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Antony K. Liu, Seelye Martin, and Ronald Kwok

. Lawrence Island polynya. The young ice area of polynya within each SAR image can be estimated and its growth rate is found to be 2.52 exp(day/3.36). b. The active polynya region For the active polynya region on 27 February, Fig. 5 shows the long, linear streaks characteristic of the Langmuir circulation and its 2D FFT. The transformed image in Fig. 5b shows that the Langmuir cells have many scales with one peak at 120 m and another at approximately 230 m. Figure 6 shows the use of this Fourier and

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Jerome A. Smith

1969 ; Longuet-Higgins 1970a , b ); the interaction of freely propagating long and short surface waves ( Longuet-Higgins 1969 ; Hasselmann 1971 ; Garrett and Smith 1976 ; and many others); and the generation of Langmuir circulation (LC), a prominent form of motion in the wind-driven surface mixed layer (e.g., Langmuir 1938 ; Craik 1977 ; Leibovich 1980 ; Li et al. 1995 ; Skyllingstad and Denbo 1995 ; McWilliams et al. 1997 ; McWilliams and Sullivan 2000 ; Phillips 2002 ; Sullivan et al

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Gregory P. Gerbi, John H. Trowbridge, James B. Edson, Albert J. Plueddemann, Eugene A. Terray, and Janet J. Fredericks

for generating turbulence. In the ocean’s surface boundary layer (mixed layer), the physical mechanisms thought to be important in turbulence production include boundary stress, boundary buoyancy flux, wave breaking, and Langmuir circulation. This study was undertaken in conditions conducive to the formation of turbulence by all of these mechanisms, and we hope that it will aid in our understanding of mixed layer turbulence dynamics and in our ability to parameterize such turbulence in closure

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Yign Noh, Gahyun Goh, Siegfried Raasch, and Micha Gryschka

clarify its dynamical process by analysis of LES data. In particular, investigation was focused on how turbulence at the thermocline is modified during the formation of a diurnal thermocline. It was also investigated how the result is affected by Langmuir circulation (LC), WB, radiation penetration, and the diurnal variation of the surface buoyancy flux. 2. Simulation For the simulation, we used the LES model for the ocean mixed layer developed by Noh et al. (2004) , in which both LC and WB are

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Rebecca R. Schudlich and James F. Price

sources including a surface-intensified geostrophic flow coupled to the local wind through Ekman pumping, Langmuir circulation, a logarithmic boundary layer, or a surface-wave induced bias. We cannot quantify Ekman pumping with the LOTUS data and can only give generic estimates of the effects of Langmuir circulations, which we do below. Here we will consider in detail the latter two processes that could produce a downwind shear in the near-surface layer: (i) a logarithmic boundary layer (“wall layer

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S. A. Thorpe

the size distribution. Factors contributingto this discrepancy are discussed. It is possible that bubble populations measured by floating cameras are biasedbecause of the effects of Langmuir circulation both on the float and on the bubbles.1. Introduction Subsurface bubbles formed by breaking wind waveshave been subject to investigation for some time, primarily because of their role in the formation of aerosolswhen the bubbles burst on returning to the surface(Blanchard and Woodcock, 1957

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Jeff A. Polton, David M. Lewis, and Stephen E. Belcher

for Langmuir circulations ( Leibovich 1983 ; McWilliams et al. 1997 ; Teixeira and Belcher 2002 ). The interaction of the Stokes drift with planetary vorticity is the subject of this paper. The effects of Stokes drift in a rotating frame was first considered by Ursell (1950) , Hasselmann (1970) and Pollard (1970) who showed that, for an inviscid ocean, there can be no net mass transport associated with the Stokes drift. Subsequently, also using a Lagrangian description, Weber (1983a) , b

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Fabrice Ardhuin, Louis Marié, Nicolas Rascle, Philippe Forget, and Aron Roland

the Ekman depth is generally on the order of 30 m, it follows that the classical Ekman theory, with a constant eddy viscosity, does not apply here. Instead, this large near-surface deflection is consistent with model results obtained with a high surface mixing—such as those induced by Langmuir circulations ( McWilliams et al. 1997 ; Kantha and Clayson 2004 ), breaking waves ( Craig and Banner 1994 ; Mellor and Blumberg 2004 ; Rascle et al. 2006 ), or both—and consistent with the few observed

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Tomas Chor, James C. McWilliams, and Marcelo Chamecki

Abstract

The K-profile parameterization (KPP) is a common method to model turbulent fluxes in regional and global oceanic models. Many versions of KPP exist in the oceanic sciences community and one of their main differences is how they take the effects of nonbreaking waves into account. Although there is qualitative consensus that nonbreaking waves enhance vertical mixing due to the ensuing Langmuir circulations, there is no consensus on the quantitative aspects and modeling approach. In this paper we use a recently-developed method to estimate both components of KPP (the diffusive term, usually called local, and the nondiffusive component, usually called nonlocal) based on numerically-simulated turbulent fluxes without any a priori assumptions about their scaling or their shape. Through this method we show that the cubic shape usually used in KPP is not optimal for wavy situation and propose new ones. Furthermore we show that the formulation for the nondiffusive fluxes, which currently only depend on the presence of surface buoyancy fluxes, should also take wave effects into account. Finally, we investigate how the application of these changes to KPP improves the representation of turbulent fluxes in a diagnostic approach when compared to previous models.

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James Edson, Timothy Crawford, Jerry Crescenti, Tom Farrar, Nelson Frew, Greg Gerbi, Costas Helmis, Tihomir Hristov, Djamal Khelif, Andrew Jessup, Haf Jonsson, Ming Li, Larry Mahrt, Wade McGillis, Albert Plueddemann, Lian Shen, Eric Skyllingstad, Tim Stanton, Peter Sullivan, Jielun Sun, John Trowbridge, Dean Vickers, Shouping Wang, Qing Wang, Robert Weller, John Wilkin, Albert J. Williams III, D. K. P. Yue, and Chris Zappa

The Office of Naval Research's Coupled Boundary Layers and Air–Sea Transfer (CBLAST) program is being conducted to investigate the processes that couple the marine boundary layers and govern the exchange of heat, mass, and momentum across the air–sea interface. CBLAST-LOW was designed to investigate these processes at the low-wind extreme where the processes are often driven or strongly modulated by buoyant forcing. The focus was on conditions ranging from negligible wind stress, where buoyant forcing dominates, up to wind speeds where wave breaking and Langmuir circulations play a significant role in the exchange processes. The field program provided observations from a suite of platforms deployed in the coastal ocean south of Martha's Vineyard. Highlights from the measurement campaigns include direct measurement of the momentum and heat fluxes on both sides of the air–sea interface using a specially constructed Air–Sea Interaction Tower (ASIT), and quantification of regional oceanic variability over scales of O(1–104 mm) using a mesoscale mooring array, aircraft-borne remote sensors, drifters, and ship surveys. To our knowledge, the former represents the first successful attempt to directly and simultaneously measure the heat and momentum exchange on both sides of the air–sea interface. The latter provided a 3D picture of the oceanic boundary layer during the month-long main experiment. These observations have been combined with numerical models and direct numerical and large-eddy simulations to investigate the processes that couple the atmosphere and ocean under these conditions. For example, the oceanic measurements have been used in the Regional Ocean Modeling System (ROMS) to investigate the 3D evolution of regional ocean thermal stratification. The ultimate goal of these investigations is to incorporate improved parameterizations of these processes in coupled models such as the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS) to improve marine forecasts of wind, waves, and currents.

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