Profile and Heat Balance at the Bottom Surface of an Ice Sheet Fringed by Mountain Ranges

摘要

The profile of an ice sheet surrounded by mountains is calculated and, by means of heat balance considerations, the pressure melting point conditions of the bottom ice are examined. A circular ice sheet and an ice sheet which is infinitely long in one direction are considered. The approximate profile of the whole ice sheet is obtained by adding the profiles calculated for 3 regions: an outer glacier, drainage basin on the ice sheet at the head of each outlet glacier, and from the center of the ice cap to the drainage region of each outlet glacier. The fact that the heat lost down the temperature gradient is of the same order as the geothermal heat and the heat of sliding, makes it difficult to determine whether or not the bottom of the ice sheet is at the melting point at a particular location, causing uncertainty in profile calculation. It is concluded that the profile of an ice sheet is little influenced by the presence of encircling mountains, and that the bottom temperature of immature outlet glaciers ordinarily should be at the pressure melting point, thus enabling such glaciers to erode their beds. (Author)