Breaking internal wave groups: Mixing and momentum fluxes

Birch, Daniel A.; Sundermeyer, Miles A.

doi:10.1063/1.3638155

Cited by 10 publications

(3 citation statements)

References 43 publications

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“…Internal wave breaking can lead to shear instability and overturning. Surrounding fluid is mixed, energy is converted into potential energy (e.g., Birch and Sundermeyer 2011), scalar quantities are dissipated, and a patch of relatively well mixed fluid is generated (e.g., Alford and Pinkel 2000). Such diapycnal mixing has been observed episodically in time and space (e.g., Gregg et al 1986).…”

Section: Introductionmentioning

confidence: 99%

Vortex Stability in a Large-Scale Internal Wave Shear

Brunner-Suzuki

Sundermeyer

Lelong

2012

Journal of Physical Oceanography

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The effect of a large-scale internal wave on a multipolar compound vortex was simulated numerically using a 3D Boussinesq pseudospectral model. A suite of simulations tested the effect of a background internal wave of various strengths, including a simulation with only a vortex. Without the background wave, the vortex remained apparently stable for many hundreds of inertial periods but then split into two dipoles. With increasing background wave amplitude, and hence shear, dipole splitting occurred earlier and was less symmetric in space. Theoretical considerations suggest that the vortex alone undergoes a self-induced mixed barotropic–baroclinic instability. For a vortex plus background wave, kinetic energy spectra showed that the internal wave supplied energy for the dipole splitting. In this case, it was found that the presence of the wave hastened the time to instability by increasing the initial perturbation to the vortex. Results suggest that the stability and fate of submesoscale vortices in the ocean may be significantly modified by the presence of large-scale internal waves. This could in turn have a significant effect on the exchange of energy between the submesoscale and both larger and smaller scales.

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Section: Introductionmentioning

confidence: 99%

Vortex Stability in a Large-Scale Internal Wave Shear

Brunner-Suzuki

Sundermeyer

Lelong

2012

Journal of Physical Oceanography

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“…The panels show calibrated backscatter (blue wavelength) and fluorescence (green wavelength) lidar returns as a function of time and depth in the water column. Also shown are the results of a preliminary inversion of the dye signal as inferred from each of the two channels using the methods described in Terray and Sundermeyer (2005), and Sundermeyer et al (2007). The result shows clear signal in both channels, although the raw backscatter dye signal is less clear in this depiction, as there is a background exponential decay of signal with depth.…”

Section: Latmix 2011mentioning

confidence: 99%

LIDAR and Numerical Modeling Studies of Small-Scale Lateral Dispersion in the Ocean

Sundermeyer¹

2012

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LONG-TERM GOALSOur long-term goal is to better understand lateral mixing processes in the ocean on scales of 10 m to 10 km, i.e., the "submesoscale". We aim to understand the underlying mechanisms and forcing, as well as the temporal, spatial, and scale variability of such mixing. This research will contribute to fundamental knowledge of ocean dynamics at these scales, and to efforts to properly parameterize sub-grid scale mixing and stirring in numerical models. Ultimately our research will also enhance modeling and understanding of upper ocean ecosystems, since the flow of nutrients and plankton depends on stirring and mixing at these scales. OBJECTIVESOne objective of our work is to determine the extent to which shear dispersion -the interaction of vertical mixing with vertical shear -can explain lateral dispersion at scales of 10 m to 10 km. A second objective is to determine whether slow but persistent vortices enhance the stirring attributable to shear dispersion. We also share the overall objectives of the Lateral Mixing DRI to try to determine the extent to which submesoscale stirring is driven by a cascade of energy down (in wavelength) from the mesoscale, versus a propagation of energy upwards from small mixing events (e.g., via generation of vortices). A key technical goal of our work is to develop the use of airborne LIDAR surveys of evolving dye experiments as a tool for studying submesoscale lateral dispersion.This annual report marks the end of year 4 of a 5 year study as part of the "Scalable Lateral Mixing and Coherent Turbulence" (a.k.a., LatMix) DRI. The main effort of the present work is a collaboration between J. Ledwell and E. Terray (WHOI), M. Sundermeyer (UMass Dartmouth), and B. Concannon (NAVAIR). This project is also being performed jointly with a collaborative NSF grant to J. Ledwell, E. Terray, and M. Sundermeyer (see "Related Projects" below). ONR support for this work included the airborne LIDAR operations as well as a substantial part of the field operations and analysis.

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“…Over the last two decades the role of gravity waves and inertia‐gravity waves in generating CAT has been established through aircraft observations [e.g., Pavelin et al , 2001; Lu et al , 2005, Lu and Koch , 2008], remote sensing [e.g., Muschinski , 1997], case studies using high‐resolution numerical simulations [e.g., Lane et al , 2004; Koch et al , 2005], and idealized studies using DNS [e.g., Fritts et al , 2009a, 2009b, 2009c]. Gravity waves can induce turbulence and mixing through breaking [e.g., Lelong and Dunkerton , 1998a, 1998b; Birch and Sundermeyer , 2011] or by perturbing atmospheric environments that are close to the threshold for local instabilities ( Ri ∼ Ri c ).…”

Section: Characterization Studiesmentioning

confidence: 99%

Sources and dynamics of turbulence in the upper troposphere and lower stratosphere: A review

Sharman

Trier

Lane

et al. 2012

Geophysical Research Letters

134

102

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1] Turbulence is a well-known hazard to aviation that is responsible for numerous injuries each year, with occasional fatalities, and is the underlying cause of many people's fear of air travel. Not only are turbulence encounters a safety issue, they also result in millions of dollars of operational costs to airlines, leading to increased costs passed on to the consumer. For these reasons, pilots, dispatchers, and air traffic controllers attempt to avoid turbulence wherever possible. Accurate forecasting of aviation-scale turbulence has been hampered in part by a lack of understanding of the underlying dynamical processes. However, more precise observations of turbulence encounters together with recent research into turbulence generation processes is helping to elucidate the detailed dynamical processes involved and is laying the foundation for improved turbulence forecasting and avoidance. In this paper we briefly review some of the more important recent observational, theoretical, and modeling results related to turbulence at cruise altitudes for commercial aircraft (i.e., the upper troposphere and lower stratosphere), and their implications for aviation turbulence forecasting. Citation: Sharman, R. D., S. B. Trier, T. P. Lane, and J. D. Doyle (2012), Sources and dynamics of turbulence in the upper troposphere and lower stratosphere: A review, Geophys.

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Breaking internal wave groups: Mixing and momentum fluxes

Cited by 10 publications

References 43 publications

Vortex Stability in a Large-Scale Internal Wave Shear

Vortex Stability in a Large-Scale Internal Wave Shear

LIDAR and Numerical Modeling Studies of Small-Scale Lateral Dispersion in the Ocean

Sources and dynamics of turbulence in the upper troposphere and lower stratosphere: A review

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