中天山平顶冰川物质交换特征——以格里戈里耶夫冰川为例

The Peculiarities of Mass Exchange of the Flat-top Glaciers at the Central Tianshan

平顶冰川在很大程度上反映了物质交换的区域特征。格里戈里耶夫平顶冰川所处的中天山地区,夏季固态降水量最大(约占年降水总量的80%),使冰川表面经常保持高的反射率,有利于4500m以上的冰川区不断收入物质。由于渗浸冻结成冰作用在夏季期间占有大的份额,融水不能全部变为径流,而部分补给了冰川。以附加冰形式保留在冰川上的融水份额,在消融期间的变化是,1987年7月前半月为57％,后半月为48％,8月前半月为11％。研究格里戈里耶夫冰川物质平衡形成过程,可由确定短时间间隔内的物质平衡各分量而获得。格里戈里耶夫冰川年物质平衡1986—1987年为+21.7g/cm^2,1987—1988年为-29.1g/cm^2。

Flat-top glaciers reflect main regional features of mass exchange. Their location at the upper level of the mountain chains within the reach of the precipitation from all directions, and absence of avalanche snow supply define that peculiarities. At the flat-top glaciers of Central Tianshan the summer maximum of solid precipitation (about 80% of the annual quantity) provides the constant large albedo at the surface of glaciers and leads to continuous increase of accumulation within the area above 4 500 m. The typical feature of such type of glaciers is that the runoff is not equal to the total amount of melting water due to infiltration-congelation. The part of water remaining in the glacier's body as superimposed ice decreases during the ablation period from about 57% at the first part of July to 48% at the second part of July and to 11 % of the total amount of melting water at the first half of August. Some processes of mass balance were researched by determining all the components of mass balance during short intervals. Mass balance of Grigoriev glacier-one of the flat-top glaciers of Central Tianshan was in 1986-1987 +21.7 g/cm2 and in 1987-1988 -29.1 g/cm2.