![]() For this reason, a large number of surface drift current measurements have been obtained over long periods, started by Shemdin (1972), Wu (1975, 1983), Churchill and Csanady (1983), and Bye (1988), and continued at present (e.g., Longo 2012 Longo et al. From the physical perspective, the drift currents are interesting due to their observability, availability for measurements, and possibility of theoretical description (e.g., Stokes 1847 Longuet-Higgins 1953 Craik 1982 Bremer and Breivik 2017, and references therein). Thus, studying and understanding this phenomenon, which was comprehensively described in the recent review by Bremer and Breivik (2017), is of physical and practical importance. Surface drift currents play a significant role in marine shipping, the spread of surface waste, and marine industry safety. The obtained results and problems related to measuring surface drift currents are discussed. For the first time, this ratio provides the dependence of wind-induced drift on the surface wave parameters. Considering the percentage of wave breaking Br, the wave age A, and the wave steepness Ϭ, the parameterization of U dw was obtained in the form U dw = (Br + ϬA) u *, which corresponds to the observations with a mean error of 10%. In our measurements, the ratio U dw/ u * varies systematically in the range of 0.65–1.2. In the case of wind waves, the wind-induced part of the surface drift U dw is compared with the friction velocity u *. No visible dependence on the breaking intensity is observed. In this case, the ratio U d/ U St varies in the range of 0.5–0.93 and slightly increases with decreasing wave steepness. ![]() The measured surface drift currents induced by mechanical waves U d are compared with the Stokes drift at the surface U St estimated by a well-known formula with an integral over the wave spectrum. Three cases were studied: (i) regular (narrowband) mechanical waves, (ii) irregular (wideband) mechanical waves, and (iii) wind waves. The measurements were made by using surface floats in a large tank with dimensions of 32.5 × 1 × 2 m 3. ![]() The empirical features of surface drift currents induced by both mechanical and wind waves are presented.
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