scholarly journals Spectral energy transfer of atmospheric gravity waves through sum and difference nonlinear interactions

2012 ◽  
Vol 30 (2) ◽  
pp. 303-315 ◽  
Author(s):  
K. M. Huang ◽  
A. Z. Liu ◽  
S. D. Zhang ◽  
F. Yi ◽  
Z. Li
Keyword(s):  
Energy Transfer ◽  
Gravity Waves ◽  
High Frequency ◽  
Energy Exchange ◽  
Low Frequency ◽  
Resonant Interaction ◽  
Resonant Excitation ◽  
Spectral Energy ◽  
Nonlinear Interactions ◽  
Resonant Interactions

Abstract. Nonlinear interactions of gravity waves are studied with a two-dimensional, fully nonlinear model. The energy exchanges among resonant and near-resonant triads are examined in order to understand the spectral energy transfer through interactions. The results show that in both resonant and near-resonant interactions, the energy exchange between two high frequency waves is strong, but the energy transfer from large to small vertical scale waves is rather weak. This suggests that the energy cascade toward large vertical wavenumbers through nonlinear interaction is inefficient, which is different from the rapid turbulence cascade. Because of considerable energy exchange, nonlinear interactions can effectively spread high frequency spectrum, and play a significant role in limiting wave amplitude growth and transferring energy into higher altitudes. In resonant interaction, the interacting waves obey the resonant matching conditions, and resonant excitation is reversible, while near-resonant excitation is not so. Although near-resonant interaction shows the complexity of match relation, numerical experiments show an interesting result that when sum and difference near-resonant interactions occur between high and low frequency waves, the wave vectors tend to approximately match in horizontal direction, and the frequency of the excited waves is also close to the matching value.

Observed Energy Exchange between Low-Frequency Flows and Internal Waves in the Gulf of Mexico

2018 ◽  
Vol 48 (4) ◽  
pp. 995-1008 ◽  
Author(s):  
Zhao Jing ◽  
Ping Chang ◽  
S. F. DiMarco ◽  
Lixin Wu
Keyword(s):  
Energy Transfer ◽  
Gulf Of Mexico ◽  
Internal Waves ◽  
High Frequency ◽  
Energy Exchange ◽  
Low Frequency ◽  
Net Energy ◽  
Energy Transfer Rate ◽  
Capture Mechanism

AbstractA long-term mooring array deployed in the northern Gulf of Mexico is used to analyze energy exchange between internal waves and low-frequency flows. In the subthermocline (245–450 m), there is a noticeable net energy transfer from low-frequency flows, defined as having a period longer than six inertial periods, to internal waves. The magnitude of energy transfer rate depends on the Okubo–Weiss parameter of low-frequency flows. A permanent energy exchange occurs only when the Okubo–Weiss parameter is positive. The near-inertial internal waves (NIWs) make major contribution to the energy exchange owing to their energetic wave stress and relatively stronger interaction with low-frequency flows compared to the high-frequency internal waves. There is some evidence that the permanent energy exchange between low-frequency flows and NIWs is attributed to the partial realization of the wave capture mechanism. In the periods favoring the occurrence of the wave capture mechanism, the horizontal propagation direction of NIWs becomes anisotropic and exhibits evident tendency toward that predicted from the wave capture mechanism, leading to pronounced energy transfer from low-frequency flows to NIWs.

scholarly journals Nonlinear interaction between acoustic gravity waves

1996 ◽  
Vol 14 (3) ◽  
pp. 304-308 ◽  
Author(s):  
P. Axelsson ◽  
J. Larsson ◽  
L. Stenflo
Keyword(s):  
Gravity Waves ◽  
Nonlinear Interaction ◽  
Low Frequency ◽  
Resonant Interaction ◽  
Coupling Coefficients ◽  
Symmetric Form ◽  
Frequency Limit ◽  
Acoustic Gravity Waves

Abstract. The resonant interaction between three acoustic gravity waves is considered. We improve on the results of previous authors and write the new coupling coefficients in a symmetric form. Particular attention is paid to the low-frequency limit.

Numerical Investigation of Mechanisms Underlying Oceanic Internal Gravity Wave Power-Law Spectra

2020 ◽  
Vol 50 (9) ◽  
pp. 2713-2733
Author(s):  
Yulin Pan ◽  
Brian K. Arbic ◽  
Arin D. Nelson ◽  
Dimitris Menemenlis ◽  
W. R. Peltier ◽  
...  
Keyword(s):  
Power Law ◽  
Gravity Waves ◽  
High Frequency ◽  
Internal Gravity Wave ◽  
Numerical Data ◽  
Field Measurements ◽  
Internal Gravity Waves ◽  
Collision Integral ◽  
Turbulence Theory ◽  
Nonlinear Interactions

