Institute of Applied Marine Physics and Undersea Technology, National Sun Yat-sen University, No. 70, Lienhai Road, Kaohsiung, 80424, Taiwan.
J Acoust Soc Am. 2013 Aug;134(2):EL198-204. doi: 10.1121/1.4812862.
The large subaqueous sand dunes on the upper continental slope of the South China Sea are expected to couple acoustic propagating normal modes. In this letter, the criterion of adiabatic invariance is extended to the case of a waveguide possessing bedforms. Using the extended criterion to examine mode propagation over the bedforms observed in the sand dune field in 2012, results demonstrate that bedforms increase mode coupling strength such that the criterion for adiabatic propagation is exceeded for waveguides with small bedform amplitude to water depth ratios; increasing bedform amplitude enhances mode coupling. Numerical simulations confirm the extended criterion parameterization.
南海陆坡上部的大型水下沙垄预计会耦合声波传播的正常模式。在这封信件中，绝热不变性准则被扩展到具有床形的波导的情况。使用扩展的准则来检验在 2012 年沙垄场观测到的床形上的模式传播，结果表明，床形增加了模式耦合强度，使得对于小床形振幅与水深比的波导，绝热传播的准则被超过；增加床形振幅会增强模式耦合。数值模拟证实了扩展准则的参数化。
