Variations of δ 18 O in the snow which accumulates at a Nordic temperate glacier during the winter are not entirely eliminated after a few months of ablation in the following summer. Survive of isotopic signals close...Variations of δ 18 O in the snow which accumulates at a Nordic temperate glacier during the winter are not entirely eliminated after a few months of ablation in the following summer. Survive of isotopic signals closely relates to the re\|freezing capacity of snow accumulated in winter when its temperature was below 0 ℃. The melt\|water re\|freezing ice layers formed in winter hindered subsequent melt\|water percolation in summer when snow temperature was at melting point and, therefore, varied isotopic record was reserved between these ice layers. The isotopic record in snow pack can provide an estimate of the approximate trend of the most recent winter season temperatures. The relationship between regional temperature changes and δ 18 O values in the snow pack is affected by many natural factors, but 1989\1990 （a glacier balance year） winter air temperatures were reflected in the snow which remained on the glacier Austre Okstindbreen at an altitude of \{1 350\} m in July 1990. There was larger amplitude of variations of δ 18 O values in the 4.1 m of snow above the 1989 summer surface, but variations in the underlying firn were relatively small. Melt water percolation modifies the initial variations of δ 18 O values in the snow pack. At a site below the mean equilibrium line altitude on Austre Okstindbreen, increased isotopic homogenization within a ten\|day period in July accompanied an increase of the mean δ 18 O value. Although the isotopic record at a temperate glacier is likely to be influenced by more factors than is that at polar glaciers, it can provide an estimate of the approximate trend of recent local temperature variations.展开更多
文摘Variations of δ 18 O in the snow which accumulates at a Nordic temperate glacier during the winter are not entirely eliminated after a few months of ablation in the following summer. Survive of isotopic signals closely relates to the re\|freezing capacity of snow accumulated in winter when its temperature was below 0 ℃. The melt\|water re\|freezing ice layers formed in winter hindered subsequent melt\|water percolation in summer when snow temperature was at melting point and, therefore, varied isotopic record was reserved between these ice layers. The isotopic record in snow pack can provide an estimate of the approximate trend of the most recent winter season temperatures. The relationship between regional temperature changes and δ 18 O values in the snow pack is affected by many natural factors, but 1989\1990 （a glacier balance year） winter air temperatures were reflected in the snow which remained on the glacier Austre Okstindbreen at an altitude of \{1 350\} m in July 1990. There was larger amplitude of variations of δ 18 O values in the 4.1 m of snow above the 1989 summer surface, but variations in the underlying firn were relatively small. Melt water percolation modifies the initial variations of δ 18 O values in the snow pack. At a site below the mean equilibrium line altitude on Austre Okstindbreen, increased isotopic homogenization within a ten\|day period in July accompanied an increase of the mean δ 18 O value. Although the isotopic record at a temperate glacier is likely to be influenced by more factors than is that at polar glaciers, it can provide an estimate of the approximate trend of recent local temperature variations.
