The Application of Optical Filtering in Coherent Light to the Study of Aerial Photographs of Greenland Glaciers

Abstract

The principles that underlie the analysis of aerial photographs using the coherent light from a laser are summarized, and then a study of such a filtering technique applied to an aerial photograph of Jakobshavn Isbræ is given as an example. Two systems of crevasses, respectively parallel and perpendicular to the direction of flow of the southern lobe of the glacier can be detected after filtering. These two crevasse systems were not apparent at first sight on the original photograph as they were obliterated by a network of curved crevasses. It appears that this latter network are not true crevasses, but surface undulations formed by differential ablation of bands of black (or blue) and white ice.