Evaluation of experimental techniques for determining the plane wave reflection coefficient at the sea floor

Abstract

One of the most commonly used techniques for determinati on of the geoacoustical properties of the sea bed is the measurement of plane wave reflection coefficients at the ocean bottom. An incident field is pr oduced by either an explosive source or a beam generating device and the reflected field is then detected by means of an array of hydrophones. The associated angles of incidence have traditionally been dete rmi ned by simple geometrical considerations. However such simple interpretations give results that in some cases depend on the actual exper imental geometry. For example critical angles can appear far away from the correct values or not be present at all. Here an exact numerical model i s used to examine the different experimental techniques. The observed dis crepancies are explained, both for the point and beam source experiments. In addit ion, guidelines are given for interpretation of results obtained by the different experimental techniques.