title: Relating waveguide invariant and bottom reflection phase-shift parameter P in a Pekeris waveguide.
abstract: The waveguide invariant β is affected by the shallow-water environment. The effect due to bottom sediment on β is investigated in this paper. It is found that the effect of sediment bottom can be concentrated on one parameter P-the bottom reflection phase-shift parameter. For a Pekeris waveguide, under Wentzel-Kramers-Brillouin (WKB) approximation, a very simple analytic relation is given: β ≈ 1 + P/(k(0)H(eff)), where H(eff) is the "effective depth," and H(eff) = H + P/2 k(0). The value of β related to different high-speed sediments (including layered sediment) ranges from 1.0 to 1.5. Some numerical examples including the layered sediment case are conducted to verify this result. Good agreement between the results calculated by KRAKEN and by WKB with parameter P has been found. Hence, the application of parameter P provides a model-free platform to investigate the bottom effect on the waveguide invariant β in shallow-water.
authors.affiliation: Key Laboratory of Underwater Acoustic Environment, Institute of Acoustics, Chinese Academy of Science, No 21, Bei-Si-Huan-Xi Road, Hai-dian District, Beijing 100190, People's Republic of China. ecshang32@aol.com
authors.forename: E C
authors.initials: EC
authors.lastname: Shang
authors.forename: J R
authors.initials: JR
authors.lastname: Wu
authors.forename: Z D
authors.initials: ZD
authors.lastname: Zhao