scholarly journals Atmospheric Gravity Waves and Effects in the Upper Atmosphere Associated with Tsunamis

10.5772/13577 ◽  
2011 ◽  
Author(s):  
Michael P.
Keyword(s):  
Gravity Waves ◽  
Upper Atmosphere ◽  
Atmospheric Gravity Waves ◽  
Atmospheric Gravity

Propagation factors influencing observations of resonances of atmospheric gravity waves

2020 ◽  
Author(s):  
Nikolay Zabotin ◽  
Oleg Godin
Keyword(s):  
Wave Packet ◽  
Gravity Waves ◽  
Numerical Solutions ◽  
Broad Band ◽  
Ground Level ◽  
Hf Radar ◽  
Upper Atmosphere ◽  
Atmospheric Gravity Waves ◽  
Atmospheric Wave ◽  
Atmospheric Gravity

<p>Observations of the ionosphere with the airglow, GPS-TEC, and HF radar techniques reveal a resonance-kind response of the middle and upper atmosphere to broad-band excitation by earthquakes, volcano eruptions, and convective storms. The resonances occur at such frequencies that an atmospheric wave, which is radiated at the ground level and is reflected from a turning point in the middle or upper atmosphere, upon return to the ground level satisfies boundary conditions on the ground. The "buoyancy" resonances (resonances of atmospheric gravity waves) with periods from several minutes and up to several hours arise in addition to well-known "acoustic" resonances with periods of about 3–4 minutes. The buoyancy resonances occur on the gravity branch of the dispersion relation for the acoustic-gravity waves. Infragravity waves in the ocean covering the same frequency band may serve as an efficient source of excitation of the buoyancy resonances. We have obtained dispersion relations for buoyancy resonances earlier. In this paper we investigate the influence of specific propagation characteristics of the gravity waves (their oblique propagation and dissipative attenuation) on conditions of their observation. We use  asymptotic (WKB and ray tracing) methods to investigate relationship between the gravity wave skip distance and the dimensions of typical infragravity wave packets in the oceans and find that conditions can be met for interaction of the same atmospheric wave packet with the same ocean wave packet. The dissipative attenuation eliminates some of the resonance modes, but still many of them remain intact. We use numerical solutions of the full wave equation to confirm results obtained by asymptotic methods. Calculations of this kind demonstrate a possibility of resonance-like behavior of the gravity waves in situations when partial reflections (caused by extrema of the refractive index) appear in addition to the total reflection. Unlike acoustic resonances, buoyancy resonances exhibit high sensitivity to the wind velocity profile and its variations. Non-stationarity of the atmosphere is an important factor limiting possibilities to observe the buoyancy resonances. Nevertheless, relatively low threshold for meeting all other conditions for their appearance and temporal/geographical diversity of the atmosphere makes it still quite probable to see their manifestations. The resonances correspond to most efficient coupling between the atmosphere and its lower boundary and are promising for detection of such coupling.</p>

THE VISCOUS DAMPING OF ATMOSPHERIC GRAVITY WAVES

1963 ◽  
Vol 41 (12) ◽  
pp. 1935-1948 ◽  
Author(s):  
M. L. V. Pitteway ◽  
C. O. Hines
Keyword(s):  
Gravity Waves ◽  
Thermal Conduction ◽  
Upper Atmosphere ◽  
Viscous Damping ◽  
Atmospheric Gravity Waves ◽  
Atmospheric Gravity

Dissipation produced by viscous damping and thermal conduction is important in the study of atmospheric gravity waves, which are themselves important in a study of "irregular" motions in the upper atmosphere. The mathematics of this damping is considered in some detail here, and charts are given to assess the effects of viscous damping and thermal conduction at meteor heights in the upper atmosphere. The results of this paper are consistent with the conclusions of an earlier analysis, insofar as the two overlap, and extend the range of conditions considered.

scholarly journals Preliminary Dual-Satellite Observations of Atmospheric Gravity Waves in Airglow

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 650
Author(s):  
Jia Yue ◽  
Septi Perwitasari ◽  
Shuang Xu ◽  
Yuta Hozumi ◽  
Takuji Nakamura ◽  
...  
Keyword(s):  
Gravity Waves ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Numerical Models ◽  
Space Station ◽  
Upper Atmosphere ◽  
Lower Atmosphere ◽  
Atmospheric Gravity Waves ◽  
Spectral Imager ◽  
Atmospheric Gravity

Atmospheric gravity waves (AGWs) are among the important energy and momentum transfer mechanisms from the troposphere to the middle and upper atmosphere. Despite their understood importance in governing the structure and dynamics of these regions, mesospheric AGWs remain poorly measured globally, and largely unconstrained in numerical models. Since late 2011, the Suomi National Polar-orbiting Partnership (NPP) Visible/Infrared Imaging Radiometer Suite (VIIRS) day–night band (DNB) has observed global AGWs near the mesopause by virtue of its sensitivity to weak emissions of the OH* Meinel bands. The wave features, detectable at 0.75 km spatial resolution across its 3000 km imagery swath, are often confused by the upwelling emission of city lights and clouds reflecting downwelling nightglow. The Ionosphere, Mesosphere, upper Atmosphere and Plasmasphere (IMAP)/ Visible and near-Infrared Spectral Imager (VISI) O2 band, an independent measure of the AGW structures in nightglow based on the International Space Station (ISS) during 2012–2015, contains much less noise from the lower atmosphere. However, VISI offers much coarser resolution of 14–16 km and a narrower swath width of 600 km. Here, we present preliminary results of comparisons between VIIRS/DNB and VISI observations of AGWs, focusing on several concentric AGW events excited by the thunderstorms over Eastern Asia in August 2013. The comparisons point toward suggested improvements for future spaceborne airglow sensor designs targeting AGWs.

