Acoustic modelling in SOFAR: application to interpretation of GASTOM 90

High frequency acoustic propagation in SOFAR gives complex systems of caustics at large distance. So the classical high frequency techniques, like geometrical optics, must be used with care. The Gaussian beam summation method is a high frequency approximation which remains valid in the vicinity of the caustics. The authors' purpose is to show the possibility of this method for underwater acoustic propagation. An application for acoustic analysis of GASTOM 90 experiment is done. The sound velocity distribution is simulated from the experimental sound speed profiles to obtain conditions closely related to Gastom 90. The authors assumed that the propagation medium is smooth, deterministic and the medium is well defined by horizontal samples of experimental profiles. The acoustic signal is modified when they take in account range dependence for the velocity distribution. >