Search Results

You are looking at 141 - 150 of 476 items for :

  • Langmuir circulation x
  • Refine by Access: All Content x
Clear All
Jerome A. Smith

momentum between waves and the mean. For example, earlier papers ( Longuet-Higgins and Stewart 1960 , 1961 ) provided the basis for the description of the generation of group-bound forced long waves, which is relevant to the “Eulerian response” discussed here. Such wave–current interactions are also considered important in generating and maintaining Langmuir circulation (LC), a prominent form of motion found in the wind-driven surface mixed layer ( Langmuir 1938 ; Craik and Leibovich 1976 ; Craik

Full access
Fabrice Ardhuin, Nobuhiro Suzuki, James C. McWilliams, and Hidenori Aiki

consistencies in section 4 . Conclusions and recommendations on future work on wave–current theory follow in section 5 . Finally, it is important to note that there are two types of wave effects: one depends only on wave properties, and the other depends both on wave and current properties. A typical example of the former is the wave setup/setdown effect, and a typical example of the latter are Langmuir circulations. As the former is independent of current properties, it is possible to compute such an

Full access
Anna-Lena Deppenmeier, Rein J. Haarsma, Chiel van Heerwaarden, and Wilco Hazeleger

appearance on the right-hand side: production by wind input at the surface, Langmuir cell contributions, production by shear, destruction by stratification, vertical diffusion, Kolmogorov dissipation, and internal and surface wave breaking. In Eq. (14) , C WI is a parameter for the wind input, | τ | is the wind stress, ω LC is the Langmuir circulation velocity, and H LC is the depth of the Langmuir cell. The Langmuir circulation strength is calculated according to (15) w LC = C LC u s sin ⁡ ( π

Open access
G. T. Csanady

viscosity-like manner. Their time scale is shortcompared with the time scale ~-r of the irrotationalwaves, which in turn is short compared to the advectivetime scale of the Langmuir circulations. These hypotheses are in accord with known characteristics of the near-surface motion and are readilyreconciled with the requirements of the wall layeranalogy discussed earlier. The unfiltered longer wavesmay be supposed nearly irrotational giving rise toStokes drift, while the breaking wavelets

Full access
Peter Sutherland and W. Kendall Melville

also Melville et al. 2002 ). This implies, in the absence of other mechanisms, between 20% and 90% of dissipation by breaking occurs within approximately O (10) cm of the sea surface. This simplistic view is complicated by the advection of near-surface turbulence (from small wave breaking) downward by larger breakers and other vertical transport processes like Langmuir circulations. The LES simulations of Sullivan et al. (2007) included the effects of these processes advecting turbulence, but

Full access
Hidenori Aiki and Richard J. Greatbatch

EM shear flow and the Stokes-drift flow associated with surface waves and is appropriate to describe the maintenance of Langmuir circulations (LCs; Langmuir 1938 ). LCs play an important role in the vertical mixing of the surface mixed layer of the ocean (e.g., Skyllingstad and Denbo 1995 ; Polton and Belcher 2007 ; Kukulka et al. 2010 ). Some prototypes of the vortex force have been derived by Craik and Leibovich (1976 , hereafter CL76 ) using EM vorticity equations and by Garrett (1976

Full access
G. T. Csanady

weak secondary circulation(more or less aligned with the wind direction) on amore pronounced Ekman drift to the right of the wind,which is constant with depth just as the "general"current is. The secondary circulation aligned with thewind would tend to increase diffusion of, say, a dyepatch along wind, thus explaining a well-known observational fact. A very intriguing question is, how the presence orabsence of Langmuir circulations fits into the framework of (17), As shown for example by Gordon

Full access
B. Ozen, S. A. Thorpe, U. Lemmin, and T. R. Osborn

circulation and with the instability of the mean shear flow within the layer, or with thermal convection under conditions of strong heat flux to the atmosphere, are mainly responsible for the vertical transfer of heat from the surface. These processes may be identified by the presence of large-scale coherent structures in the thermal or velocity field, for example, by temperature anomalies and vertical velocities in the case of Langmuir circulation, temperature ramps or microfronts in the case of

Full access
Sean Haney, Baylor Fox-Kemper, Keith Julien, and Adrean Webb

-modified Ekman layer, and how it modifies SI and GI. These topics will be addressed in a forthcoming paper that focuses on the instability mechanisms that depend on viscosity in the mixed layer. Acknowledgments The authors thank Prof. Gregory Chini for insightful discussions of interactions between symmetric instability and Langmuir circulations, Prof. Eric D’Asaro for suggesting that the submesoscale instabilities of the boundary layer including Stokes forces be explored, and Dr. Peter Sullivan for help

Full access
Xuefeng Zhang, Guijun Han, Dong Li, Xinrong Wu, Wei Li, and Peter C. Chu

1. Introduction Observations ( Kitaigorodskii and Lumley 1983 ; Thorpe 1984 ; Anis and Moum 1992 ; Terray et al. 1996 ; Drennan et al. 1996 ; Babanin 2006 ; Kantha et al. 2010 ) show that the dissipation of turbulent kinetic energy (TKE) is enhanced greatly near the sea surface by surface gravity waves under nonbreaking (including nonbreaking wave turbulence and Langmuir turbulence) and breaking waves. The breaking-wave-induced mixing has been broadly implemented into ocean circulation

Full access