Impact of atmospheric gravity waves on the Martian global water cycle during dust storms

2021 ◽  
Author(s):  
Dmitry Shaposhnikov ◽  
Alexander Medvedev ◽  
Alexander Rodin ◽  
Paul Hartogh
Keyword(s):  
Water Vapor ◽  
Gravity Waves ◽  
Dust Storm ◽  
Water Cycle ◽  
Dust Storms ◽  
Upper Atmosphere ◽  
Atmospheric Gravity Waves ◽  
Global Water Cycle ◽  
Atmospheric Gravity ◽  
Global Water

<p>Effects of atmospheric gravity waves (GWs) on the global water cycle in the middle and high atmosphere of Mars during the global dust storms (Martian years 28 and 34) have been studied for the first time using a general circulation model. Dust storm simulations were compared with those utilizing the climatological distribution of dust in the absence of a GW parameterization. The dust storm scenarios are based on the observations of the dust optical depth by the Mars Climate Sounder instrument on board Mars Reconnaissance Orbiter. The simulations show that accounting for the influence of GWs leads to a change in the concentration of water vapor in the thermosphere. The most significant effect of GWs is twofold. First, cooling of the thermosphere at the poles leads to a decrease in the water vapor abundance during certain periods. Second, heating in the regions representing the main channels of water supply to the upper atmosphere (the so-called water "pump" mechanism) increases, on the contrary, its concentration. Since the temperature increase provides more intensive atmospheric mixing, and also expands the supply channel through an increase in saturation pressure. The dynamic balance of these basic mechanisms drives the changes in the distribution of water vapor in the upper atmosphere. Dust storms enhance pumping of water vapor into the upper atmosphere. Seasonal differences in the storm occurrences in different years allow for tracking the paths of water vapor transport to the upper atmosphere.</p>

scholarly journals Observation evidences of atmospheric Gravity Waves induced by seismic activity from analysis of subionospheric LF signal spectra

2007 ◽  
Vol 7 (5) ◽  
pp. 625-628 ◽  
Author(s):  
A. Rozhnoi ◽  
M. Solovieva ◽  
O. Molchanov ◽  
P.-F. Biagi ◽  
M. Hayakawa
Keyword(s):  
Gravity Waves ◽  
Fresnel Zone ◽  
Signal Amplitude ◽  
Magnetic Storms ◽  
Frequency Range ◽  
Atmospheric Gravity Waves ◽  
Period Range ◽  
Before And After ◽  
Atmospheric Gravity ◽  
Large Earthquakes

Abstract. We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.

scholarly journals A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes

1997 ◽  
Vol 15 (8) ◽  
pp. 1048-1056 ◽  
Author(s):  
R. L. Balthazor ◽  
R. J. Moffett
Keyword(s):  
Gravity Waves ◽  
Large Scale ◽  
Ionospheric Disturbance ◽  
Magnetic Equator ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Waves ◽  
Opposite Hemisphere ◽  
Travelling Ionospheric Disturbances ◽  
F Region ◽  
Atmospheric Gravity

Abstract. A global coupled thermosphere-ionosphere-plasmasphere model is used to simulate a family of large-scale imperfectly ducted atmospheric gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs) originating at conjugate magnetic latitudes in the north and south auroral zones and subsequently propagating meridionally to equatorial latitudes. A 'fast' dominant mode and two slower modes are identified. We find that, at the magnetic equator, all the clearly identified modes of AGW interfere constructively and pass through to the opposite hemisphere with unchanged velocity. At F-region altitudes the 'fast' AGW has the largest amplitude, and when northward propagating and southward propagating modes interfere at the equator, the TID (as parameterised by the fractional change in the electron density at the F2 peak) increases in magnitude at the equator. The amplitude of the TID at the magnetic equator is increased compared to mid-latitudes in both upper and lower F-regions with a larger increase in the upper F-region. The ionospheric disturbance at the equator persists in the upper F-region for about 1 hour and in the lower F-region for 2.5 hours after the AGWs first interfere, and it is suggested that this is due to enhancements of the TID by slower AGW modes arriving later at the magnetic equator. The complex effects of the interplays of the TIDs generated in the equatorial plasmasphere are analysed by examining neutral and ion winds predicted by the model, and are demonstrated to be consequences of the forcing of the plasmasphere along the magnetic field lines by the neutral air pressure wave.

Search for Atmospheric Gravity Waves induced by the Eclipse of June 30, 1973

Nature ◽  
1973 ◽  
Vol 246 (5433) ◽  
pp. 412-413 ◽  
Author(s):  
J. E. BECKMAN ◽  
J. I. CLUCAS
Keyword(s):  
Gravity Waves ◽  
Atmospheric Gravity Waves ◽  
Atmospheric Gravity
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