Global Model for Sound Absorption in Sea Water: Impact Study. Part 1

摘要

This report examines the impact of the model on sonar performance and the surface and bottom-loss models upon which predictions are currently based. The present analysis is limited mainly to active systems operating in the frequency range 3-4 kHz. The four regions examined are: North Atlantic, North Pacific, Eastern Mediterranean and Norwegian Sea. Comparison of K model predictions with those based on the Thorp formula indicates that two-way path absorption for the first CZ zone ranges from approximately 4 dB less in the North Pacific to 12 dB greater in the Eastern Mediterranean. In the bottom-bounce mode, these values are reduced roughly in proportion to range. The MGS bottom-loss model is based on analysis of one-way paths using the Thorp formula. The difference between the K model and Thorp formula for 10 degree grazing angle in the Eastern Mediterranean is roughly 4 bB, making the actual bottom-loss smaller by about on province number. the differences decrease with increasing grazing angle and are smaller in the other areas. Corrections to the MGS model should therefore be relatively minor. (JHD)