The interaction between gravity waves and solar tides in a linear tidal model with a 4‐D ray‐tracing gravity‐wave parameterization

<p>Ionospheric Total Electron Content (TEC) data from ground-based Global Positioning System (GPS) receiver networks have been used previously to detect Travelling Ionospheric Disturbances (TIDs). The TIDs have been shown to arise through coupling of lower atmosphere with the Ionosphere with Gravity Waves as the coupling mechanism. Gravity Waves generated by earthquakes, tsunamis, volcanoes, topography, convection and even solar eclipses have been detected using GPS TEC data. In this study, we identify Gravity Wave signatures in GPS TEC data derived from the Sumatran GPS Array (SuGAr) network. SuGAr is a network of 49 ground-based GPS stations along the convergent plate boundary between Indo-Australian and Asian tectonic plates in western Sumatra, Indonesia. Since initiation in 2002, data from SuGAr has primarily been used to study earthquakes and plate-tectonics in south-east Asia. Due to its location along the seismically-active region, SuGAr can provide valuable data for studying co-seismic Gravity Waves triggered by terrestrial-atmosphere coupling. Frequent occurrence of deep convective clouds in tropical region implies that SuGAr data also provides a unique opportunity to study atmospheric waves generated by convection.&#160;</p><p>We have identified Gravity Waves across a wide spectrum corresponding to seismic and tropical convection events in Sumatran region. Upon identifying the wave signatures, we characterized the wave parameters and identified the wave sources through suitable ray tracing calculations. In this paper we show acoustic-gravity waves generated by the 2012 Sumatra great earthquake sequence consisting of 2 largest strike slip earthquakes ever recorded. Spectral analysis indicates the presence of fundamental resonant frequencies for solid Earth-atmosphere coupling. Using a geometric ray tracing method, we also trace the waves very close to the reported epicentres of the double earthquake sequence. We also discuss inertia-gravity waves generated due to convection in South-East Asia using SuGAr TEC data for 2018. Indication of deep convective clouds is confirmed through satellite-based cloud top brightness temperature data.&#160; Ray tracing is performed to further trace the observed waves to the convective system location.</p>

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Superposition of gravity waves with different propagation characteristics observed by airborne and space-borne infrared sounders

10.5194/acp-2020-327 ◽

2020 ◽

Cited By ~ 1

Author(s):

Isabell Krisch ◽

Manfred Ern ◽

Lars Hoffmann ◽

Peter Preusse ◽

Cornelia Strube ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Wave ◽

Gravity Waves ◽

Decomposition Method ◽

Wave Packets ◽

Wave Structure ◽

Multiple Wave ◽

Wave Decomposition ◽

D Wave ◽

Middle Stratosphere

Abstract. A complex gravity wave structure consisting of a superposition of multiple wave packets was observed above southern Scandinavia on 28 January 2016 with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA). The tomographic measurement capability of GLORIA enabled a detailed 3-D reconstruction of the gravity wave field and the identification of multiple wave packets with different horizontal and vertical scales. The larger-scale gravity waves with horizontal wavelengths 5 around 400 km could be characterised using a 3-D wave-decomposition method. For the characterization of the smaller-scale wave components with horizontal wavelengths below 200 km, the 3-D wave-decomposition method needs to be further improved in the future. For the larger-scale gravity wave components, a combination of gravity-wave ray-tracing calculations and ERA5 reanalysis fields identified orography as well as a jet-exit region and a low pressure system as possible sources. All gravity waves propagate 10 upward into the middle stratosphere, but only the orographic waves stay directly above their source. The comparison with ERA5 also shows that ray-tracing provides reasonable results even for such complex cases with multiple overlapping wave packets. AIRS measurements in the middle stratosphere support these findings, even though their coarse vertical resolution barely resolves the observed wave structure in this case study. The high-resolution GLORIA observations are therefore an important source of information on gravity wave characteristics in the upper troposphere and lower stratosphere region.

