EGU2020-5400
https://doi.org/10.5194/egusphere-egu2020-5400
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Empirical Parameterization of the Wind-induced Drift Currents

Vladislav Polnikov1 and Hongyu Ma2
Vladislav Polnikov and Hongyu Ma
  • 1Obukhov Institute of Atmospheric Physics of RAS, Air-Sea interaction, Moscow, Russian Federation (polnikov@mail.ru)
  • 2First Institute of Oceanography of MNR, Key Laboratory, Qingdao, China (mahy@fio.org.cn)

Results of measurements of the drift currents induced by waves and wind at the wavy water surface are presented. The measurements were executed by means of surface floats in a large tank with the dimensions of 32.5x1x2 m3. Three cases were studied: (i) regular (narrow-band) mechanical waves; (ii) irregular (wide-band) mechanical waves; and (iii) wind waves.

The measured surface-drift currents induced by mechanical waves, Ud, are compared with the Stokes drift at the surface, USt, estimated by the well-known formula with the integral over a wave spectrum. In this case, it was found that ratio Ud / USt is varying in the range 0.5 – 0.93 and slightly growing with the decrease of wave steepness, having no visible dependence on the breaking intensity. These estimations are used to separate the wind-induced drift current, Udw, from the total drift at the presence of wind.

In the case of wind waves, the wind-induced part of the surface drift, Udw, is compared with the friction velocity, u*. In our measurements, the ratio Udw / u* varies systematically in the range 0.65 – 1.2. Taking into account the percentage of wave breaking, Br, the wave age, A, and the wave steepness, Ϭ = akp, it was found the parameterization:  Udw = (Br + Ϭ A) u*, which corresponds to the observations with the mean error less than 10%. For the first time, this ratio provides the dependence of the surface wind drift on the surface wave parameters.

How to cite: Polnikov, V. and Ma, H.: Empirical Parameterization of the Wind-induced Drift Currents , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5400, https://doi.org/10.5194/egusphere-egu2020-5400, 2020

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