Short-range transmission loss and the evidence for bottom-refracted energy

Transmission loss over the range of the direct arrival is examined for a receiver lying on a deep, sedimentary ocean bottom and is found to exhibit interference structure not explained by water-borne paths alone. It is suggested that this structure can be understood in terms of energy refracted through the sediments back to the receiver. The velocity structure in the sediments required to account for the interference is quite consistent with the velocity structure inferred from seismic profiling the vicinity of the receivers.