Estimates of coherent reflection loss inclusive of the effects of near-surface bubbles on sound speed

Abstract

Through simplification of the authors’ model “JBZ” of coherent reflection loss at the ocean surface, a revised model has been obtained in extremely simple form. This model provides descriptions of the loss obtained at a wind-roughened surface, adhering to a Pierson-Moskowitz surface wave frequency spectrum, inclusive of the effects of near-surface bubbles on sound speed. A very compact form of the model has been obtained for application to surface ducted sound for a wide range of wind speed and frequency combinations, with the result that the dB loss with range is the same for all modes within the duct. The derivation of the model from the authors’ earlier JBZ is described, and the conditions for equivalence are detailed. In a limited range of comparisons, descriptions of reflection loss per bounce obtained with the original JBZ and the compact version are shown to be nearly identical to corresponding values obtained by the “Relay” model described by Ainslie [JASA 118, 3513–3523 (2005)]. Through simplification of the authors’ model “JBZ” of coherent reflection loss at the ocean surface, a revised model has been obtained in extremely simple form. This model provides descriptions of the loss obtained at a wind-roughened surface, adhering to a Pierson-Moskowitz surface wave frequency spectrum, inclusive of the effects of near-surface bubbles on sound speed. A very compact form of the model has been obtained for application to surface ducted sound for a wide range of wind speed and frequency combinations, with the result that the dB loss with range is the same for all modes within the duct. The derivation of the model from the authors’ earlier JBZ is described, and the conditions for equivalence are detailed. In a limited range of comparisons, descriptions of reflection loss per bounce obtained with the original JBZ and the compact version are shown to be nearly identical to corresponding values obtained by the “Relay” model described by Ainslie [JASA 118, 3513–3523 (2005)].