Modelling of sea surface coupled losses in surface duct propagation

Sea surface coupled loss is a combination of losses encountered by acoustic energy on its propagation inside surface duct. These losses arise due to reflection from rough sea surface, scattering from bubbles trapped in the duct, leakage of acoustic energy from surface duct. There are many theoretical models for sea surface reflection losses and empirical models for sea surface coupled losses. This paper presents a review of various theoretical and empirical models related to sea surface coupled loss. Measurements of sea surface coupled loss carried out in two separate deep water experiments in the frequency band 1.5-5.5 kHz and analysis of the results are presented. Attempts are made to fit these results with the models discussed in this paper.