On the reflection of internal gravity waves

J. D. Whitehead

doi:10.1139/p70-231

On the reflection of internal gravity waves

Canadian Journal of Physics ◽

10.1139/p70-231 ◽

1970 ◽

Vol 48 (15) ◽

pp. 1830-1834

Author(s):

J. D. Whitehead

Keyword(s):

Phase Change ◽

Gravity Waves ◽

Relative Phase ◽

Internal Gravity Waves ◽

Acoustic Gravity Waves ◽

Wave Parameters ◽

Normal Propagation

Recently Einaudi and Hines discussed the fact that different wave parameters of acoustic–gravity waves may have different reflection heights. This raises the problem that there will be a range of heights over which one parameter is evanescent, whereas another parameter is in its normal propagation region. It is not obvious that for this second parameter the range of heights does not encompass many wavelengths and thus there would be a large relative phase change between the two parameters.However, it is shown that the extent of the relative phase change will often be less than 2π, and the conditions under which it may exceed 2π are derived.

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Trapped Gravity Waves and Their Association with Turbulence in a Large Thunderstorm Anvil during PECAN

Monthly Weather Review ◽

10.1175/mwr-d-18-0152.1 ◽

2018 ◽

Vol 146 (9) ◽

pp. 3031-3052 ◽

Cited By ~ 3

Author(s):

Stanley B. Trier ◽

Robert D. Sharman

Keyword(s):

Gravity Waves ◽

Relative Phase ◽

Deep Convection ◽

Internal Gravity Waves ◽

Static Stability ◽

Vertical Shear ◽

Radiosonde Data ◽

Local Minima ◽

Commercial Aviation ◽

Onset Of Turbulence

Abstract Geostationary Operational Environmental Satellite-14 (GOES-14) 1-km visible satellite data with 1-min frequency revealed horizontally propagating internal gravity waves emanating from tropopause-penetrating deep convection on 3–4 June 2015 during the Plains Elevated Convection at Night (PECAN) field experiment. These waves had horizontal wavelengths of ~6–8 km and approximate ground-relative phase speeds of 35 m s−1. PECAN radiosonde data are used to document the environment supporting the horizontally propagating gravity waves within the 200-km-long downstream thunderstorm anvil. Comparisons among soundings within the anvil core, at the downstream anvil edge, and outside of the anvil, together with supporting high-resolution numerical simulations, establish the importance of the storm-induced upper-tropospheric/lower-stratospheric (UTLS) outflow in providing conditions allowing vertical trapping of internal gravity waves over large horizontal distances within the mesoscale anvil. Turbulence was reported by commercial aviation in proximity to the gravity waves near the downstream anvil edge. The simulations suggest that the strongest turbulence was consistent with a mesoscale destabilization of the outer portion of the downstream anvil at elevations immediately below the outflow jet, where differential temperature advection owing to the strong associated vertical shear reduces static stability. The simulated gravity waves are trapped at this elevation and extend for several kilometers below. Local minima of moist gradient Richardson number occur immediately above the simulated warm gravity wave temperature perturbations at anvil base, suggesting a possible role these waves could play in establishing precise locations for the onset of turbulence.

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Wentzel–Kramers–Brillouin approximation for atmospheric waves

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.367 ◽

2015 ◽

Vol 777 ◽

pp. 260-290 ◽

Cited By ~ 8

Author(s):

Oleg A. Godin

Keyword(s):

Gravity Waves ◽

Acoustic Waves ◽

Ad Hoc ◽

Berry Phase ◽

Boussinesq Approximation ◽

Internal Gravity Waves ◽

Wkb Approximation ◽

Approximation Properties ◽

Atmospheric Waves ◽

Acoustic Gravity Waves

Ray and Wentzel–Kramers–Brillouin (WKB) approximations have long been important tools in understanding and modelling propagation of atmospheric waves. However, contradictory claims regarding the applicability and uniqueness of the WKB approximation persist in the literature. Here, we consider linear acoustic–gravity waves (AGWs) in a layered atmosphere with horizontal winds. A self-consistent version of the WKB approximation is systematically derived from first principles and compared to ad hoc approximations proposed earlier. The parameters of the problem are identified that need to be small to ensure the validity of the WKB approximation. Properties of low-order WKB approximations are discussed in some detail. Contrary to the better-studied cases of acoustic waves and internal gravity waves in the Boussinesq approximation, the WKB solution contains the geometric, or Berry, phase. The Berry phase is generally non-negligible for AGWs in a moving atmosphere. In other words, knowledge of the AGW dispersion relation is not sufficient for calculation of the wave phase.

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On the Correlativity between Atmospheric Gravity Waves and Various Weather Phenomena

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/026309238800700403 ◽

1988 ◽

Vol 7 (4) ◽

pp. 142-150

Author(s):

Xie Jin-Lai ◽

Yang Xun-Ren ◽

Li Ying-Bo ◽

Li Qi-Tai

Keyword(s):

Gravity Waves ◽

Internal Gravity Waves ◽

High Wind ◽

New Classification ◽

Practical Applications ◽

Acoustic Gravity Waves ◽

Wave Characteristics ◽

Whole Process ◽

Atmospheric Gravity ◽

Abnormal Weather

Acoustic Gravity Waves (AGW) and Internal Gravity Waves (IGW) concerned with various abnormal weather phenomena, such as storms, high wind, hail etc., in some local regions have been detected, recorded and studied. These waves, as a kind of perturbation with infrasonic frequenices, express different wave characteristics. Four to ten hours before the eruption of developing disastrous weathers, obvious perturbated waveforms can be recorded at a nearby infrasonic observatory. The analysis and understanding of these results has considerable practical meaning for the prediction of events. The spectral analyses for the whole process of hailing has been carried out, and a new classification for studying disastrous weather has been suggested. Furthermore, some possible practical applications of AGW and IGW to disaster forecasting have been discussed.

