Measurement of the pressure and velocity field below surface waves

TLDR: In this article, a tower in the Adriatic Sea near Venice in a water depth of 16 m was used to observe the wave elevation, pressure and three components of velocity.

Abstract: Observations of the wave elevation, pressure and three components of velocity have been made at different depths from a tower in the Adriatic Sea near Venice in a water depth of 16 m. The spectral analysis of the pressure measurements show significant differences from linear wave theory which depend on the wavelength and depth of the transducer. The velocity field was measured with two electromagnetic current meters in the same vertical line. The amplitudes of the vertical and horizontal velocities were about 10% less than expected on the basis of linear wave theory. The downward transport of horizontal momentum, estimated from the co-spectrum of the vertical and horizontal velocities, was found to be much greater than the total atmospheric stress. The large values of the momentum flux are associated with deviations in the phase of the horizontal velocity component with respect to the wave elevation from the value expected using linear wave theory.