High frequency acoustic imaging in the ocean

The use of acoustical techniques in oceanography is well known. Traditional applications have concentrated on long range, low frequency propagation. Due a convergence of both technology and national interests, consideration of the possibilities for creating high frequency, real time, multi-dimensional imaging systems (2 and 3-D) has emerged. Unfortunately, due to a lack of experimental investigation, the propagation issues related to these frequencies are relatively unknown. The authors´ group in underwater acoustic imaging applied to ocean exploration and oceanography has been taking high frequency acoustic pictures in the ocean for almost a decade. The first experiences were in using the traditional types of ocean going sonars such as side scans. More recently they have been developing a 3-dimensional multibeam imaging system for tracking small animals in the sea. As part of this effort they have been looking at both the spatial and temporal correlation scales for the propagation of high frequency sound