Sea-bottom scattering waves in sound propagation at shallow water with a thermocline

Data of a sound propagation experiment in shallow water with a thermocline have been analysed.In the experiment explosive charges were detonated under the thermocline and two hydrophones were located respectively above and below the thermocline.At long ranges the signals received by the upper hydrophone are composed of two pats:signal propagating from the source to the receiver,which is consistant with the normal-mode calculations,and a late arriving stronger signal which however does not show up in the calculations.This latter pat of the signal can be explained by considering the bottom scattering induced by the sound waves propagating under the thermocline.In addition,from this pat of the signal it is possible to estimate the three dimensional bottom scattering characteristics.