Gravity‐wave generation by thunderstorms observed with a vertically‐pointing 430 MHz radar

Larsen, M. F.; Swartz, Wesley E.; Woodman, R. F.

doi:10.1029/gl009i005p00571

Cited by 53 publications

(38 citation statements)

References 12 publications

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“…10, it is found that the smallest wavelength of which the wave is internal becomes larger when the phase velocity gets faster. Larsen et al (1982) observed stratospheric wave motions above tropospheric convections, and found a high frequency wave with a period of 6 min and the vertical wavelength of 7 km. The dominant waves in the present model simulation are consistent with these high frequency IGWs observed in the real atmosphere in spite of the difference of the convection mechanism.…”

Section: Convection and Igws Propagationmentioning

confidence: 99%

A non-hydrostatic and compressible 2-D model simulation of Internal Gravity Waves generated by convection

Goya

Miyahara

2014

Earth Planet Sp

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Generation of internal gravity waves (IGWs) by tropospheric convections and vertical propagation of the generated IGWs throughout the middle atmosphere are simulated by a non-hydrostatic compressible nonlinear two-dimensional numerical model.The present simulation demonstrates that (i) IGWs are generated by the tropospheric dry convections, (ii) zonal mean wind is decelerated by critical layer absorption of the generated IGWs in the upper tropospheric shear zone, (iii) secondary IGWs are radiated by the critical layer instability, and (iv) the secondary IGWs break down and accelerate zonal mean winds in the upper middle atmosphere.The detailed analyses show that (1) eastward propagating IGWs generated by the convection in tropospheric westerly with small wavelength of the order of 10 km and short period of the order of 10 min are dominant. It is found that the dominant waves are selected by a filtering effects of the prescribed westerly. (2) Several secondary IGWs with smaller horizontal wavelength than the primary IGW are radiated. The secondary IGWs propagate vertically in the form of wavepackets and break in the upper middle atmosphere due to local convective instability because of the exponential growth of the wave amplitudes with height. In the breaking region, the observed and theoretically predicted universal power law of the wind fluctuation, which states the m −3 dependence for the power spectra versus the vertical wavenumber m due to the wave saturation and breakdown, is also realized in the present model simulation.

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Section: Convection and Igws Propagationmentioning

confidence: 99%

A non-hydrostatic and compressible 2-D model simulation of Internal Gravity Waves generated by convection

Goya

Miyahara

2014

Earth Planet Sp

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“…It solves the linear solutions in a locally unsheared environment with a constant buoyancy frequency. Observations and simulations show that there are typically many small updrafts within the "envelope" of a convectively unstable region, which give rise to a GW spectrum concentrated at small-scales of ∼5-10 km (e.g., Larsen et al, 1982;Alexander et al, 1995). Our model neglects the individual updrafts which generate these small-scale GWs, as these GWs are not likely to propagate to the upper atmosphere and thermosphere (due to wave breaking, critical level absorption, and reflection in the stratosphere).…”

Section: Convective Plume Modelmentioning

confidence: 99%

“…Note that there is no mean response to a vertical body force. Since we are modeling the excitation of GWs from convective overshoot, which produces very high-frequency GWs with 5-20 min periods (e.g., Larsen et al, 1982;Alexander et al, 1995), we can neglect the Earth's rotation by setting f =0. Then k 2 ω 2 =k 2 H N 2 and A F =ω 2 F z /N 2 .…”

Section: Gravity Wave Solutions For Vertical Body Forcesmentioning

confidence: 99%

Reconstruction of the gravity wave field from convective plumes via ray tracing

2009

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Abstract. We implement gravity wave (GW) phases into our convective plume and anelastic ray trace models. This allows us to successfully reconstruct the GW velocity, temperature, and density perturbation amplitudes and phases in the Mesosphere-Lower-Thermosphere (MLT) via ray tracing (in real space) those GWs that are excited from a deep convective plume. We find that the ray trace solutions agree very well with the exact, isothermal, zero-wind, Fourier-Laplace solutions in the Boussinesq limit. This comparison also allows us to determine the normalization factor which converts the GW spectral amplitudes to real-space amplitudes in the ray trace model. This normalization factor can then be used for ray tracing GWs through varying temperature and wind profiles. We show that by adding GW reflection off the Earth's surface, the resulting GW spectrum has more power at larger vertical and horizontal wavelengths. We determine the form of the momentum flux and velocity spectra which allows for easy calculation of GW amplitudes in the MLT and thermosphere. Finally, we find that the reconstructed (ray traced) solution for a deep, convective plume with a duration much shorter than the buoyancy period does not equal the Fourier-Laplace Boussinesq solution; this is likely due to errors in the Boussinesq dispersion relation for very high frequency GWs.

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“…Hence, the unresolved questions related to the seed perturbation could be stated as: (1) possibility of insitu generation of the gravity waves through (a) motion of the solar terminator across the lower thermosphere, (b) evening F-layer rise permitting zonal wind acceleration and associated strong vertical shear (Anderson et al, 1982), and (c) deposition of momentum at z∼180 km from the dissipation of gravity waves from the lower atmosphere (Vadas and Fritts, 2006), (2) remote sources such as tropospheric convection activity that could produce upward propagating gravity waves (Rottger, 1981;Larsen and Swartz, 1982;Lane et al, 2003).…”

Section: Discussionmentioning

confidence: 99%

Role of gravity wavelike seed perturbations on the triggering of ESF – a case study from unique dayglow observations

et al. 2009

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Abstract. First observational evidence, from the Indian longitudes, for the presence of gravity wavelike perturbations with periods of 20-30 min, acting as probable seeds for Equatorial Spread F (ESF) irregularities is described. The study is based on the daytime optical measurements of the mesopause temperature and the intensity of the thermospheric O( 1 D) 630.0 nm dayglow emissions using the unique MultiWavelength Dayglow PhotoMeter from Trivandrum (8.5 • N; 77 • E; dip lat ∼0.5 • N), a dip equatorial station. Measurements during the equinoctial months of a solar maximum (2001) and a solar minimum year (2006) have been used in this study. It is shown that under identical background ionospheric conditions within a solar epoch, the power of the gravity waves have a deterministic role in the generation of ESF. The mesopause temperature simultaneously observed, indicate that possible source regions for these perturbations lie in the lower atmosphere.

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Gravity‐wave generation by thunderstorms observed with a vertically‐pointing 430 MHz radar

Cited by 53 publications

References 12 publications

A non-hydrostatic and compressible 2-D model simulation of Internal Gravity Waves generated by convection

A non-hydrostatic and compressible 2-D model simulation of Internal Gravity Waves generated by convection

Reconstruction of the gravity wave field from convective plumes via ray tracing

Role of gravity wavelike seed perturbations on the triggering of ESF – a case study from unique dayglow observations

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