Ray and beam tracing in underwater acoustics

• Published in: The Journal of the Acoustical Society of America 2020-10, Vol.148 (4), p.2525-2525
• Main Author: Porter, Michael B.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.5147016

In 1919, Lichte published a paper on the influence of horizontal temperatures layers in sea water (his words). This paper is probably the first to use rays to understand sound propagation in the ocean and interestingly also predicts that deep water will provide “significantly greater ranges than in shallow water” anticipating later important discoveries about the deep-water sound channel. It is striking that ray modeling could be done in 1919. In the 1960s when digital computers assumed their central role in sound propagation, ray models were the inspiration. Over the following years many ray models were developed and every significant laboratory doing underwater acoustics had developed one. However, ray modeling is simple on one level, yet incredibly complex on others. A Navy report from 1985 concluded that they all had significant problems. In the following 30-odd years, other modeling approaches were pursued more aggressively; however, ray models had unique advantages and continued to evolve into modern beam-tracing methods. These new models are not free from the artifacts inherent in the ray approximation, but nevertheless are very powerful and significantly more accurate and reliable than their ancestors. Today they work. This talk will discuss the history and the state of the art.