Field investigations of the drift of artificial thin films on the sea surface

Malinovsky, V. V.; Дулов, В. А.; Korinenko, A. E.; Bol’shakov, A. N.; Smolov, V. E.

doi:10.1134/s0001433807010124

Cited by 8 publications

(9 citation statements)

References 12 publications

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“…Because drift velocity at a 5-m depth is not vanishing, the absolute speed of the slick with respect to the lower boundary of the Ekman layer should be larger. However, our experimental estimate of the sea surface wind drift coefficient (identified with slick drift) seems to be smaller than the commonly accepted 3% of the wind speed [an overview of experimental estimates of the surface wind drift coefficient showing their scattering from 1%-7% can be found, e.g., in Malinovsky et al (2007)]. …”

Section: A Driftersmentioning

confidence: 71%

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On the Vertical Structure of Wind-Driven Sea Currents

Kudryavtsev

Shrira

Дулов

et al. 2008

Journal of Physical Oceanography

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The vertical structure of wind-driven sea surface currents and the role of wind-wave breaking in its formation are investigated by means of both field experiments and modeling. Analysis of drifter measurements of surface currents in the uppermost 5-m layer at wind speeds from 3 to 15 m s Ϫ1 is the experimental starting point of this study. The velocity gradients beneath the surface are found to be 2 to 5 times weaker than in the "wall" boundary layer. Surface wind drift (identified via drift of an artificial slick) with respect to 0.5-m depths is about 0.7%, which is even less than the velocity defect over the molecular sublayer in the wall boundary layer at a smooth surface. To interpret the data, a semiempirical model describing the effect of wave breaking on wind-driven surface currents and subsurface turbulence is proposed. The model elaborates on the idea of direct injection of momentum and energy from wave breaking (including microscale breaking) into the water body. Momentum and energy transported by breaking waves into the water significantly enhance the turbulent mixing and considerably decrease velocity shears as compared to the wall boundary layer. No "artificial" surface roughness scale is needed in the model. From the experimental fact of the existence of cool temperature skin at the sea surface, it is deduced that there is a molecular sublayer at the water side of the sea surface with a thickness that depends on turbulence intensity just beneath the surface. The model predictions are consistent with the reported and other available experimental data.

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Section: A Driftersmentioning

confidence: 71%

“…1A. Evolution of the geometric properties of the slick (such as its area and configuration parameters) is reported in Malinovsky et al (2007). In the present study, we shall use only its mean drift velocity defined through the coordinates of its "center of mass."…”

Section: Discussionmentioning

confidence: 99%

On the Vertical Structure of Wind-Driven Sea Currents

Kudryavtsev

Shrira

Дулов

et al. 2008

Journal of Physical Oceanography

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“…To validate the KaDOP model, Equation 14, it was first applied to the data subset with known wind and wave conditions, but unknown surface currents (Figure 7, left three columns). As a proxy for 10-m current shear, 1.5%U was used that was half of the "classical" 3%U but close to 1.3%U dependence observed at the platform site [56]. In order to emphasize the importance of angular spreading of wave spectrum on DC, we performed simulations with both, 2D and 1D wave spectra obtained from wave gauge measurements.…”

Section: Model Validationmentioning

confidence: 99%

Sea Surface Ka-Band Doppler Measurements: Analysis and Model Development

et al. 2019

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Multi-year field measurements of sea surface Ka-band dual-co-polarized (vertical transmit–receive polarization (VV) and horizontal transmit–receive polarization (HH)) radar Doppler characteristics from an oceanographic platform in the Black Sea are presented. The Doppler centroid (DC) estimated using the first moment of 5 min averaged spectrum, corrected for measured sea surface current, ranges between 0 and ≈1 m/s for incidence angles increasing from 0 to 70 ∘ . Besides the known wind-to-radar azimuth dependence, the DC can also depend on wind-to-dominant wave direction. For co-aligned wind and waves, a negative crosswind DC residual is found, ≈−0.1 m/s, at ≈20 ∘ incidence angle, becoming negligible at ≈ 60 ∘ , and raising to, ≈+0.5 m/s, at 70 ∘ . For our observations, with a rather constant dominant wave length, the DC is almost wind independent. Yet, results confirm that, besides surface currents, the DC encodes an expected wave-induced contribution. To help the interpretation, a two-scale model (KaDOP) is proposed to fit the observed DC, based on the radar modulation transfer function (MTF) previously developed for the same data set. Assuming universal spectral shape of energy containing sea surface waves, the wave-induced DC contribution is then expressed as a function of MTF, significant wave height, and wave peak frequency. The resulting KaDOP agrees well with independent DC data, except for swell-dominated cases. The swell impact is estimated using the KaDOP with a modified empirical MTF.

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“…Despite the evident simplicity of surface drift current measurements, accurate measurements of a wavy water surface can have many sources of error. Field measurements (e.g., Churchill and Csanady 1983;Babanin 1988;Malinovsky et al 2007;Kudryavtsev et al 2008) are influenced by the nonstationarity of the wind field, uncontrolled background currents U b , the stratification of air and water in situ, numerous technical difficulties in field measurements, and other factors. In laboratory (tank) measurements (Toba 1973;Wu 1975;Tsahalis 1979;Longo 2012;Longo et al 2012;Paprota et al 2016;Zavadsky and Shemer 2017), the sources of errors include the influence of the upper and lateral boundaries of the tank, presence of return currents, short wind and wave fetches, and difficulty of placing equipment in a tank.…”

Section: A Initial Informationmentioning

confidence: 99%

Surface Drift Currents Induced by Waves and Wind in a Large Tank

Polnikov

2020

Journal of Physical Oceanography

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The empirical features of surface drift currents induced by both mechanical and wind waves are presented. The measurements were made by using surface floats in a large tank with 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 a well-known formula with an integral over the wave spectrum. In this case, the ratio Ud/USt varies in the range of 0.5–0.93 and slightly increases with decreasing wave steepness. No visible dependence on the breaking intensity is observed. 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 of 0.65–1.2. Considering the percentage of wave breaking, Br, the wave age, A, and the wave steepness, Ϭ, the parameterization of Udw was obtained in the form Udw = (Br + Ϭ A) u*, which corresponds to the observations with a mean error of 10%. For the first time, this ratio provides the dependence of wind-induced drift on the surface wave parameters. The obtained results and problems related to measuring surface drift currents are discussed.

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Field investigations of the drift of artificial thin films on the sea surface

Cited by 8 publications

References 12 publications

On the Vertical Structure of Wind-Driven Sea Currents

On the Vertical Structure of Wind-Driven Sea Currents

Sea Surface Ka-Band Doppler Measurements: Analysis and Model Development

Surface Drift Currents Induced by Waves and Wind in a Large Tank

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