Sea surface wind stress and drag coefficients: The hexos results

Smith, Stuart D.; Anderson, R.J.; Oost, W.A.; Kraan, C.; Maat, N.; Cosmo, Janice De; Katsaros, Kristina B.; Davidson, Kenneth L.; Bumke, Karl; Hasse, Lutz; Chadwick, Helen M.

doi:10.1007/bf00122064

Cited by 395 publications

(289 citation statements)

References 47 publications

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“…The coefficients proposed by Taylor and Yelland [68] yielded implausibly high z 0 when applied to steep young waves originated by a storm over the central Mediterranean Sea and by strong Mistral blowing off-shore of southern France, corresponding to 2.85% of our observations. These extreme z 0 led to absurdly high u * and k w , and thus we imposed a maximum roughness length of 0.01 m. This value roughly matches the maximum expected from the application of alternative formulations for the estimation of z 0 from the wave field [70][71][72][73][74].…”

Section: Transfer Velocitysupporting

confidence: 51%

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

et al. 2018

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Accurate estimates of the atmosphere-ocean fluxes of greenhouse gases and dimethyl sulphide (DMS) have great importance in climate change models. A significant part of these fluxes occur at the coastal ocean which, although much smaller than the open ocean, have more heterogeneous conditions. Hence, Earth System Modelling (ESM) requires representing the oceans at finer resolutions which, in turn, requires better descriptions of the chemical, physical and biological processes. The standard formulations for the solubilities and gas transfer velocities across air-water surfaces are 36 and 24 years old, and new alternatives have emerged. We have developed a framework combining the related geophysical processes and choosing from alternative formulations with different degrees of complexity. The framework was tested with fine resolution data from the European coastal ocean. Although the benchmark and alternative solubility formulations generally agreed well, their minor divergences yielded differences of up to 5.8% for CH 4 dissolved at the ocean surface. The transfer velocities differ strongly (often more than 100%), a consequence of the benchmark empirical wind-based formulation disregarding significant factors that were included in the alternatives. We conclude that ESM requires more comprehensive simulations of atmosphere-ocean interactions, and that further calibration and validation is needed for the formulations to be able to reproduce it. We propose this framework as a basis to update with formulations for processes specific to the air-water boundary, such as the presence of surfactants, rain, the hydration reaction or biological activity.

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Section: Transfer Velocitysupporting

confidence: 51%

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

et al. 2018

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“…In WAM the Charnock parameter a c is modified to include waveinduced stress and passed back to the atmospheric model. Moreover, to estimate ac, they implemented not only the Janssen [1989,1991] wave-induced wind stress (WS) mechanism but also the wave age (WA) parameterization for roughness Zo derived by Smith et al [1992] during the HEXOS campaign in the North Sea. Overall, the WA and WS results were similar, for surface variables such as U•o, or significant wave height H s. Relative to the uncoupled simulations, Desjardins et al [2000] and Lalbeharry et al [2000] found that the presence of younger rougher seas in coupled simulations can give a -10% reduction in U•o, particularly near the storm peak.…”

Section: Desjardins Et Al [2000] and Lalbeharry Et Al [2000] Selectedmentioning

confidence: 99%

A regional climate model coupled to ocean waves: Synoptic to multimonthly simulations

Perrie¹,

Zhang²

2001

J. Geophys. Res.

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Abstract. The NCAR regional climate model RegCM is coupled to the WAM ocean model, using the sea-state-dependent roughness parameterization derived in the HEXOS experiment. Coupled model simulations are shown to give reduced wind speeds U•0 compared to uncoupled simulations. This is in accord with other recent studies. However, the wave-atmosphere coupling is effected through the friction velocity field u,, rather than through the wind field U•0. Thus because the coupling gives enhanced resistive friction, U•0 is weakened, whereas u, is enhanced. Wave heights, driven by u,, are also increased in our coupled model simulations compared to uncoupled model simulations. Coupled model outputs are shown to compare favorably with air-sea observations collected during the recent Labrador Sea Deep Convection Experiment in 1997, both for synoptic storm timescales and for seasonal timescales. IntroductionExchanges of momentum, heat, and water vapor at the airsea interface have long been recognized as important physical processes for the study of climate dynamics and climate change, occurring on different timescales. Better representations of these fluxes are essential for climate modeling on all timescales. This is particularly true with regard to coupled atmosphere-ocean climate models, whether implemented regionally or globally. In the case of coupled atmosphere-ocean general circulation models (GCMs) it is often necessary to [1998] used coarser grids of 60 and 120 km, which resulted in reduced sensitivity to cyclone intensity and surface fluxes. Moreover, while they found that atmosphere-wave coupling gives small effects on storm development and atmospheric circulation, the impact on surface variables was notable. Relative to uncoupled simulations, they found a slight weakening of the central pressure depression, as well as reduced wave heights and surface wind speeds, with increased momentum flux.

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“…The first level of drag coefficient is the constant value. Going more in details, the sea surface drag coefficient is a function of wind speed, wave state, and atmospheric stability (Monin and Obukhov 1954;Charnock 1955;Large and Pond 1981;Smith et al 1992). However, the parameterizations employed for this coefficient are often only wind-dependent in ocean modeling.…”

Section: Sea Surface Drag Formulations and Comparisonmentioning

confidence: 99%

Atmospheric storm surge modeling methodology along the French (Atlantic and English Channel) coast

et al. 2014

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Storm surge modeling and forecast are the key issues for coastal risk early warning systems. As a general objective, this study aims at improving high-frequency storm surge variations modeling within the PREVIMER system (www.previmer.org), along the French Atlantic and English Channel coasts. The paper focuses on (1) sea surface drag parameterization and (2) uncertainties induced by the meteorological data quality. The modeling is based on the shallowwater version of the model for applications at regional scale (MARS), with a 2-km spatial resolution. The model computes together tide and surge, allowing properly taking into account tide-surge interactions. To select the most appropriate parameterization for the study area, a sensitivity analysis on sea surface drag parameterizations is done, based on comparisons of modeled storm surges (extracted with a tidal component analysis) with four tidal gauges, during four storm events, and over about 7.5 years, where the observed water level is processed in the same way as the modeling results. The tested drag parameterizations are a constant one, as reported by Moon et al. (J Atmos Sci 61: 2321-2333, 2007, Makin (BoundLayer Meteorol 115: 169-176, 2005), and Charnock (J Roy Meteor Soc 81: 639-640, 1955). Charnock's parameterization, either constant with high value (0.022) or relying on a full statistical description of the sea state, enables to improve storm surges forecast with peak errors 10 cm smaller than those computed with the other drag coefficient formulations. The impact of the meteorological forcing quality is evaluated over January 2012 from the comparison between surges modeled with different meteorological data (ARPEGE, ARPEGE High Resolution and AROME) and observations. For event time scale, storm surge computation is highly improved with ARPEGE High Resolution data. For month time scale, statistics of model accuracy are less sensitive to the choice of meteorological forcing. As a conclusion, the Charnock's parameterization is advised to model storm surges on the French Atlantic and English Channel coasts, whereas the quality requirements regarding meteorological inputs depend on the time scale of interest. Within the PREVIMER system, aiming at forecasting events, ARPEGE High Resolution data are used.

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Sea surface wind stress and drag coefficients: The hexos results

Cited by 395 publications

References 47 publications

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

The FuGas 2.3 Framework for Atmosphere–Ocean Coupling: Comparing Algorithms for the Estimation of Solubilities and Gas Fluxes

A regional climate model coupled to ocean waves: Synoptic to multimonthly simulations

Atmospheric storm surge modeling methodology along the French (Atlantic and English Channel) coast

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