CALCULATION OF SHALLOW WATER REVERBERATION INTENSITY BASED ON RAY THEORY, PART （Ⅱ）

The method used for calculating the long range reverberation intensity in shallow homogeneous layer had been described in part I. It will be extented to include the inhomogeneous layer consisted of two isovelocity layers L¹ (near the bottom), L³(near the surface) and a gradient layer L² (Located between L¹ and L³) in this paper.
The rays in this mixed layer may be divided into two classes according to whether they can penetrate through the gradient layer L². Considering the faet that, at long ranges, the grazing angles of all effective rays would be small, thie grazing angles needed to caleulate the reverberation can be obtained approximately for both elasses. Then the bottom and the surface reverberation intensities I_3b⁺、I_3b^- and I_3s⁺ are calculated analytically, as the projector and the receiver are at thle same place in layer L_s (the sign "+" or "-",means the velocity gradient a> >0 or a< 0).The results for adequate long range show that I_3b⁺~r^-7/2 (for the omnidirectional scattering),-r^-4 (for the lambert's scattering),I_3b^-~r^-5 (for both sciattering) and I_3b⁺~r^-1 (for the omnidirectional scattering).
A similar caleulation can be carried out as well for the case the projector and the receiver are at the same place in L₁, and no more difficulties will exist.