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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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Brandon G. Reichl, Dong Wang, Tetsu Hara, Isaac Ginis, and Tobias Kukulka

is typically larger and is determined by the mixed layer depth and/or the Stokes drift e -folding depth ( Harcourt and D’Asaro 2008 ; Grant and Belcher 2009 ; Sullivan et al. 2012 ). First observed by Langmuir ( Langmuir 1938 ), it took several decades for the mechanism that drives Langmuir circulations to be identified. This is the Craik–Leibovich (CL) vortex force, which results from interaction between the Stokes drift of surface waves and the upper-ocean Eulerian current vorticity ( Craik

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David E. Amstutz and William B. Samuels

variance withthose of the other investigators because Weber ignoresthe contribution of Langmuir circulation to the totalwind-induced surface drift. The role of Langmuir circulation is summarized in the recent work by Leibovich(1983) and a treatment of the combined effects of Ekman, Stokes and Langmuir circulations is found inHuang (1979). A review of the numerous studies ofwind and wave induced drift by Huang (1979) revealsthe poor state of our present knowledge, despite thefact that these studies have

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Brandon G. Reichl, Isaac Ginis, Tetsu Hara, Biju Thomas, Tobias Kukulka, and Dong Wang

commonly used in ocean circulation models perform relative to an explicit scheme? As discussed earlier, the mean Langmuir turbulence impacts can be included in an implicit manner by tuning the critical Richardson number used in the KPP [KPP-iLT, see section 2a(1) ]. The computational requirements of a surface wave model are not nominal, so the explicit Langmuir turbulence scheme is more costly to employ. Therefore, we aim to determine whether the explicit scheme improves the hurricane upper

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Alan L. M. Grant and Stephen E. Belcher

1. Introduction Foam and other buoyant materials on the surface of the ocean often form lines that are almost parallel to the direction of the wind. Langmuir (1938) showed that these lines form along the convergence zones between counter-rotating vortices in the underlying water. The circulations are now generally believed to form through an instability arising from the interaction of the Stokes drift, induced by the surface waves, and the shear in the current ( Craik and Leibovich 1976

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Peter E. Hamlington, Luke P. Van Roekel, Baylor Fox-Kemper, Keith Julien, and Gregory P. Chini

, A. D. D. , 1977 : Generation of Langmuir circulations by an instability mechanism . J. Fluid Mech. , 81 , 209 – 223 , doi: 10.1017/S0022112077001980 . Craik , A. D. D. , and S. Leibovich , 1976 : A rational model for Langmuir circulations . J. Fluid Mech. , 73 , 401 – 426 , doi: 10.1017/S0022112076001420 . D’Asaro , E. , and G. Dairiki , 1997 : Turbulence intensity measurements in a wind-driven mixed layer . J. Phys. Oceanogr. , 27 , 2009 – 2022 , doi: 10

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Ramsey R. Harcourt

wall-bounded layers (e.g., Weller et al. 1985 ; Zedel and Farmer 1991 ; Thorpe et al. 1994 ). The latter three features are associated by the field studies (obs 3–5) with the surface streak and downwelling signatures of Langmuir circulations ( Langmuir 1938 ), upper-ocean structures composed of counterrotating surface vortex pairs below surface convergence zones, aligned to the wind and waves. Interactions between the surface waves’ Stokes drift and the wave phase–averaged Eulerian momentum

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Tobias Kukulka, Kara L. Law, and Giora Proskurowski

simulations of microplastic marine debris . J. Geophys. Res. Oceans , 120 , 7559–7573 , doi: 10.1002/2015JC010840 . Colbo , K. , and M. Li , 1999 : Parameterizing particle dispersion in Langmuir circulation. J. Geophys. Res. , 104 , 26 059–26 068 , doi: 10.1029/1999JC900190 . Cozar , A. , and Coauthors , 2014 : Plastic debris in the open ocean . Proc. Natl. Acad. Sci. USA , 111 , 10 239 – 10 244 , doi: 10.1073/pnas.1314705111 . D’Asaro , E. , 2000 : Simple suggestions for

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Wallace E. Howell

VOL. 17, NO. 12 JO'URNAL OF APPLIED METEOROLOGY DECEMBER 1978Night Versus Day Cloud Seeding in Langmuir's Periodic Experiment WALLACE E. HOWELLOffce of Atmospheric Resources Management, Division of Research, Bureau of Reclamation, U.S. Department of the Interior, Denver, CO 80225 (Manuscript received 8 December 1977, in final form 10 June 1978)ABSTRACT During the last ten 28-day cycles of

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Brodie C. Pearson, Alan L. M. Grant, Jeff A. Polton, and Stephen E. Belcher

stratification. The K-profile parameterization (KPP) model ( Large et al. 1994 ) and the Price–Weller–Pinkel (PWP) model ( Price et al. 1986 ), which are both popular OSBL models, produced stratification similar to the LES without Langmuir turbulence. Plueddemann and Weller (1999) showed that Langmuir circulations, which are structures associated with the presence of Langmuir turbulence, were present over the observation period simulated by Kukulka et al. (2013) . They also showed that in periods of weak

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