关键词: Sea ice, lake ice, thermodynamics, thickness, temperature, Antarctica

Abstract:

Thermodynamic processes of lake ice in three lakes and landfast sea ice around Zhongshan Station, east Antarctica have been observed in 2006. The mass balance of lake ice was compared with that of landfast sea ice. The responses of lake-ice and sea-ice temperatures at varying depths to the local surface air temperature were explored. The vertical conductive heat fluxes at varying depths of lake ice and sea ice were derived from the vertical temperature profiles. The freeze-up of lake ice and landfast sea ice occurred from late February to early March. The maximum lake-ice thicknesses occurred from late September to early October, with the values of 156–177cm. The maximum sea-ice thicknesses with the values of 167–174cm occurred relatively later, i.e. from late October to later November. The temporal variations of internal temperatures for both lake ice and landfast sea ice were laggard compared with those of local surface air temperatures. The high-frequency variations of local surface air temperature were 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 the deeper ice layer than for the upper ice layer, which induced a smaller conductive heat flux through sea ice than lake ice at the same depth and under the same atmospheric forces, and a smoother fluctuation in the conductive heat flux for the deeper ice layer than for the upper ice layer. The enhanced desalination during the melt season consequently led to increase the melt point temperature within sea ice, which also made it different from fresh lake ice.

Key words: Sea ice, lake ice, thermodynamics, thickness, temperature, Antarctica