Hassan B. Ali
Code 7173, Naval Res. Lab., Stennis Space Center, MS 39529-5004
As a result of complex oceanographic and atmospheric processes in littoral regions, environmental parameters are characterized by considerable spatial and temporal variability. The preceding imposes severe constraints on signal processing schemes, thereby adversely influencing systems based on acoustical, optical, magnetic, and oceanographic parameters. Acoustic signals are degraded by extensive interaction with the surface and bottom boundaries, the passage of internal waves, tidal changes, ambient noise, the influx of fresh water from rivers and marshes, etc. It is unlikely that these diverse phenomena will all be present in any single geographic area. Rather, the number and significance of the phenomena will vary from site to site. As a result, it is important to identify and characterize the germane ocean processes and environmental features at particular sites of interest, in order to isolate and assess their acoustic effects. The objectives of this task are to ascertain the minimum number of oceanographic parameters controlling the acoustic propagation, and their requisite spatial and temporal resolutions. The results of such investigations for two diverse sites off the U.S. and U.K. coasts are provided in this paper.