Detection and analysis of breaking wind-waves with passive acoustics

The sounds emitted by breaking wind-waves have been measured and analysed for more than half a century (e.g. Knudsen et al. 1948, Terrill and Melville 2000). Breakers create bubbles ranging from centimetres to fractions of a millimeter and these bubbles in turn create sounds. Ocean-surface bubbles affect submarine sound propagation (Knudsen et al. 1948), remove CO2 from the atmosphere (Sabine et al. 2004) and dissipate oceanic energy (Babanin et al. 2001), which is of fundamental importance to the physics of the upper ocean. This paper briefly reviews some issues and a method of analysing breakers using the sound they emit.