Automated mapping of local layer slope and tracing of internal layers in radio echograms

Abstract

An automated method is presented for tracing layers in radio echograms. The method is designed to work with most radio-echo sounding echograms and has been successfully tested with a 180-210MHz multichannel coherent depth sounder. To accurately trace layers, first approximate layer positions are calculated by integrating the local layer slope which is inferred by the intensity response to a slanted filter, then the positions are refined using an iterative optimization. The layers are traced using an active contour model or snake, which can be constrained to conserve both echogram features and smooth layers.With this technique it is possible to trace internal layers over distances of several hundred kilometers. The method was tested between two Greenland deep ice cores where the age-depth relation is known.