Research On Decaying Law Of Oceanic Reverberation Intensity In Three Dimensions

Oceanic reverberation is one of the fiercest interference to the sonar, and it contains a lot of information of the ocean. So researches about oceanic reverberation is meaningful. Average intensity is one of the physical parameters which are used to describe the oceanic reverberation and the researches about it had been carried out a long time before, but not thoroughly yet. In this thesis, some useful techniques for average reverberation intensity decaying are given basing on the work which have been done by other researchers.When we calculates oceanic reverberation, the formula is more complexer if we considers all Multi-path. But in fact, some of the Multi-pat can be neglected because their proffer is not enough to the intensity of the oceanic reverberation. Based on Ray theory, we first induce the formula, which is used to culculate the average intensity of the benthal reverberation from different multi-path sound-rays. And on the basis of numeric calculations, we compare the relative intensities of the benthal reverberations of different sound-rays and analyze their different contributions to the total reverberation. Therefore, we can considers only fourth Multi-path and we can get the intensity of the oceanic reverberation more veraciouser.Second, the formula for average intensity of ocean reverberation is deduced on the basis of Ray theory for monostatic case, then it is proved by computer simulation. It is obvious that the decaying rule of average reverberation intensity is affected by scattering coefficient of sea floor, sound speed profile, inclination of bottom etc. The sea floor scattering function is the most important factor to the intensity decaying rule. The sound speed profile is another important factor. And the other factor to the reverberation intensity decaying is sea floor inclination, the greater the slope angle, the slower reverberation intensity decay.At last, the average intensity of reverberation for bistatic case had been deduced. The bistatic average intensity firstly rises with time to a top point, then it goes down, the greater the scattering coefficient of sea floor, the smaller reverberation intensity. Comparing to the data of experiments, the model of the bistatic reverberation can be forecasted intensity of the oceanic reverberation.