Wind stress in the presence of swell under moderate to strong wind conditions

García–Nava, Héctor; Ocampo‐Torres, Francisco J.; Osuna, P.; Donelan, Mark A.

doi:10.1029/2009jc005389

Cited by 53 publications

(43 citation statements)

References 37 publications

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“…An extensive description of the experiment can be found in the paper by Ocampo-Torres et al (2011), while details on data acquisition and processing are given by García-Nava et al (2009).…”

Section: Gulf Ofmentioning

confidence: 99%

“…At low winds the direct interaction of swell with the air flow above causes the C D to increase (Pan et al 2005, García-Nava et al 2009). At high winds there are two other processes at play: the presence of underdeveloped, fetch-limited wind seas causes the surface roughness to increase (Drennan et al 2003) and the presence of swell decreases the wind sea-associated roughness (García-Nava 2009).…”

Section: Drag Coefficientmentioning

confidence: 99%

“…Also notice that the roughness of the steepest waves (darker circles) is lower than that estimated for pure wind seas using the relationship of Drennan et al (2003) (dashed line), while less steep waves seem to be rougher than is expressed by the pure wind sea relationship. The steepest waves correspond to the highest winds in which the reduction of z 0 due to swell is an important process; as wind speed decreases (less steep waves) the reduction in z 0 is smaller and can be overcome by the direct contribution of momentum from swell to the atmosphere (García-Nava et al 2009). The effect of swell on wind sea wave steepness can be observed in Figure 8 as the progressive decreasing of Hs ws as a function of l p ws as the importance of swell parameter, z=E s /E ws , increases.…”

Section: Sea State Dependence In High Windsmentioning

confidence: 99%

“…Note that while wave age formula is based on wind sea properties, the parameterization of Taylor and Yelland (2001) uses the full spectrum properties in an attempt to include the effect of mixed seas. It is believed that the direct interaction of swell with the air flow (see Donelan and Dobson 2001) has a great impact on drag estimates from the IntOA experiment in low wind conditions (García-Nava et al 2009). The effect of the direct interaction of swell with the air flow decreases rapidly with increasing wind speed (Pan et al 2005).…”

Section: Sea State Dependence In High Windsmentioning

confidence: 99%

“…Waves were recorded with a pentagonal array of eight wave wires, one wire on each side of the pentagon and three wires at the centre, in which each wire measured the surface height at a single point. Wind velocity and surface height measurements were corrected for buoy motion as described by García-Nava et al (2009). Wind speed was transformed to neutral values as…”

Section: The Gulf Of Tehuantepec Experimentsmentioning

confidence: 99%

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On the parameterization of the drag coefficient in mixed seas

García–Nava¹,

Ocampo‐Torres

Hwang

2012

Sci. Mar.

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SUMMARY: An analysis of the performance of parameterizations for the drag coefficient C D over the ocean is presented. The results were obtained by considering detailed observations from the recent IntOA experiment in which a co-existence of wind sea and swell provides characteristic mixed sea conditions in a wide range of wind speeds. Recent research has advanced our understanding of air-sea fluxes, proposing new functional forms for the drag coefficient, as well as applying wavelength scaling and determining dimensionally consistent expressions for the drag coefficient. Nevertheless, a detailed analysis of the influence of wind sea parameters confirms the need to include the sea state dependence on parameterizing C D for mixed sea conditions. It is also shown that better results are obtained when aerodynamic roughness is considered as a function of wave age and wave steepness, or equivalently if C D is expressed as a function of a characteristic peak frequency defined through the wave momentum spectrum.Keywords: drag coefficient, sea state, swell, mixed seas. RESUMEN: El coEficiEntE dE arrastrE sobrE la supErficiE dEl mar como función dE las caractErísticas dEl olEajE. -Se presenta un análisis del desempeño de algunas parametrizaciones del coeficiente de arrastre C D sobre la superficie del mar. Los resultados se obtienen a partir de observaciones detalladas durante el experimento IntOA. En ese experimento la existencia simultánea de oleaje generado localmente y oleaje que proviene de tormentas lejanas, nos brinda características únicas del estado del mar con constituyentes mixtas de oleaje en una gama amplia de velocidades del viento. A través de investigaciones recientes se ha avanzado en el conocimiento de los flujos entre el océano y la atmósfera, al proponer nuevas formas funcionales del coeficiente de arrastre, así como al utilizar expresiones dimensionalmente consistentes que se basan en escalas asociadas a la longitud de onda de las olas. Los resultados de este trabajo confirman la necesidad de incluir la influencia del estado del mar en las parametrizaciones del coeficiente de arrastre, especialmente bajo condiciones mixtas de oleaje. También se demuestra que se obtienen mejores resultados cuando la escala de rugosidad aerodinámica se considera como una función de la edad de la ola y de la pendiente del oleaje local o de forma equivalente, cuando C D se expresa como función de una frecuencia característica asociada al pico espectral que se determina mediante el espectro del momento del oleaje.Palabras clave: coeficiente de arrastre, estado del mar, swell, oleaje mixto.

