珠穆朗玛峰北坡东绒布冰川成冰作用的新认识

冰川成冰作用的研究对于选择冰芯钻取点具有重要的科学意义.前人对珠穆朗玛峰北坡冰川成冰作用的研究,由于缺少高海拔区域的实测资料而具有一定的局限性.文章通过1998年东绒布冰川垭口处(6 500 m a.s.l.)11m冰芯和海拔6 450 m处20 m冰芯剖面的成冰作用过程研究,认识到由于水、热条件的逐年波动,冰川成冰作用也处于变化之中.珠穆朗玛峰北坡东绒布冰川高海拔区域,在一定的水、热条件下(如气温较低和降水量较大等),再冻结-重结晶作用依然占主导地位,该成冰作用至少在垭口部位是有分布的.而一般在气温较高或降水量较少等条件下,冰川的成冰作用则以冷渗浸-重结晶作用为主.

New Knowledge of Transformation of Snow to Ice in the East Rongbuk Glacier, Northern Slope of Mount Qomolangma (Everest)

Researches in transformation of snow to ice are significant for choosing ice coring site.Due to lacking of observed data at higher elevation,earlier studies on the transformation of snow to ice were very limited in the East Rongbuk Glacier,northern slope of Mount Qomolangma.During September,1998,the ice coring project has been carried out on the northern slope of Mount Qomolangma.The analysis of an 11 m ice core at the col(6500 m a.s.l.) and a 20 m ice core at an elevation of 6 450 m in the East Rongbuk Glacier indicates that transformation of snow to ice is varying annually,which may depend on variation of air temperature and precipitation amount.In the high elevation region of the East Rongbuk Glacier,the refrozen-recrystallization is dominant in transforming of snow to ice at the certain conditions,such as low summer temperature or high precipitation.In another word,the refrozen-recrystallization zone does exist in the East Rongbuk Glacier(at least at the col of the glacier).The cold percolation-recrystallization is major transforming process from snow to ice when summer temperature is high or precipitation is low.The result clarifies the uncertainties of transformation of snow to ice in the high elevation over the Himalayas.It also encourages us to recover ice cores that have reliable records from the accumulation area of glacier at the high elevation of the Himalayas.