Validity of Two-layered Ocean Bottom Model for Ray Model

Keunhwa Lee; Woojae Seong

doi:10.7776/ASK.2015.34.6.470

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2015 Vol.34, Issue 6 Preview Page Next Page

Validity of Two-layered Ocean Bottom Model for Ray Model 음선 모델에 적용된 이층 해저 바닥 모델의 유효성

30 November 2015. pp. 470-478

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Abstract

A heuristic method treating a layered ocean bottom in a ray modeling is to use the plane wave reflection coefficient for multiple-layered structure, named an one-layer assumption in this paper. We examine the validity of one-layer assumption in the case of two-layered ocean bottom, and obtain a simple inequality condition depending on the sound speed ratio, the ratio of layer thickness to source-receiver range, and the grazing angle of first reflected ray. From this inequality condition, it is shown that an one-layer assumption can be applicable to ray propagation problems at mid frequencies. Finally, numerical experiments are performed in the ocean environment similar to the East Sea in Korea. Incoherent transmission loss is calculated by the geometrical beam model with the plane wave reflection coefficient for multiple-layered ocean bottom and compared with the result of SNUPE 2.0, which is a parabolic equation package developed in Seoul National University.

Keywords

Geometrical beam

Ray model

Plane wave reflection coefficient

Two-layered ocean bottom

One-layer assumption

음선 모델링에서 다층 해저 바닥을 고려하는 경험적 방법 중 하나는 단일층 가정으로써, 다층 구조에 대한 평면파 반사계수를 사용하는 것이다. 본 연구자는 이층 해저 바닥에 대해 단일 층 가정의 유효성을 조사하고, 음속비, 송수신 거리 당 층 두께, 1차 반사파의 스침각의 함수로 표현되는 간단한 부등식 조건을 얻었다. 부등식 조건으로부터, 단일 층 가정이 실제 해양 환경의 중주파수 음선 모델링에 적용될 수 있음을 보였다. 마지막으로 한국 동해와 유사한 해양환경에 대해 수치실험을 수행하였다. 다층 해저 바닥에 대한 평면파 반사계수를 적용한 기하학적 빔 모델을 이용하여 비상관 전달손실을 계산하고, 서울대학교에서 개발한 포물선 방정식 패키지인 SNUPE 2.0의 결과와 비교하였다.

키워드

기하학적 빔

음선 모델

평면파 반사계수

이층 해저 바닥

단일 층 가정

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Information

Publisher :The Acoustical Society of Korea
Publisher(Ko) :한국음향학회
Journal Title :The Journal of the Acoustical Society of Korea
Journal Title(Ko) :한국음향학회지
Volume : 34
No :6
Pages :470-478
Received Date : 2015-10-02
Revised Date : 2015-11-09
Accepted Date : 2015-11-12
DOI :https://doi.org/10.7776/ASK.2015.34.6.470

The Journal of the Acoustical Society of Korea ISSN:1225-4428(Print) 2287-3775(Online) 한국음향학회지

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