Uncertain Effects of Linear Internal Waves on Convergence Zone Propagation in Deep Water

Abstract

Zhang, L.; Chen, W., and Liu, D., 2020. Uncertain effects of linear internal waves on convergence zone propagation in deep water. In: Zheng, C.W.; Wang, Q.; Zhan, C., and Yang, S.B. (eds.), Air-Sea Interaction and Coastal Environments of the Maritime and Polar Silk Roads. Journal of Coastal Research, Special Issue No. 99, pp. 296–309. Coconut Creek (Florida), ISSN 0749-0208.The use of the convergence zone effect is an important means of underwater long-range target detection. Many uncertain factors (ocean fronts, ocean eddies, etc.) can lead to uncertainties of the sound field in the convergence zone. Linear internal waves are usually produced in the deep ocean, causing fluctuations of the sound velocity which are otherwise stable. Over long distances, linear internal waves will have a great influence on the propagation of sound waves. In this paper, a model of sound velocity fluctuation caused by linear internal waves is established, and the sound velocity field within a certain depth and distance range is obtained. The transmission loss is calculated using the ray mode parabolic equation underwater sound propagation model. The Monte Carlo method is then used to simulate the uncertainty of the sound field in the generated convergence zone. The results shows that the loss of sound propagation varies greatly when an internal wave propagates through the convergence zone. The uncertainty of the sound field in different convergence zones varies, and the uncertainty of the sound field increases with convergence zone range.