| Abstract: | Ocean waves are often measured using sub-surface pressure transducers. The transfer function, relating pressure fluctuations to variations in water-surface elevation, is usually based on linear wave theory, with an empirical correction factor being applied to account for non-linearities.This paper is concerned with the determination of surface-elevation spectra from pressures recorded beneath irregular waves travelling on a current. Predicted spectra are compared with spectral densities calculated from measurements using a surface-piercing wave gauge. Results show that significant errors arise if the Doppler effect, associated with the presence of the current, is ignored. The importance of selecting appropriate values of the empirical correction factor is also demonstrated. |