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Section: Gulf Ofmentioning

confidence: 99%

Section: Drag Coefficientmentioning

confidence: 99%

Section: Sea State Dependence In High Windsmentioning

confidence: 99%

Section: Sea State Dependence In High Windsmentioning

confidence: 99%

Section: The Gulf Of Tehuantepec Experimentsmentioning

confidence: 99%

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On the parameterization of the drag coefficient in mixed seas

García–Nava¹,

Ocampo‐Torres

Hwang

2012

Sci. Mar.

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Sea state dependence of the wind stress over the ocean under hurricane winds

2014

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[1] The impact of the surface wave field (sea state) on the wind stress over the ocean is investigated with fetch-dependent seas under uniform wind and with complex seas under idealized tropical cyclone winds. Two different approaches are employed to calculate the wind stress and the mean wind profile. The near-peak frequency range of the surface wave field is simulated using the WAVEWATCH III model. The high-frequency part of the surface wave field is empirically determined using a range of different tail levels. The results suggest that the drag coefficient magnitude is very sensitive to the spectral tail level but is not as sensitive to the drag coefficient calculation methods. The drag coefficients at 40 m/s vary from 1310 23 to 4310 23 depending on the saturation level. The misalignment angle between the wind stress vector and the wind vector is sensitive to the stress calculation method used. In particular, if the cross-wind swell is allowed to contribute to the wind stress, it tends to increase the misalignment angle. Our results predict enhanced sea state dependence of the drag coefficient for a fast moving tropical cyclone than for a slow moving storm or for simple fetch-dependent seas. This may be attributed to swell that is significantly misaligned with local wind.Citation: Reichl, B. G., T. Hara, and I. Ginis (2014), Sea state dependence of the wind stress over the ocean under hurricane winds,

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Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere‐wave model

Rutgersson

Larsén³

2016

JGR Oceans

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Over the ocean, the atmospheric turbulence can be significantly affected by swell waves.Change in the atmospheric turbulence affects the wind stress and atmospheric mixing over swell waves. In this study, the influence of swell on atmospheric mixing and wind stress is introduced into an atmospherewave-coupled regional climate model, separately and combined. The swell influence on atmospheric mixing is introduced into the atmospheric mixing length formula by adding a swell-induced contribution to the mixing. The swell influence on the wind stress under wind-following swell, moderate-range wind, and nearneutral and unstable stratification conditions is introduced by changing the roughness length. Five year simulation results indicate that adding the swell influence on atmospheric mixing has limited influence, only slightly increasing the near-surface wind speed; in contrast, adding the swell influence on wind stress reduces the near-surface wind speed. Introducing the wave influence roughness length has a larger influence than does adding the swell influence on mixing. Compared with measurements, adding the swell influence on both atmospheric mixing and wind stress gives the best model performance for the wind speed. The influence varies with wave characteristics for different sea basins. Swell occurs infrequently in the studied area, and one could expect more influence in high-swell-frequency areas (i.e., low-latitude ocean). We conclude that the influence of swell on atmospheric mixing and wind stress should be considered when developing climate models.

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Wind stress in the presence of swell under moderate to strong wind conditions

Cited by 53 publications

References 37 publications

On the parameterization of the drag coefficient in mixed seas

On the parameterization of the drag coefficient in mixed seas

Sea state dependence of the wind stress over the ocean under hurricane winds

Swell impact on wind stress and atmospheric mixing in a regional coupled atmosphere‐wave model

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