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Mesospheric gravity waves observed near equatorial and low–middle latitude stations: wave characteristics and reverse ray tracing results

Annales Geophysicae ◽

10.5194/angeo-24-3229-2006 ◽

2006 ◽

Vol 24 (12) ◽

pp. 3229-3240 ◽

Cited By ~ 19

Author(s):

C. M. Wrasse ◽

T. Nakamura ◽

H. Takahashi ◽

A. F. Medeiros ◽

M. J. Taylor ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Wave ◽

Gravity Waves ◽

Source Region ◽

Phase Speed ◽

Middle Latitude ◽

Wave Source ◽

Middle Latitudes ◽

Summer Time ◽

The Waves

Abstract. Gravity wave signatures were extracted from OH airglow observations using all-sky CCD imagers at four different stations: Cachoeira Paulista (CP) (22.7° S, 45° W) and São João do Cariri (7.4° S, 36.5° W), Brazil; Tanjungsari (TJS) (6.9° S, 107.9° E), Indonesia and Shigaraki (34.9° N, 136° E), Japan. The gravity wave parameters are used as an input in a reverse ray tracing model to study the gravity wave vertical propagation trajectory and to estimate the wave source region. Gravity waves observed near the equator showed a shorter period and a larger phase velocity than those waves observed at low-middle latitudes. The waves ray traced down into the troposphere showed the largest horizontal wavelength and phase speed. The ray tracing results also showed that at CP, Cariri and Shigaraki the majority of the ray paths stopped in the mesosphere due to the condition of m2<0, while at TJS most of the waves are traced back into the troposphere. In summer time, most of the back traced waves have their final position stopped in the mesosphere due to m2<0 or critical level interactions (|m|→∞), which suggests the presence of ducting waves and/or waves generated in-situ. In the troposphere, the possible gravity wave sources are related to meteorological front activities and cloud convections at CP, while at Cariri and TJS tropical cloud convections near the equator are the most probable gravity wave sources. The tropospheric jet stream and the orography are thought to be the major responsible sources for the waves observed at Shigaraki.

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First tomographic observations of gravity waves by the infrared limb imager GLORIA

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-14937-2017 ◽

2017 ◽

Vol 17 (24) ◽

pp. 14937-14953 ◽

Cited By ~ 25

Author(s):

Isabell Krisch ◽

Peter Preusse ◽

Jörn Ungermann ◽

Andreas Dörnbrack ◽

Stephen D. Eckermann ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Wave ◽

Gravity Waves ◽

General Circulation ◽

Wave Packets ◽

Source Region ◽

General Circulation Models ◽

Climate Projections ◽

Flight Pattern ◽

The Waves

Abstract. Atmospheric gravity waves are a major cause of uncertainty in atmosphere general circulation models. This uncertainty affects regional climate projections and seasonal weather predictions. Improving the representation of gravity waves in general circulation models is therefore of primary interest. In this regard, measurements providing an accurate 3-D characterization of gravity waves are needed. Using the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA), the first airborne implementation of a novel infrared limb imaging technique, a gravity wave event over Iceland was observed. An air volume disturbed by this gravity wave was investigated from different angles by encircling the volume with a closed flight pattern. Using a tomographic retrieval approach, the measurements of this air mass at different angles allowed for a 3-D reconstruction of the temperature and trace gas structure. The temperature measurements were used to derive gravity wave amplitudes, 3-D wave vectors, and direction-resolved momentum fluxes. These parameters facilitated the backtracing of the waves to their sources on the southern coast of Iceland. Two wave packets are distinguished, one stemming from the main mountain ridge in the south of Iceland and the other from the smaller mountains in the north. The total area-integrated fluxes of these two wave packets are determined. Forward ray tracing reveals that the waves propagate laterally more than 2000 km away from their source region. A comparison of a 3-D ray-tracing version to solely column-based propagation showed that lateral propagation can help the waves to avoid critical layers and propagate to higher altitudes. Thus, the implementation of oblique gravity wave propagation into general circulation models may improve their predictive skills.

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Superposition of gravity waves with different propagation characteristics observed by airborne and space-borne infrared sounders

Atmospheric Chemistry and Physics ◽

10.5194/acp-20-11469-2020 ◽

2020 ◽

Vol 20 (19) ◽

pp. 11469-11490

Author(s):

Isabell Krisch ◽

Manfred Ern ◽

Lars Hoffmann ◽

Peter Preusse ◽

Cornelia Strube ◽

...

