Influence of a Warm Eddy on Low-frequency Sound Propagation in the East Sea

Abstract

It is well known that sound waves in the sea propagates under the influence of sea surface and bottom roughness, the sound speed profile, the water depth, and the density of sea floor sediment. In particular, an abrupt change of sound speed with depth can greatly affect sound propagation through an eddy. Eddies are frequently generated in the East Sea near the Korean Peninsula. A warm eddy with diameter of about 150 km is often observed, and the sound speed profile is greatly changed within about 400 m of water depth at the center by the eddy around the Ulleung Basin in the East Sea. The characteristics of low-frequency sound propagation across a warm eddy are investigated by a sound propagation model in order to understand the influence of warm eddies. The acoustic rays and propagation losses are calculated by a range-dependent acoustic model in conditions where the eddy is both present and absent. We found that low-frequency sound propagation is affected by the warm eddy, and that the phenomena dominate the upper ocean within 800 m of water depth. The propagation losses of a 100 Hz frequency are variable within ±15 dB with depth and range by the warm eddy. Such variations are more pronounced at the deep source near the sound channel axis than the shallow source. Furthermore, low-frequency sound propagation from the eddy center to the eddy edge is more affected by the warm eddy than sound propagation from the eddy edge to the eddy center.

Effects of Warm Eddy on Long-range Sound Propagation in the East Sea

“…있다. [3] 해외의 경우 소용돌이의 발달 및 해양학적 특 성과 소용돌이가 음파전달에 미치는 영향에 대해 활 발하게 진행되어 왔다. [4][5][6] 국내의 경우 동해에 많이 발달하는 난수성 소용돌이에 대한 해양학적 연구는 많이 진행되어 온 반면에 [7,8]…”