Open Ocean Momentum Flux Measurements in Moderate to Strong Winds

Large, William G.; Pond, S.

doi:10.1175/1520-0485(1981)011<0324:oomfmi>2.0.co;2

Cited by 2,478 publications

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“…In open-sea conditions (e.g., Smith, 1980;Large and Pond, 1981) the drag coefficient is 10-15% lower than in coastal or shallower situations (e.g., Garratt, 1977;Wu, 1980;Geernaert et al, 1986Geernaert et al, , 1987, and this difference is believed to be due to a difference in typical sea states. A direct relation between wind stress and sea state is of considerable interest from a remote sensing viewpoint: the sea state in turn determines the radar reflectivity and microwave brightness temperature of the surface, which can be monitored globally by satellites.…”

Section: Influence Of Sea State On Wind Stressmentioning

confidence: 96%

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Sea surface wind stress and drag coefficients: The hexos results

Smith

Anderson

Oost

et al. 1992

Boundary-Layer Meteorol

392

262

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Abstract. Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October-November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.

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Section: Influence Of Sea State On Wind Stressmentioning

confidence: 96%

“…The dissipation method has been "calibrated" by comparisons with simultaneous eddy flux data (e.g., Large and Pond, 1981;Fairall and Larsen, 1986;Fairall et al, 1990;Edson et al, 1991). Combining Equations (1) and (2),…”

Section: Inertial-dissipation Estimates Of Wind Stressmentioning

confidence: 99%

Sea surface wind stress and drag coefficients: The hexos results

Smith

Anderson

Oost

et al. 1992

Boundary-Layer Meteorol

392

262

View full text Add to dashboard Cite

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“…The wind drag coefficient, C s , is given by Large and Pond [36] and Powell et al [37]. The bottom boundary layer is typically not well described in ocean models; thus, the no-slip condition at the sea or river bottom is replaced by a balance between the internal Reynolds stress and the bottom frictional stress: …”

Section: Conflicts Of Interestmentioning

confidence: 99%

Modeling the Influence of River Cross-Section Data on a River Stage Using a Two-Dimensional/Three-Dimensional Hydrodynamic Model

Chen

Liu

2017

Water

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A large amount of accurate river cross-section data is indispensable for predicting river stages. However, the measured river cross-section data are usually sparse in the transverse direction at each cross-section as well as in the longitudinal direction along the river channel. This study presents three algorithms to resample the river cross-section data points in both the transverse and longitudinal directions from the original data. A two-dimensional (2D) high-resolution unstructured-grid hydrodynamic model was used to assess the performance of the original and resampled cross-section data on a simulated river stage under low flow and high flow conditions. The simulated river stages are significantly improved using the resampled cross-section data based on the linear interpolation in the tidal river and non-tidal river segments. The resampled cross-section data based on the linear interpolation satisfactorily maintains the topographic and morphological features of the river channel, especially in the meandering river segment. Furthermore, the performance of the 2D and three-dimensional (3D) models on the simulated river stage was also evaluated using the resampled cross-section data. The results indicate that the 2D and 3D models reproduce similar river stages in both tidal and non-tidal river segments under the low flow condition. However, the 2D model overestimates the river stages in both the tidal and non-tidal river segments compared to the 3D model under the high flow condition. The model sensitivity was implemented to investigate the influence of bottom drag coefficient and vertical eddy viscosity on river stage using 2D and 3D models based on the linear interpolation method to resample river bed cross-section. The results reveal that the change of bottom drag coefficient has a minor impact on river stage, but the change of vertical eddy viscosity is insensitive to river stage.

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“…Wind speed and direction measured 19.5 m above mean sea level at the end of the nearby FRF pier were used to estimate wind stress using the algorithm of Large and Pond (1981). No corrections were made for the likely significant effect of waves and white capping on the wind stress.…”

Section: Observationsmentioning

confidence: 99%

Direct Estimation of the Reynolds Stress Vertical Structure in the Nearshore

Feddersen

Williams

2007

Journal of Atmospheric and Oceanic Technology

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Measurements of the vertical Reynolds stress components in the wave-dominated nearshore are required to diagnose momentum and turbulence dynamics. Removing wave bias from Reynolds stress estimates is critical to a successful diagnosis. Here two existing Reynolds stress estimation methods (those of Trowbridge, and Shaw and Trowbridge) for wave-dominated environments and an extended method (FW) that is a combination of the two are tested with a vertical array of three current meters deployed in 3.2-m water depth off an ocean beach. During the 175-h-long experiment the instruments were seaward of the surfzone and the alongshore current was wind driven. Intercomparison of Reynolds stress methods reveals that the Trowbridge method is wave bias dominated. Tests of the integrated cospectra are used to reject bad Reynolds stress estimates, and the Shaw and Trowbridge estimates are rejected more often than FW estimates. With the FW method, wave bias remains apparent in the cross-shore component of the Reynolds stress. However, the alongshore component of Reynolds stress measured at the three current meters are related to each other with a vertically uniform first EOF containing 73% of the variance, indicating the presence of a constant stress layer. This is the first time the vertical structure of Reynolds stress has been measured in a wave-dominated environment. The Reynolds stress is, albeit weakly, related to the wind stress and a parameterized bottom stress. Using derived wave bias and bottom stress parameterizations, the effect of wave bias on Reynolds stress estimates is shown to be weaker for more typical surfzone conditions (with both stronger waves and currents than those observed here).

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Open Ocean Momentum Flux Measurements in Moderate to Strong Winds

Cited by 2,478 publications

References 0 publications

Sea surface wind stress and drag coefficients: The hexos results

Sea surface wind stress and drag coefficients: The hexos results

Modeling the Influence of River Cross-Section Data on a River Stage Using a Two-Dimensional/Three-Dimensional Hydrodynamic Model

Direct Estimation of the Reynolds Stress Vertical Structure in the Nearshore

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