Keyword(s):

Ray Tracing ◽

Gravity Wave ◽

Gravity Waves ◽

Wave Packets ◽

Pressure System ◽

Multiple Wave ◽

Measurement Capability ◽

Wave Ray ◽

Complex Cases ◽

Middle Stratosphere

Abstract. Many gravity wave analyses, based on either observations or model simulations, assume the presence of only a single dominant wave. This paper shows that there are much more complex cases with gravity waves from multiple sources crossing each others' paths. A complex gravity wave structure consisting of a superposition of multiple wave packets was observed above southern Scandinavia on 28 January 2016 with the Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA). The tomographic measurement capability of GLORIA enabled a detailed 3-D reconstruction of the gravity wave field and the identification of multiple wave packets with different horizontal and vertical scales. The larger-scale gravity waves with horizontal wavelengths of around 400 km could be characterised using a 3-D wave-decomposition method. The smaller-scale wave components with horizontal wavelengths below 200 km were discussed by visual inspection. For the larger-scale gravity wave components, a combination of gravity-wave ray-tracing calculations and ERA5 reanalysis fields identified orography as well as a jet-exit region and a low-pressure system as possible sources. All gravity waves are found to propagate upward into the middle stratosphere, but only the orographic waves stay directly above their source. The comparison with ERA5 also shows that ray tracing provides reasonable results even for such complex cases with multiple overlapping wave packets. Despite their coarser vertical resolution compared to GLORIA measurements, co-located AIRS measurements in the middle stratosphere are in good agreement with the ray tracing and ERA5 results, proving once more the validity of simple ray-tracing models. Thus, this paper demonstrates that the high-resolution GLORIA observations in combination with simple ray-tracing calculations can provide an important source of information for enhancing our understanding of gravity wave propagation.

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Influence of the cloud-level neutral layer on the vertical propagation of topographically generated gravity waves on Venus

Earth Planets and Space ◽

10.1186/s40623-019-1106-7 ◽

2019 ◽

Vol 71 (1) ◽

Author(s):

Takeru Yamada ◽

Takeshi Imamura ◽

Tetsuya Fukuhara ◽

Makoto Taguchi

Keyword(s):

Layer Thickness ◽

Gravity Wave ◽

Local Time ◽

Gravity Waves ◽

Analytical Approach ◽

Wave Activity ◽

Neutral Layer ◽

Low Latitudes ◽

Vertical Propagation ◽

The Waves

AbstractThe reason for stationary gravity waves at Venus’ cloud top to appear mostly at low latitudes in the afternoon is not understood. Since a neutral layer exists in the lower part of the cloud layer, the waves should be affected by the neutral layer before reaching the cloud top. To what extent gravity waves can propagate vertically through the neutral layer has been unclear. To examine the possibility that the variation of the neutral layer thickness is responsible for the dependence of the gravity wave activity on the latitude and the local time, we investigated the sensitivity of the vertical propagation of gravity waves on the neutral layer thickness using a numerical model. The results showed that stationary gravity waves with zonal wavelengths longer than 1000 km can propagate to the cloud-top level without notable attenuation in the neutral layer with realistic thicknesses of 5–15 km. This suggests that the observed latitudinal and local time variation of the gravity wave activity should be attributed to processes below the cloud. An analytical approach also showed that gravity waves with horizontal wavelengths shorter than tens of kilometers would be strongly attenuated in the neutral layer; such waves should originate in the altitude region above the neutral layer.

