Ray Tracing of Gravity Waves as a Possible Warning System for Tornadic Storms and Hurricanes

Hung, R. J.; Smith, R. E.

doi:10.1175/1520-0450(1978)017<0003:rtogwa>2.0.co;2

Cited by 57 publications

(20 citation statements)

References 15 publications

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“…Ray tracing has been used for decades for geophysical problems of interest (e.g., Jones, 1969;Marks and Eckermann, 1995;Cowling et al, 1971;Jones, 1984, 1987;Hung and Kuo, 1978;Hung and Smith, 1978;Lighthill, 1978;Gerrard et al, 2004;Hecht et al2004;Lin and Zhang, 2008). Our ray trace model is based on the formalism developed by Lighthill (1978), and allows the wind, density, and other background parameters to change slowly with altitude, horizontal location, and time.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

confidence: 99%

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

2009

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“…Jones, 1969;Marks and Eckermann, 1995;Cowling et al, 1971;Jones, 1984, 1987;Hung and Kuo, 1978;Hung and Smith, 1978;Lighthill, 1978;Gerrard et al, 2004;Hecht et al, 2004;Wrasse et al, 2009;Lin and Zhang, 2008). Although these past formalisms allowed for the propagation of GWs through varying 3-D winds and temperatures, they did not allow for the propagation of high-frequency GWs through a thermosphere containing realistic dissipation.…”

Section: Ray Trace Modelmentioning

confidence: 99%

Convection: the likely source of the medium-scale gravity waves observed in the OH airglow layer near Brasilia, Brazil, during the SpreadFEx campaign

et al. 2009

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Abstract. Six medium-scale gravity waves (GWs) with horizontal wavelengths of λ H =60-160 km were detected on four nights by Taylor et al. (2009) in the OH airglow layer near Brasilia, at 15 • S, 47 • W, during the Spread F Experiment (SpreadFEx) in Brazil in 2005. We reverse and forward ray trace these GWs to the tropopause and into the thermosphere using a ray trace model which includes thermospheric dissipation. We identify the convective plumes, convective clusters, and convective regions which may have generated these GWs. We find that deep convection is the highly likely source of four of these GWs. We pinpoint the specific deep convective plumes which likely excited two of these GWs on the nights of 30 September and 1 October. On these nights, the source location/time uncertainties were small and deep convection was sporadic near the modeled source locations. We locate the regions containing deep convective plumes and clusters which likely excited the other two GWs. The last 2 GWs were probably also excited from deep convection; however, they must have been ducted ∼500-700 km if so. Two of the GWs were likely downwards-propagating initially (after which they reflected upwards from the Earth's surface), while one of the GWs was likely upwards-propagating initially from the convective plume/cluster. We also estimate the amplitudes and vertical scales of these waves at the tropopause, and compare their scales with those from a simple, linear convection model. Finally, we calculate each GW's dissipation altitude, location, and amplitude. We find that the dissiCorrespondence to: S. L. Vadas (vasha@cora.nwra.com) pation altitude depends sensitively on the winds at and above the OH layer. We also find that several of these GWs may have penetrated to high enough altitudes to potentially seed equatorial spread F (ESF) if located somewhat farther from the magnetic equator.

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“…When propagating up to the upper atmosphere, GWs excited by TCs (Shen, 1982;Sun et al, 2007) bring forth the observable traveling ionospheric disturbances (TIDs) in the form of ionization in the F-region (Hung, 1977a, b). Using a reverse ray tracing technique, Hung and Kuo (1978a) and Hung and Smith (1978b) identified tropical cyclones as possible sources of GWs at the ionospheric heights.…”

Section: Introductionmentioning

confidence: 99%

Analysis of gravity-waves produced by intense tropical cyclones

2010

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Abstract. Conventional and wavelet methods are combined to characterize gravity-waves (GWs) produced by two intense tropical cyclones (TCs) in the upper troposphere and lower stratosphere (UT/LS) from GPS winsonde data. Analyses reveal large contribution of GWs induced by TCs to wave energy densities in the UT/LS. An increase in total energy density of about 30% of the climatological energy density in austral summer was estimated in the LS above Tromelin during TC Dina. Four distinct periods in GW activity in relation with TC Faxai stages is observed in the UT. Globally, GWs have periods of 6 h-2.5 days, vertical wavelenghts of 1-3 km and horizontal wavelengths <1000 km in the UT during the evolution of TCs. Horizontal wavelengths are longer in the LS and about 2200 km during TCs. Convective activity over the basin and GW energy density were modulated by mixed equatorial waves of 3-4 days, 6-8 days and 10-13 days confirmed by Hövmöller diagram, Fourier and wavelet analyses of OLR data. Moreover, location of GW sources is below the tropopause height when TCs are intense otherwise varies at lower tropospheric heights depending on the strength of convection. Finally, the maximum surface wind speeds of TCs Dina and Faxai can be linearly estimated with total energy densities.

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Ray Tracing of Gravity Waves as a Possible Warning System for Tornadic Storms and Hurricanes

Cited by 57 publications

References 15 publications

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

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

Convection: the likely source of the medium-scale gravity waves observed in the OH airglow layer near Brasilia, Brazil, during the SpreadFEx campaign

Analysis of gravity-waves produced by intense tropical cyclones

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