A regime diagram for classifying turbulent large eddies in the upper ocean

Li, Ming; Garrett, Chris; Skyllingstad, Eric D.

doi:10.1016/j.dsr.2004.09.004

Cited by 144 publications

(254 citation statements)

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“…the Stokes drift, and the surface shear current, leads to the generation of Langmuir circulations, causing significant mixing of the water column (Skyllingstad and Denbo 1995;McWilliams et al 1997;Noh et al 2005;Li et al 2005;Harcourt and D'Asaro 2008; Grant and E 2009;Veron et al 2009;Kukulka et al 2010;Belcher et al 2012;D'Asaro 2014). When surface waves break, the turbulence injected into the water column also significantly enhances surface mixing Melville et al 1998;Veron and Melville 1999;Melville et al 2002;Thorpe et al 2003;Gemmrich and Farmer 2004) and leads to substantial deviations from the classical theories (Agrawal et al 1992;Thorpe 1993;Melville 1994;Anis and Moum 1995;Melville 1996;Terray et al 1996; Veron and Melville 2001) and causes significant energy dissipation (Banner et al 2014;Thomson et al 2016;Schwendeman et al 2014;Zappa et al 2016; Melville 2013, 2015).…”

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confidence: 99%

Airflow measurements at a wavy air–water interface using PIV and LIF

Buckley

Véron

2017

Exp Fluids

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geophysical sphere, which largely motivates this study, fluxes of momentum and scalars across the wavy air-sea interface provide boundary conditions for both the atmosphere and the oceans and are therefore, pivotal in controlling the evolution of weather and climate. These fluxes are affected by fine-scale, coupled dynamics above and below the wavy ocean surface. In fact, the surface waves significantly modify the boundary layers on both sides of the interface and it is now well established that it is through waverelated dynamical processes that the air and water boundary layers are coupled (see Sullivan and McWilliams (2010) for a review on the topic).On the water side, for example, it has been shown that the interaction between the wave-induced Lagrangian mass transport, i.e. the Stokes drift, and the surface shear current, leads to the generation of Langmuir circulations, causing significant mixing of the water column (Skyllingstad and Denbo 1995;McWilliams et al. 1997;Noh et al. 2005;Li et al. 2005;Harcourt and D'Asaro 2008; Grant and E 2009;Veron et al. 2009;Kukulka et al. 2010;Belcher et al. 2012;D'Asaro 2014). When surface waves break, the turbulence injected into the water column also significantly enhances surface mixing Melville et al. 1998;Veron and Melville 1999;Melville et al. 2002;Thorpe et al. 2003;Gemmrich and Farmer 2004) and leads to substantial deviations from the classical theories (Agrawal et al. 1992;Thorpe 1993;Melville 1994;Anis and Moum 1995;Melville 1996;Terray et al. 1996; Veron and Melville 2001) and causes significant energy dissipation (Banner et al. 2014;Thomson et al. 2016;Schwendeman et al. 2014;Zappa et al. 2016; Melville 2013, 2015).On the air side, it is clear that surface wave processes also play an important role in the kinematics and dynamics of the boundary layer (e.g. Janssen 1989; Komen et al. 1994;Belcher and Hunt 1998;Hristov et al. 1998; Abstract Physical phenomena at an air-water interface are of interest in a variety of flows with both industrial and natural/environmental applications. In this paper, we present novel experimental techniques incorporating a multi-camera multi-laser instrumentation in a combined particle image velocimetry and laser-induced fluorescence system. The system yields accurate surface detection thus enabling velocity measurements to be performed very close to the interface. In the application presented here, we show results from a laboratory study of the turbulent airflow over wind driven surface waves. Accurate detection of the wavy air-water interface further yields a curvilinear coordinate system that grants practical and easy implementation of ensemble and phase averaging routines. In turn, these averaging techniques allow for the separation of mean, surface wave coherent, and turbulent velocity fields. In this paper, we describe the instrumentation and techniques and show several data products obtained on the air-side of a wavy air-water interface.

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Airflow measurements at a wavy air–water interface using PIV and LIF

Buckley

Véron

2017

Exp Fluids

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“…1 demonstrate that the growth of the wave field substantially reinvigorates Langmuir turbulence in the ocean mixed layer. Following Li et al (2005), we calculate three components of turbulence intensities averaged over the mixed layer. Their magnitudes indicate the strength of turbulence eddies while the ordering of the turbulence intensities serve to distinguish the characteristics of these eddies.…”

Section: Resultsmentioning

confidence: 99%

“…2a, the increase in wave height caused the vertical and crosswind turbulence intensities to double, increasing from 2 to 4 m 2 s -2 . In the regime diagram of Li et al (2005), a doubling of wave height causes a 50% reduction in turbulent Langmuir number, thus pushing the turbulence further into the wave-dominated Langmuir turbulence regime. It is interesting but not surprisingly to note that the turbulence intensity in the downwind direction stayed almost flat.…”

Section: Resultsmentioning

confidence: 99%

Oceanic LES Simulations to Interpret and Synthesize Turbulence Measurements Obtained During CBLAST-Low