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Internal gravity and infrasound waves during a hurricane in Moscow On May 29, 2017

Известия Российской академии наук Физика атмосферы и океана ◽

10.31857/s0002-351555232-40 ◽

2019 ◽

Vol 55 (2) ◽

pp. 32-40

Author(s):

S. N. Kulichkov ◽

I. P. Chunchuzov ◽

O. E. Popov ◽

V. G. Perepelkin ◽

E. V. Golikova ◽

...

Keyword(s):

Gravity Waves ◽

Atmospheric Pressure ◽

Measurement Data ◽

Internal Gravity Waves ◽

Temporal Modulation ◽

Frequency Spectra ◽

Acoustic Gravity Waves ◽

Cold Fronts ◽

Phase Velocities ◽

The Waves

The results of recording of internal gravity waves (IGWs) and infrasound waves from the warm and cold fronts associated with the atmospheric storm passing through Moscow on May 29, 2017 are presented. The waves were recorded by a network of 4 microbarographs IFA–MGU–MSR–ZNS located in Moscow and Moscow region, and compared with the data of measurements of the parameters of infrasound waves at infrasound station IS43 in Dubna. We study the temporal changes in the characteristics of IGWs and infrasound waves (coherence, direction of propagation,phase velocities, characteristic periods and frequency spectra) with the passage of warm and cold fronts through the network. The transition from the gravity to the acoustic dispersive branch of acoustic-gravity waves due to an increase in frequency and the temporal modulation of the phase velocity of infrasound waves caused by IGWs are also studied. The measurement data for PM10 aerosol concentrations and NO2 gas concentrations at various locations in Moscow during a passage of atmospheric storm are presented. The possibility of detecting wave precursors of atmospheric storms simultaneously in variations of atmospheric pressure, wind velocity and aerosol concentrations is studied.

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Study of Propagation of Acoustic-Gravity Waves Generated by Tropospheric Heat Source

10.5194/egusphere-egu21-2755 ◽

2021 ◽

Author(s):

Yuliya Kurdyaeva ◽

Sergey Kshevetskii

Keyword(s):

Heat Source ◽

Gravity Waves ◽

Numerical Study ◽

Pressure Fluctuations ◽

Boundary Surface ◽

Internal Gravity Waves ◽

Problem Model ◽

Acoustic Gravity Waves ◽

Infrasonic Waves ◽

Comparison Results

&#160; &#160; &#160;The use of experimental data on pressure variations on the Earth's surface makes possible to study the propagation of acoustic-gravity waves from the lower to the upper atmosphere. However, a question arises: how the pressure on the Earth's surface is related to meteorological processes and how significant inaccuracy is allowed when replacing tropospheric meteorological sources instead experimentally observed pressure fluctuations on the Earth's surface.&#160; &#160; &#160;The problem of wave propagation from a tropospheric heat source was analytically studied to resolve this issue. Based on general assumptions about the tropospheric source and its parameters, an estimate of the waves that could be generated by such source was made. The study showed that the generation of internal gravity waves by a heat source cannot occur without the generation of infrasonic waves by this source. Therefore, infrasonic waves must also be taken into account. The source of infrasonic waves was defined and it was shown that in terms of power it is approximately equal to the source of internal gravity waves. Despite this, the amplitude of the generated infrasonic waves is less than the amplitude of the gravity ones, due to the fact that the source frequency is less than the acoustic cutoff frequency.&#160; &#160; &#160;In the numerical study of this problem, model local thermal small-sized tropospheric sources of waves operating at different frequencies were studied. Pressure fluctuations at the Earth's surface from the studied model source are recorded and then used at the boundary surface to calculate the propagation of waves upward from pressure fluctuations. Comparison results of calculations directly from a tropospheric source operating at infrasonic frequencies and from recorded pressure fluctuations on the Earth's surface showed that the wave pattern above the source, created directly by the tropospheric source, and from pressure variations recorded on the Earth's surface, practically coincide. In the case when the tropospheric source operates at the frequencies of internal gravity waves, the general coincidence of the two wave patterns also takes place. However, the quality of this match is lower. This happens due both to the typical features of the propagation of the internal gravity waves themselves, and to the fact that during the operation of such a source, infrasonic waves are additionally generated.&#160; &#160; &#160;The reported study was funded by RFBR and Kaliningrad region according to the research project &#8470; 19-45-390005.

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Acoustic gravity wave growth and damping in convecting plasma

Annales Geophysicae ◽

10.1007/s00585-994-0210-5 ◽

1994 ◽

Vol 12 (2/3) ◽

pp. 210-219

Author(s):

T. R. Robinson

Keyword(s):

Gravity Waves ◽

Plasma Flow ◽

Large Scale ◽

Flow Direction ◽

Internal Gravity Waves ◽

Flow Speed ◽

Convection Flow ◽

Feedback Effects ◽

Wave Growth ◽

Acoustic Gravity Waves

Abstract. The propagation of acoustic gravity waves through steadily convecting plasma in the thermosphere has been analysed theoretically. The growth and damping rates of internal gravity waves due to the feedback effects of wave-modulated Joule heating and Laplace forcing have been calculated. It is found that large convection flow velocities lead to the growth of large-scale internal gravity waves, whilst small- and medium-scale waves are heavily damped, under similar conditions. It has also been shown that wave growth is favoured for waves travelling against the plasma flow direction. The effects of critical coupling when wave phase speeds match the plasma flow speed have also been investigated. The results of these calculations are discussed in the context of the atmospheric energy budget and thermosphere-ionosphere coupling.

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