1966 年 22 巻 5 号 p. 257-264
The refraction of sound waves in a 170m layer depth surface sound channel in the ocean is calculated by the ray theory employing somewhat simplified approximate equations (2. 8), (2. 9) and (2. 10). The depth of the bottom of the channel and the vertical gradient of the sound velociy in the channel are assumed to be 170m and +0, 015sec^-1 respectively. The reflected waves from the bottom of the ocean are neglected. The depths of the source of sound are changed by 20m steps from the surface to the depth of 160m. The rays of sound for each source depth are shown in Figs. 1, 2, . . . and 9 for the horizontal distances up to 25km and at 20' steps of the initial direction of propagation, including the up-going waves (dotted lines) and the down-going waves (solid lines) at the source. Formation of the caustics and the existence of the shadow zones are clearly indicated. It is also proposed that the sound indensity at long distances from the source in a surface sound channel, where tha ray density is uniform, will be approximately calculated by the equation (4. 1). These results will be very useful also for practical applications in underwater acoustics.