Glacier mass balance provides an important link between climate and changes in the size and shape or a glacier. Here the investigators propose a new concept for mass balance, the reference-surface' balance rate, which is independent of the changing geometry of a glacier. This is a three year project with two goals: (1) To define and to show the importance of this new type of balance, and to determine how to measure it within the context of conventional mass balance programs. (2) To improve the theory of the response of a glacier or ice cap to changes in climate. The first goal is motivated by the problem that the mass balance of a glacier depends not only upon climate, but upon the geometry of the glacier surface. This is a serious complication in finding a connection between balance and climate. The proposed reference-surface balance rate is directly connected with climate, and its measurement could become a part of ongoing balance programs. The second goal is an outgrowth of preliminary work on defining the reference-surface balance rate. It is a convenient starting point for several extensions of the theory of the response of a glacier to climate change. It includes the effects of the dependence of mass balance upon elevation and upon the three dimensional nature of the surface. The problems to be studied include the effects of a glacier's geometry on the stability and magnitude of its response to climate change, the effects of observed geometrical asymmetry during advance and retreat, and the possibility of deducing the reference-surface balance rate from conventional mass balance rate.
