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Yign Noh and Yeonju Choi

in Noh et al. (2004 , 2009 ) and Goh and Noh (2013) , in which both Langmuir circulation and wave breaking are realized. The wavelength and height for U S were fixed as 40 and 1 m, and was fixed as = 0.01 m s −1 , resulting in La = 0.45. The simulation was carried out to reproduce the formation of a diurnal thermocline under constant and Q 0 , starting either from the homogeneous mixed layer with uniform density and from the stratified layer with a preexisting thermocline. Integration

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Conrad L. Ziegler, Peter S. Ray, and Donald R. MacGorman

2098 JOURNAL OF THE ATMOSPHERIC SCIENCES VOL. 43, No. 19Relations of Kinematics,Microphysics and Electrificationin an Isolated Mountain ThunderstormCONRAD L. ZIEGLER, PETER s. RAY,* AND DONALD R. MAORMAN National Severe Storms Laboralory, NOAA, Norman. OK 73069 (Manuscript received 26 August 1985, in final form 7 April 1986)ABSTRACTThis paper ad- aspects of the airflow, microphysics, and electrification in a mountain thunderstormwhich occurred on 7 August 1979 over the Langmuir

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reports did notgive a complete enough picture, so that in the annals ofment of the Army, Washington 25, D. C.I Present affiliation: Diamond Ordnance Fuze Laboratories, Ordnancc Corps, Depart-"-..*.. ..... . .. . . . . ..-I-.-... +-::* .......,~80'+IS*75' 70'8FIGURE 1.-Solid track is the path of the hurricane of October10-16,1947, as presented by Langmuir [l]. Note the dashedcircle outlining the "approximate area of the clouds of the hurri-cane" at the time of seeding (1138-1208 E S T ). (This figure

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S. A. Thorpe and A. J. Hall

survey atthe position of the displaced band in Fig. 4. The separation and persistence of the banded targets(DD, Fig. 2) seen in the 90-kHz records are consistentwith their being caused by Langmuir circulation, creating bands of sound-scattering bubble clouds roughlyparallel to the wind direction (see Thorpe 1984; Zedeland ?armer 1991 ). A further example is shown in Fig.5. The persistence time of 5-10 min in the alongshorecurrent of 13 cm s-~ in Fig. 2 (or 36 cm s-~ measuredby the 80-kHz sonar at

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Lachlan Stoney, Kevin J. E. Walsh, Steven Thomas, Paul Spence, and Alexander V. Babanin

the upper ocean when momentum is transferred to the subsurface through wave breaking and Langmuir circulation. Wave breaking, however, only injects turbulence at the scale of wave height (meters) and then relies on vertical diffusion of the turbulence, while Langmuir circulation provides vertical advection of the turbulence at the rate of cm s −1 —both the diffusion and advection are much slower than the turbulence vortex turnover and hence the lifetime (e.g., Babanin et al. 2009 ). In the

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S. A. Thorpe and T. R. Osborn

et al. 2002 ) produced by breaking waves. No evidence has been found that below the Langmuir circulation convergence regions, commonly marked on the water surface by windrows, ramps are more or less common than elsewhere in spite of the expectation that the downwind flow, and cross-wind component of vorticity, may be greater in such regions ( Thorpe 2004 ), favoring shear instability with billow and braid formation. Any connection between the two phenomena, temperature ramps and Langmuir

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Yign Noh, Gahyun Goh, and Siegfried Raasch

analyzing the LES data. Especially we focused on the role of wind forcing during the deepening of the convective mixed layer and its dependence on latitude. 2. Simulation The LES model used in the present simulation is the same as used in Noh et al. (2004 ; 2009) in which Langmuir circulation (LC) is realized by the Craik–Leibovich vortex force ( Craik and Leibovich 1976 ) and wave breaking is represented by stochastic forcing. The model domain is 300 m in both horizontal directions and 80 m in the

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Ian Eames

processes, such as Langmuir circulation cells ( Leibovich 1983 ), are also important in redistributing heat and matter throughout the upper layer of the ocean ( Thorpe 1984 ). Stokes drift—a second-order drift velocity of fluid particles in the direction of wave propagation—is a major component of wave-induced transport. Stokes (1847) originally examined the transport of fluid particles by water waves propagating over an infinitely deep body of fluid, and he demonstrated that they execute circular

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James C. McWilliams and Juan M. Restrepo

in a sometimes dramatic way (e.g., Longuet-Higgins and Stewart 1960 , 1961 ; Hasselmann 1971 ). It also influences the ocean currents. Hasselmann (1970) shows that the Stokes drift is capable of inducing, through the Coriolis force, both an opposing mean Eulerian current as well as inertial oscillations. Craik and Leibovich (1976, hereafter referred to as CL) show that the interaction of the Stokes drift with the mean flow could give rise to Langmuir circulation cells. Huang (1979

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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

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