Abstract
Glacial equilibrium line altitude (ELA) is an important indicator of regional climate conditions. Especially for the paleo-ELA, a number of previous studies have estimated it using Accumulation Area Ratio (AAR) implemented in the two dimensional glacial extents reconstructed by the various glacial geomorphological techniques. However, there is few verification from the viewpoint whether the reconstructed glaciers are appropriate dynamically or in mass balance. Thus, this study attempts to develop a three dimensional ELA estimation model. This model calculates mass balance at given cross sections of a glacier determined by bed and glacial surface morphology. The position of the section where positive/negative mass balance interchanges is regarded as its ELA. We verified this model using the currently existing glaciers in Switzerland and Sweden. As a result, the calculated ELA showed the same altitude as observed ones. In some case, ELA was detected by two or more altitudes of the glacier that has ice thickness changes along the flow line due to the bed topographic variation. These results show that the shape of glacier surface or bed topography serves as important parameters which influences reconstruction of paleo-ELA.