Li¹

2006

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LONG-TERM GOALSTo understand the effects of upper-ocean turbulent processes on air-sea interaction and obtain improved parameterization of these processes for use in coastal and large-scale ocean models. OBJECTIVESThis proposal has two primary objectives: (1) to improve understanding of air-sea interaction in fetchlimited shallow seas; (2) interpret observational data collected during CBLAST-Low. APPROACHBecause of limited wind fetch and shallow water depth, air-sea interaction in coastal oceans is very different from that in the open ocean. Surface waves in coastal oceans often have a sea state far from the fully-developed sea. As shown in recent observations (Donelan et al., 1993;Garrett, 1997), drag coefficient is a strong function of wave age. At the same wind speed, the air-sea momentum flux in growing seas may be significantly larger than that in fully-developed seas. Wave spectrum in growing seas is narrowly peaked so that the Stokes drift current is different. These differences in wind stress and wave field can cause dramatic changes in turbulence characteristics in the ocean surface layer. The Air-Sea Interaction Tower (ASIT) constructed during the CBLAST program provides an ideal platform to observe and monitor air-sea interaction processes in the coastal ocean. Our modeling work is intended to facilitate the interpretations of the CBLAST measurements and improve our understanding of air-sea interaction in fetch-limited shallow seas.Surface forcing conditions during CBLAST-Low experiment varied from negligible wind stress and strong thermal forcing to medium wind speeds where wave breaking and Langmuir circulations are expected to play a role in air-sea exchange processes (Plueddemann, 2004). The majority of winds were from the SW quadrant at 3-7 m/s, whereas the weakest winds were from the SE. The strongest winds were from the NW, but these events were short lived compared to those from the SW. Varying wind directions relative to Martha's Vineyard create a complex wave field at the observational site, which may include growing, short-fetch wind waves and decaying wind waves along with persistent swell from the south. To interpret the observational data collected under these complex wind and wave conditions, we have identified a few "key" scenarios/events and conducted simulation studies using the LES model. They include (1) steady wind and growing/decaying waves; (2) steady wind and swells; 1

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“…Sullivan and McWilliams (2010) summarise several studies focusing on the Langmuir mechanism and it is clear that Langmuir circulation (or Langmuir turbulence) greatly enhances turbulent vertical fluxes of momentum and heat at the surface. A regime diagram for classifying turbulent large eddies in the upper ocean was suggested by Li et al (2005) using the Hoennecker number (Li and Garrett 1995) as a dimensionless number comparing the unstable buoyancy force driving thermal convection with the wave forcing driving the Langmuir circulation. According to Li et al (2005), the wind driven upper ocean is dominated by Langmuir turbulence under typical sea state conditions.…”

Section: Large-scale Turbulencementioning

confidence: 99%

“…A regime diagram for classifying turbulent large eddies in the upper ocean was suggested by Li et al (2005) using the Hoennecker number (Li and Garrett 1995) as a dimensionless number comparing the unstable buoyancy force driving thermal convection with the wave forcing driving the Langmuir circulation. According to Li et al (2005), the wind driven upper ocean is dominated by Langmuir turbulence under typical sea state conditions. Transition from Langmuir to convective turbulence occurs with strong thermal convection, relatively low winds and small surface velocity.…”

Section: Large-scale Turbulencementioning

confidence: 99%

Transfer Across the Air-Sea Interface

Garbe

Rutgersson

Boutin

et al. 2013

Springer Earth System Sciences

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The efficiency of transfer of gases and particles across the air-sea interface is controlled by several physical, biological and chemical processes in the atmosphere and water which are described here (including waves, large-and small-scale turbulence, bubbles, sea spray, rain and surface films). For a deeper understanding of relevant transport mechanisms, several models have been developed, ranging from conceptual models to numerical models. Most frequently the transfer is described by various functional dependencies of the wind speed, but more detailed descriptions need additional information. The study of gas transfer mechanisms uses a variety of experimental methods ranging from laboratory studies to carbon budgets, mass balance methods, micrometeorological techniques and thermographic techniques. Different methods resolve the transfer at different scales of time and space; this is important to take into account when comparing different results. Air-sea transfer is relevant in a wide range of applications, for example, local and regional fluxes, global models, remote sensing and computations of global inventories. The sensitivity of global models to the description of transfer velocity is limited; it is however likely that the formulations are more important when the resolution increases and other processes in models are improved. For global flux estimates using inventories or remote sensing products the accuracy of the transfer formulation as well as the accuracy of the wind field is crucial. IntroductionThe transfer of gases and particles across the air-sea interface depends not only on the concentration difference between the water and the air, but also on the efficiency of the transfer process. The efficiency of the transfer is controlled by complex interaction of a variety of processes in the air and in the water near the interface. Here we treat both gases and particles since the transfer, to some extent, is governed by similar mechanisms. Studies of transfer across the air-sea interface include a variety of methods and techniques ranging from laboratory studies, modeling and large-scale field studies. Various methods reach somewhat different conclusions, due to representation of different

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A regime diagram for classifying turbulent large eddies in the upper ocean

Cited by 144 publications

References 21 publications

Airflow measurements at a wavy air–water interface using PIV and LIF

Airflow measurements at a wavy air–water interface using PIV and LIF

Oceanic LES Simulations to Interpret and Synthesize Turbulence Measurements Obtained During CBLAST-Low

Transfer Across the Air-Sea Interface

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