Abstract:

A snow/ics core of more than 60 m long borehole drilled at the Law Dome Ice Cap, Wilkes Land, Antarctica, has been studied. The characteristic variation in the densification of snow in the zone of borehole SGR is described in present work. More over, a regression analysis was made on this process. The results suggest that snow/firn density of the ice sheet increases, but the extent of increment is reduced with increasing depth . A cocept called "retardation of density variation "is proposed . The retardation of density variation for the site where the core was used in this study is -0. 156 kg/m3 · m2. The mean snow/firn densification rate before it becomes ice is 4. 08 kg/m3 · a . The critical points of density variation for the ice sheet is some different from those reported in previous works . In the analysis of this feature , the authors emphasize the effect of the temperature of ice sheet on the snow as it was still in the active layer. And the anomalous density variation and the picking up of its deviation are attribued to this mechanism too . It has been especially pointed out that in the polar region the densification feature ofsnow is significant in climatology. To some extent it provides an information on the climate variation when the snow cover was formed. The transition depth of snow to ice determined from the density variationis 50 m for the drill site , it is near the ice formation depth of snow discovered and reported by otyers from other territories of Antarctica .