On the Influence of Swell Propagation Angle on Surface Drag

Patton, Edward G.; Sullivan, Peter P.; Kosović, Branko; Dudhia, Jimy; Mahrt, L.; Žagar, Mark; Marić, Tomislav

doi:10.1175/jamc-d-18-0211.1

Cited by 28 publications

(54 citation statements)

References 48 publications

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“…This disequilibrium can lead to ocean surface waves having a critical role in the atmosphere‐ocean interaction. For example, momentum fluxes from atmosphere to ocean have been expressed as a function of wave state (Drennan et al., 2003; Janssen, 1991; Patton et al., 2019; Taylor & Yelland, 2001). The upper ocean structure is modified by turbulence in the surface ocean.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Ocean Wave‐Dependent Momentum Flux on Global Ocean Climate

Shimura

Hemer

Lenton

et al. 2020

Geophysical Research Letters

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Accurate knowledge of air-sea fluxes of momentum, heat, and carbon are central to fully understanding the evolution of the climate system. The role of ocean surface waves has been largely overlooked in global climate models despite the growing body of work elucidating the influence of ocean wave state on air-sea fluxes. Here we account for the impact of ocean surface waves on global ocean climate using a global ocean model through implementation of wave-dependent momentum fluxes. Wave-dependent momentum fluxes improve the simulation of observed ocean heat content (OHC) through increasing the trend in OHC over the last three decades. Specifically, the larger increase in OHC is attributable to increased net heat flux in the Southern Hemisphere (SH). These results highlight the important role of accounting for wave-dependent momentum transfer in terms of both simulating future climate and understanding changes over the recent historical period. Plain Language Summary Climate change is one of the main issues of sustainable development. The projection of climate change is important for assessment of impact on our environment, and the global climate model is used for the climate change projection. Accurate knowledge of momentum, heat, and carbon transfer at the atmosphere-ocean interface, so-called air-sea fluxes, is central to fully understanding the evolution of the climate system. Ocean surface waves exist everywhere in the global atmosphere-ocean interface. Many previous studies found that the air-sea fluxes are controlled by ocean surface waves. However, the roles of ocean surface waves are ignored in the global climate model. Here we account for the impact of ocean surface waves on global ocean climate. Ocean wave-dependent fluxes improve the simulation of ocean heat storage through increasing the trend in ocean heat storage over the last three decades to be more in line with observed historical changes. These results highlight the important role of accounting for wave-dependent air-sea fluxes in terms of both simulating future climate and understanding changes over the recent historical period.

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Section: Introductionmentioning

confidence: 99%

Impacts of Ocean Wave‐Dependent Momentum Flux on Global Ocean Climate

Shimura

Hemer

Lenton

et al. 2020

Geophysical Research Letters

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“…This typically leads to a large variability of the measure c d coefficient (see e.g. Csanady, 2001;Oost et al, 2002;Large, 2006;Patton et al, 2019). Results from two sets of numerical experiments, exp1 and exp2, are presented here.…”

Section: The One-dimensional Non-linear Boundary-layer Modelmentioning

confidence: 99%

Jarzynski equality and Crooks relation for local models of air-sea interaction

Wirth¹,

Lemarié²

2020

Preprint

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Abstract. We show using a hierarchy of local models of air-sea interaction that the most prominent of the work theorems, the Jarzynski equality and the Crooks relation can be applied to air-sea interaction. In the more idealized models, with and without a Coriolis force, the variability is provided from a Gaussian white-noise which modifies the shear between the atmosphere and the ocean. The dynamics is Gaussian and the Jarzynski equality and Crooks relation can be obtained analytically solving stochastic differential equations. The more involved model consists of interacting atmospheric and oceanic boundary-layers, where only the dependence on the vertical direction is resolved, the turbulence is modeled through standard turbulent models and the stochasticity comes from a randomized drag coefficient. It is integrated numerically and can give rise to a non-Gaussian dynamics. Also in this case the Jarzynski equality allows for calculating a dynamic-beta βD of the turbulent fluctuations (the equivalent of the thermodynamic-beta β = (kBT)−1 in thermal fluctuations). The Crooks relation gives the βD as a function of the magnitude of the work fluctuations. It is well defined (constant) in the Gaussian models and can show a slight variation in the more involved models. This demonstrates that recent concepts of stochastic thermodynamics used to study micro-systems subject to thermal fluctuations can further the understanding of geophysical fluid dynamics with turbulent fluctuations.

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“…Kudryavtsev and Makin (2004) concluded that cross-wind swells can lead to a deviation in the stress vector from the mean wind direction, which becomes significant with the decrease in wind speed and the increase in swell phase speed based on a numerical model; however, there are no field observations to support this model result. Patton et al (2019) investigated the impact of swell speed and direction on the wind stress through large eddy simulations and field measurements, and concluded that the swell off-wind angle is a significant factor for the large scatter of roughness and proposed a parameterization of roughness with the misaligned angle to improve the predictive ability of the model.…”

Section: Introductionmentioning

confidence: 99%

Directional Characteristic of Wind Stress Vector Under Swell‐Dominated Conditions

et al. 2020

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The wind stress vector over the ocean surface is often misaligned with the wind direction; this misalignment in a swell‐dominated regime is not well investigated. Directional characteristic of the wind stress vector under swell‐dominated conditions is analyzed through direct flux observations taken over the coastal region in the northern South China Sea. Observational Ogive curves demonstrate that an additional velocity component induced by a strong swell at wind speeds below 4 m/s can be captured at a height of 17 m away from the sea surface. Our results show that swell can cause a deviation in the wind stress from the wind direction, and the stress vectors mostly reside between the wind direction and the opposite swell direction under low to moderate wind and strong background swell conditions. Further directional analysis indicates that the deviation in the stress vector from the wind vector is mainly governed by the speeds and directions of the wind and swell. With the increase in the wind speed and inverse wave age, this deviation decreases and becomes less scattered; additionally, it increases with the angle between the wind and swell directions, and a linear relation is proposed at wind speeds greater than 6 m/s.

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On the Influence of Swell Propagation Angle on Surface Drag

Cited by 28 publications

References 48 publications

Impacts of Ocean Wave‐Dependent Momentum Flux on Global Ocean Climate

Impacts of Ocean Wave‐Dependent Momentum Flux on Global Ocean Climate

Jarzynski equality and Crooks relation for local models of air-sea interaction

Directional Characteristic of Wind Stress Vector Under Swell‐Dominated Conditions

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