Determination of the rate of dissipation of turbulent energy near the sea surface in the presence of waves

The hot-film anemometer and its associated electronics have now been brought to a high level of performance and reliability. Enough measurements of one-dimensional turbulent spectra have now been obtained to establish with sufficient reliability the form of the high-wave-number spectrum. According to the Kolmogoroff hypothesis, this form is universal in shape and its scaling parameters depend only upon the kinematic viscosity v and the rate of energy decay per unit mass ∈. Thus, when v is known, measurement of any part of the spectrum permits determination of ∈. In the presence of masking noise, an upper limit may be placed on ∈. These concepts are illustrated with some measurements taken near the sea surface in the presence of waves.