AbstractWe consider the power-law spectra of internal gravity waves in a rotating and stratified ocean. Field measurements have shown considerable variability of spectral slopes compared to the high-wavenumber, high-frequency portion of the Garrett–Munk (GM) spectrum. Theoretical explanations have been developed through wave turbulence theory (WTT), where different power-law solutions of the kinetic equation can be found depending on the mechanisms underlying the nonlinear interactions. Mathematically, these are reflected by the convergence properties of the so-called collision integral (CL) at low- and high-frequency limits. In this work, we study the mechanisms in the formation of the power-law spectra of internal gravity waves, utilizing numerical data from the high-resolution modeling of internal waves (HRMIW) in a region northwest of Hawaii. The model captures the power-law spectra in broad ranges of space and time scales, with scalings ω−2.05±0.2 in frequency and m−2.58±0.4 in vertical wavenumber. The latter clearly deviates from the GM76 spectrum but is closer to a family of induced-diffusion-dominated solutions predicted by WTT. Our analysis of nonlinear interactions is performed directly on these model outputs, which is fundamentally different from previous work assuming a GM76 spectrum. By applying a bicoherence analysis and evaluations of modal energy transfer, we show that the CL is dominated by nonlocal interactions between modes in the power-law range and low-frequency inertial motions. We further identify induced diffusion and the near-resonances at its spectral vicinity as dominating the formation of power-law spectrum.

A multi-spacecraft analysis of energy transfer associated with near-Earth magnetic reconnection

2020 ◽  
Author(s):  
Sid Fadanelli ◽  
Benoit Lavraud ◽  
Francesco Califano
Keyword(s):  
Energy Transfer ◽  
High Frequency ◽  
Energy Exchange ◽  
Evolution Equations ◽  
Effective Energy ◽  
Large Database ◽  
Statistical Validity ◽  
Effective Energy Transfer ◽  
Energy Transfers ◽  
Plasma Theory

<p>We present an analysis of energy transfers in a reconnecting near-Earth plasma, obtained by interpreting MMS data within the framework of multi-fluid plasma theory. In our analysis, energy transfers are calculated and examined locally. This way, correlations between different mechanisms of energy exchange can be retrieved in all spatial and temporal detail provided by the high-frequency, multi-point sampling capacity of the four MMS satellites. <br>In particular, compressional effects are separated from effective sources in the energy density evolution equations, allowing to distinguish whether some effective energy transfer is occurring locally. A large database of MMS encounters with reconnecting current sheets is exploited in order to assess the statistical validity of all results presented.</p>

Turbulent bremsstrahlung instability of whistler mode in the presence of enhanced ion-acoustic fluctuations

1984 ◽  
Vol 31 (3) ◽  
pp. 477-485 ◽  
Author(s):  
S. N. Sarma ◽  
M. Nambu ◽  
S. Bujarbarua
Keyword(s):  
Growth Rate ◽  
Electric Fields ◽  
High Frequency ◽  
Low Frequency ◽  
Resonant Interaction ◽  
Plasma Instability ◽  
Whistler Mode ◽  
Acoustic Fluctuations ◽  
Ion Acoustic ◽  
Nonlinear Force

In the presence of a low-frequency ion-acoustic turbulence and a high-frequency whistler-mode test wave, a new plasma instability occurs owing to a nonlinear force which originates from the resonant interaction between electrons and modulated nonlinear electric fields. The growth rate of the whistler mode is calculated and compared with observations.

Energy transfer between external and internal gravity waves

1964 ◽  
Vol 19 (3) ◽  
pp. 465-478 ◽  
Author(s):  
F. K. Ball
Keyword(s):  
Energy Transfer ◽  
Internal Wave ◽  
Surface Waves ◽  
Shallow Water ◽  
Gravity Waves ◽  
External Surface ◽  
Internal Gravity Waves ◽  
Liquid System ◽  
Resonant Interactions ◽  
Non Linear

In a two-layer liquid system non-linear resonant interactions between a pair of external (surface) waves can result in transfer of energy to an internal wave when appropriate resonance conditions are satisfied. This energy transfer is likely to be more powerful than similar transfers between external waves. The shallow water case is discussed in detail.

A Distinction Between Different Types of Stall in a Centrifugal Compressor Stage

1986 ◽  
Vol 108 (1) ◽  
pp. 83-92 ◽  
Author(s):  
N. Ka¨mmer ◽  
M. Rautenberg
Keyword(s):  
Energy Transfer ◽  
Centrifugal Compressor ◽  
High Frequency ◽  
Low Frequency ◽  
Rotating Stall ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Pressure Transducers ◽  
Different Types ◽  
Probe Measurements

The flow at the stall line of a centrifugal compressor with vaneless diffuser was investigated at different speeds. A distinction between three kinds of stall phenomena could be made. One type of stall with regurgitation of fluid at the impeller inlet was of a nonperiodic character, whereas two different types of periodic stall appeared at higher speeds. The rotating nature of these two types of stall was verified from a comparison of signals of peripherally spaced pressure transducers. The low-frequency rotating stall exhibited features of diffuser generated stall and a lobe number of three was measured. From a detailed investigation of the high-frequency rotating stall, which included unsteady probe measurements upstream and downstream of the impeller, it can be shown that this type of rotating stall is generated in the impeller by a periodic breakdown of energy transfer from the rotor to the flow. This conclusion is supported by the distribution of shroud static pressures.