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The nonlinear effects on the characteristics of gravity wave packets: dispersion and polarization relations

Annales Geophysicae ◽

10.1007/s00585-000-1316-z ◽

2000 ◽

Vol 18 (10) ◽

pp. 1316-1324 ◽

Cited By ~ 13

Author(s):

S.-D. Zhang ◽

F. Yi ◽

J.-F. Wang

Keyword(s):

Gravity Wave ◽

Gravity Waves ◽

Middle Atmosphere ◽

Wave Packets ◽

Nonlinear Effects ◽

Wave Theory ◽

Nonlinear Propagation ◽

Waves And Tides ◽

Time Variations ◽

Isothermal Atmosphere

Abstract. By analyzing the results of the numerical simulations of nonlinear propagation of three Gaussian gravity-wave packets in isothermal atmosphere individually, the nonlinear effects on the characteristics of gravity waves are studied quantitatively. The analyses show that during the nonlinear propagation of gravity wave packets the mean flows are accelerated and the vertical wavelengths show clear reduction due to nonlinearity. On the other hand, though nonlinear effects exist, the time variations of the frequencies of gravity wave packets are close to those derived from the dispersion relation and the amplitude and phase relations of wave-associated disturbance components are consistent with the predictions of the polarization relation of gravity waves. This indicates that the dispersion and polarization relations based on the linear gravity wave theory can be applied extensively in the nonlinear region.Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides)

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GRAVITY-WAVE DETECTORS AS PROBES OF EXTRA DIMENSIONS

International Journal of Modern Physics D ◽

10.1142/s0218271805007905 ◽

2005 ◽

Vol 14 (12) ◽

pp. 2347-2353 ◽

Cited By ~ 1

Author(s):

CHRIS CLARKSON ◽

ROY MAARTENS

Keyword(s):

Black Holes ◽

String Theory ◽

Gravity Wave ◽

Gravity Waves ◽

Extra Dimensions ◽

State Of The Art ◽

Three Dimensional ◽

Observable Universe ◽

Dimensional Spacetime ◽

Higher Dimensional

If string theory is correct, then our observable universe may be a three-dimensional "brane" embedded in a higher-dimensional spacetime. This theoretical scenario should be tested via the state-of-the-art in gravitational experiments — the current and upcoming gravity-wave detectors. Indeed, the existence of extra dimensions leads to oscillations that leave a spectroscopic signature in the gravity-wave signal from black holes. The detectors that have been designed to confirm Einstein's prediction of gravity waves, can in principle also provide tests and constraints on string theory.

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A statistical study of gravity waves from radiosonde observations at Wuhan (30° N, 114° E) China

Annales Geophysicae ◽

10.5194/angeo-23-665-2005 ◽

2005 ◽

Vol 23 (3) ◽

pp. 665-673 ◽

Cited By ~ 37

Author(s):

S. D. Zhang ◽

F. Yi

Keyword(s):

Gravity Wave ◽

Gravity Waves ◽

Extreme Values ◽

Dynamical Instability ◽

Strong Wind ◽

Data Set ◽

Height Range ◽

Wave Parameters ◽

Thermal Structures ◽

Radiosonde Observation

Abstract. Several works concerning the dynamical and thermal structures and inertial gravity wave activities in the troposphere and lower stratosphere (TLS) from the radiosonde observation have been reported before, but these works were concentrated on either equatorial or polar regions. In this paper, background atmosphere and gravity wave activities in the TLS over Wuhan (30° N, 114° E) (a medium latitudinal region) were statistically studied by using the data from radiosonde observations on a twice daily basis at 08:00 and 20:00 LT in the period between 2000 and 2002. The monthly-averaged temperature and horizontal winds exhibit the essential dynamic and thermal structures of the background atmosphere. For avoiding the extreme values of background winds and temperature in the height range of 11-18km, we studied gravity waves, respectively, in two separate height regions, one is from ground surface to 10km (lower part), and the other is within 18-25km (upper part). In total, 791 and 1165 quasi-monochromatic inertial gravity waves were extracted from our data set for the lower and upper parts, respectively. The gravity wave parameters (intrinsic frequencies, amplitudes, wavelengths, intrinsic phase velocities and wave energies) are calculated and statistically studied. The statistical results revealed that in the lower part, there were 49.4% of gravity waves propagating upward, and the percentage was 76.4% in the upper part. Moreover, the average wave amplitudes and energies are less than those at the lower latitudinal regions, which indicates that the gravity wave parameters have a latitudinal dependence. The correlated temporal evolution of the monthly-averaged wave energies in the lower and upper parts and a subsequent quantitative analysis strongly suggested that at the observation site, dynamical instability (strong wind shear) induced by the tropospheric jet is the main excitation source of inertial gravity waves in the TLS.

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