Anelastic Internal Wave Packet Evolution and Stability

Dosser, Hayley; Sutherland, Bruce

doi:10.1175/jas-d-11-097.1

Cited by 27 publications

(29 citation statements)

References 25 publications

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“… Franke and Robinson [1999] considered 2D simulations with and without mean flow interaction and found a similar tendency for more vigorous instability at lower altitudes when mean flow interactions were included. Similarly, Dosser and Sutherland [2011b] note a similar tendency for instability at lower altitudes when mean flow interactions are included in the simulation of wave packets. Our finding that saturation occurs below A GW = 1 is consistent with nonlinear diffusive theory [ Medvedev and Klaassen , 1995, 2000; Medvedev et al , 1998; Yiğit et al , 2008, 2009].…”

Section: Discussionmentioning

confidence: 54%

“…In reality, GWs are almost always organized into temporarily and spatially localized “packets” comprised of a collection of wave number components. Under a 2D idealization it is possible to simulate the processes leading up to wave breaking from packets and there are several interesting studies where this is done [e.g., Sutherland , 2001; Dosser and Sutherland , 2011a, 2011b]. Such studies shed light on the role of wave‐induced changes to the mean flow (self acceleration) and typically allow for a much richer spectrum of wave number components (and hence the opportunity for wave‐wave interactions) as compared to simulations of initially monochromatic waves on a compact periodic domain.…”

Section: Numerical Modelmentioning

confidence: 99%

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Numerical simulation of gravity wave breaking in the lower thermosphere

Lund¹,

Fritts²

2012

J. Geophys. Res.

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.[1] Numerical simulations are used to study gravity wave (GW) propagation, instability, and breaking in the lower thermosphere. Compressible effects are accounted for via an anelastic formulation of the equations of motion and we employ a realistic description of the background thermodynamic state. An initially low-amplitude, monochromatic GW with horizontal wavelength 60 km and intrinsic frequency N/3.7 is introduced at the lower boundary and allowed to propagate to higher altitudes. The GW steepens as it propagates upward and displays instability and breaking over the altitude range $120-160 km. The effects of momentum deposition due to viscous attenuation and wave breaking are studied by comparing simulations which either include or exclude induced changes to the mean wind. These two cases also bound the range of expected behavior for horizontally localized GW packets. When induced changes to the mean wind are excluded, instability and turbulence occur over a broad altitude range spanning several vertical wavelengths. In contrast, the region of instability and turbulence is confined to a much more limited altitude range when induced mean wind effects are included. Wave breaking and turbulence in this case are largely confined within a shear layer formed by GW momentum transport. In time, the shear layer evolves into a critical level which consumes nearly all of the incident GW energy.Citation: Lund, T. S., and D. C. Fritts (2012), Numerical simulation of gravity wave breaking in the lower thermosphere,

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Section: Discussionmentioning

confidence: 54%

Section: Numerical Modelmentioning

confidence: 99%

Numerical simulation of gravity wave breaking in the lower thermosphere

Lund¹,

Fritts²

2012

J. Geophys. Res.

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“…Gravity wave breaking can also cause a "self-acceleration" feedback mechanism whereby the breaking waves accelerate the mean wind, leading to a larger shear and more critical level filtering, which in turn can cause more wave breaking and dissipation. This can also act to confine instability to the shear layer that generates it [Franke and Robinson, 1999;Dosser and Sutherland, 2011;Lund and Fritts, 2012;Liu et al, 2014;Fritts et al, 2015]. This mechanism is not accounted for by linear theory, and capturing all turbulent scales accurately over long time scales requires 3-D direct numerical simulations [Andreassen et al, 1994;Fritts et al, 2009].…”