scholarly journals Excitation Mechanism of Mixed Rossby–Gravity Waves in the Equatorial Atmosphere: Role of the Nonlinear Interactions among Equatorial Waves

2005 ◽  
Vol 62 (5) ◽  
pp. 1446-1462 ◽  
Author(s):  
Carlos F. M. Raupp ◽  
Pedro L. Silva Dias
Keyword(s):  
Gravity Waves ◽  
Energy Exchange ◽  
Amazon Basin ◽  
Austral Summer ◽  
Numerical Results ◽  
High Signal ◽  
Equatorial Waves ◽  
Nonlinear Interactions ◽  
Mass Source ◽  
Mixed Modes

Abstract One possible explanation for the relatively high signal of the mixed Rossby–gravity waves observed in the tropical atmosphere is explored in this paper. This explanation is based on the nonlinear interactions among equatorial waves, and is made by adopting the nonlinear shallow water equations on the equatorial β plane. These equations are solved by a spectral method that uses the eigensolutions of the linear problem as the expansion basis. Numerical simulations are performed with a specified stationary mass source representative of the tropospheric heating associated with the typical convective activity over the Amazon Basin during the austral summer period. The numerical results show that the mixed Rossby–gravity waves are excited by a nonlinear mechanism in which the slow modes excited by the thermal forcing generate a quasigeostrophic basic state that supplies energy especially to the mixed Rossby–gravity waves with zonal wavenumbers 4 and 5, which have periods of the order of 4 days. The phase propagation of these unstable mixed modes leads to a periodic energy exchange between the mixed Rossby–gravity waves and the quasigeostrophic modes (Rossby and ultralong Kelvin modes). This regular nonlinear energy exchange implies a 4-day-cycle vacillation in the solution, which might be linked to the 4–6-day local oscillations in the dynamical field data throughout the Amazon region found in observational studies. Besides the importance of quasigeostrophic modes in the excitation of mixed Rossby–gravity waves, the numerical results also suggest that the predominance of the slow modes is crucial for maintaining the high signal of the unstable mixed modes, since these waves are strongly suppressed by the inclusion of the fast modes in the integration.

scholarly journals Nonlinear energy transfer to short gravity waves in the presence of long waves

1995 ◽  
Vol 289 ◽  
pp. 199-226 ◽  
Author(s):  
H. S. Ölmez ◽  
J. H. Milgram
Keyword(s):  
Energy Transfer ◽  
Gravity Waves ◽  
Wave Spectrum ◽  
Nonlinear Interactions ◽  
Physical Reason ◽  
Transfer Rates ◽  
Nonlinear Energy Transfer ◽  
Long Wave ◽  
Direct Numerical Method ◽  
Nonlinear Energy

Existing theories for calculating the energy transfer rates to gravity waves due to resonant nonlinear interactions among wave components whose lengths are long in comparison to wave elevations have been verified experimentally and are well accepted. There is uncertainty, however, about prediction of energy transfer rates within a set of waves having short to moderate lengths when these are present simultaneously with a long wave whose amplitude is not small in comparison to the short wavelengths. Here we implement both a direct numerical method that avoids small-amplitude approximations and a spectral method which includes perturbations of high order. These are applied to an interacting set of short- to intermediate-length waves with and without the presence of a large long wave. The same cases are also studied experimentally. Experimentally and numerical results are in reasonable agreement with the finding that the long wave does influence the energy transfer rates. The physical reason for this is identified and the implications for computations of energy transfer to short waves in a wave spectrum are discussed.

Spectral Slope of Vowels Produced by Tracheoesophageal Speakers

1991 ◽  
Vol 34 (2) ◽  
pp. 243-247 ◽  
Author(s):  
Yingyong Qi ◽  
Bernd Weinberg
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Frequency Component ◽  
Least Square ◽  
Group Differences ◽  
Spectral Energy ◽  
Frequency Range ◽  
Spectral Slope ◽  
Matching Procedure ◽  
Autocorrelation Method

Spectra of vowels were analyzed to determine whether differences exist between the spectral slope of vowels produced by tracheoesophageal (TE) speakers and normal speakers and, if so, to quantify such differences. The linear predictive autocorrelation method was used to calculate smoothed spectra and the spectra were normalized with respect to a low frequency component. Comparisons between normalized spectral energy within a selected high frequency range revealed that energy within this frequency range for vowels produced by TE speakers was significantly higher than that produced by normal speakers. A least-square distance matching procedure was used to quantify speaker group differences in the spectral slope of vowels. Average spectra of vowels produced by the normal speakers could be matched to average spectra of vowels produced by the TE speakers by decreasing the spectral slope of their vowels by 2–3 dB/octave.

Sign in / Sign up

Export Citation Format

Share Document