt point temperature for sea ice, which also made it different from fresh lake ice.

Key words: Sea ice, lake ice, Thermodynamics, Thickness, Temperature, Antarctica