Section: Introductionmentioning

confidence: 99%

Numerical modeling of a multiscale gravity wave event and its airglow signatures over Mount Cook, New Zealand, during the DEEPWAVE campaign

et al. 2017

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A 2‐D nonlinear compressible model is used to simulate a large‐amplitude, multiscale mountain wave event over Mount Cook, NZ, observed as part of the Deep Propagating Gravity Wave Experiment (DEEPWAVE) campaign and to investigate its observable signatures in the hydroxyl (OH) layer. The campaign observed the presence of a λx=200 km mountain wave as part of the 22nd research flight with amplitudes of >20 K in the upper stratosphere that decayed rapidly at airglow heights. Advanced Mesospheric Temperature Mapper (AMTM) showed the presence of small‐scale (25–28 km) waves within the warm phase of the large mountain wave. The simulation results show rapid breaking above 70 km altitude, with the preferential formation of almost‐stationary vortical instabilities within the warm phase front of the mountain wave. An OH airglow model is used to identify the presence of small‐scale wave‐like structures generated in situ by the breaking of the mountain wave that are consistent with those seen in the observations. While it is easy to interpret these feature as waves in OH airglow data, a considerable fraction of the features are in fact instabilities and vortex structures. Simulations suggest that a combination of a large westward perturbation velocity and shear, in combination with strong perturbation temperature gradients, causes both dynamic and convective instability conditions to be met particularly where the wave wind is maximized and the temperature gradient is simultaneously minimized. This leads to the inevitable breaking and subsequent generation of smaller‐scale waves and instabilities which appear most prominent within the warm phase front of the mountain wave.

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“…The theory as a whole is nonlinear, with a two-way interaction between finite-amplitude waves and mean flow, and a full consideration of the interaction with and between all nonlinearly induced higher harmonics, found to be negligibly weak in the IGW case, but not in the GM case. Processes resulting from the interaction between waves and a self-induced mean wind (Fritts and Dunkerton, 1984;Sutherland, 2001Sutherland, , 2006Dosser and Sutherland, 2011) are included in such formulations, as demonstrated, e.g. by Rieper et al (2013) and Muraschko et al (2015).…”

Section: Discussionmentioning

confidence: 99%

The interaction between synoptic‐scale balanced flow and a finite‐amplitude mesoscale wave field throughout all atmospheric layers: weak and moderately strong stratification

Achatz

Ribstein

Senf

et al. 2016

Quart J Royal Meteoro Soc

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The interaction between locally monochromatic finite-amplitude mesoscale waves, their nonlinearly induced higher harmonics, and a synoptic-scale flow is reconsidered, both in the tropospheric regime of weak stratification and in the stratospheric regime of moderately strong stratification. A review of the basic assumptions of quasi-geostrophic theory on an f -plane yields all synoptic scales in terms of a minimal number of natural variables, i.e. two out of the speed of sound, gravitational acceleration and Coriolis parameter. The wave scaling is defined so that all spatial and temporal scales are shorter by one order in the Rossby number, and by assuming their buoyancy field to be close to static instability. WKB theory is applied, with the Rossby number as scale separation parameter, combined with a systematic Rossby-number expansion of all fields. Classic results for synoptic-scale-flow balances and inertia-gravity-wave (IGW) dynamics are recovered. These are supplemented by explicit expressions for the interaction between mesoscale geostrophic modes (GMs), a possibly somewhat overlooked agent of horizontal coupling in the atmosphere, and the synoptic-scale flow. It is shown that IGW higher harmonics are slaved to the basic IGW, and that their amplitude is one order of magnitude smaller than the basic-wave amplitude. GM higher harmonics are not that weak and they are in intense nonlinear interaction between themselves and the basic GM. Compressible dynamics plays a significant role in the stratospheric stratification regime, where anelastic theory would yield insufficient results. Supplementing classic derivations, it is moreover shown that, in the absence of mesoscale waves, quasi-geostrophic theory holds also in the stratospheric stratification regime.

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Anelastic Internal Wave Packet Evolution and Stability

Cited by 27 publications

References 25 publications

Numerical simulation of gravity wave breaking in the lower thermosphere

Numerical simulation of gravity wave breaking in the lower thermosphere

Numerical modeling of a multiscale gravity wave event and its airglow signatures over Mount Cook, New Zealand, during the DEEPWAVE campaign

The interaction between synoptic‐scale balanced flow and a finite‐amplitude mesoscale wave field throughout all atmospheric layers: weak and moderately strong stratification

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