scholarly journals Spectral variability in high frequency in sea level and atmospheric pressure on Buenos Aires Coast, Argentina

2017 ◽  
Vol 65 (1) ◽  
pp. 69-78 ◽  
Author(s):  
Iael Perez ◽  
Dragani Walter
Keyword(s):  
Gravity Waves ◽  
Atmospheric Pressure ◽  
Buenos Aires ◽  
Numerical Models ◽  
Spectral Energy ◽  
Spectral Variability ◽  
Atmospheric Gravity Wave ◽  
Atmospheric Gravity Waves ◽  
Atmospheric Gravity ◽  
Low Activity

Abstract There are some observational evidences which support that atmospheric gravity waves constitute an efficient forcing for meteorological tsunamis (meteotsunamis) along the coast of Buenos Aires, Argentina. Meteotsunamis and atmospheric gravity waves, which propagate simultaneously on the sea surface and the atmosphere, respectively, are typical examples of non-stationary geophysical signals. The variability of meteotsunamis and atmospheric gravity waves recorded at Mar del Plata was investigated in this paper. Results obtained in this work reinforce the idea of a cause (atmospheric gravity waves) effect (meteotsunami) relationship, because wavelet spectra obtained from both signals resulted quite similar. However, several very short episodes of mod-erate/low activity of atmospheric gravity waves were detected without detecting meteotsunami activity. On the other hand, it was found that atmospheric gravity wave spectral energy can appear in the wavelets as a single or multiple burst as relatively long and irregular events or as regular wave packets. Results obtained in this paper provide original spectral data about atmospheric gravity waves along the coast of Buenos Aires. This information is useful to be included in realistic numerical models in order to investigate the genesis of this complex atmosphere-ocean interaction.

scholarly journals A review of atmospheric gravity waves and travelling ionospheric disturbances: 1982-1995

1996 ◽  
Vol 14 (9) ◽  
pp. 917-940 ◽  
Author(s):  
K. Hocke ◽  
K. Schlegel
Keyword(s):  
Gravity Waves ◽  
Ionospheric Disturbances ◽  
Atmospheric Gravity Wave ◽  
Atmospheric Gravity Waves ◽  
Travelling Ionospheric Disturbances ◽  
The Past ◽  
Low Latitudes ◽  
Subsequent Propagation ◽  
Atmospheric Gravity ◽  
Inversion Techniques

Abstract. Recent investigations of atmospheric gravity waves (AGW) and travelling ionospheric disturbances (TID) in the Earth\\'s thermosphere and ionosphere are reviewed. In the past decade, the generation of gravity waves at high latitudes and their subsequent propagation to low latitudes have been studied by several global model simulations and coordinated observation campaigns such as the Worldwide Atmospheric Gravity-wave Study (WAGS), the results are presented in the first part of the review. The second part describes the progress towards understanding the AGW/TID characteristics. It points to the AGW/TID relationship which has been recently revealed with the aid of model-data comparisons and by the application of new inversion techniques. We describe the morphology and climatology of gravity waves and their ionospheric manifestations, TIDs, from numerous new observations.

Numerical Dispersion of Gravity Waves

2009 ◽  
Vol 137 (12) ◽  
pp. 4344-4354 ◽  
Author(s):  
Guido Schroeder ◽  
K. Heinke Schlünzen
Keyword(s):  
Gravity Waves ◽  
Numerical Models ◽  
Propagation Speed ◽  
Numerical Dispersion ◽  
Nonuniform Grid ◽  
Grid Spacing ◽  
Atmospheric Gravity Waves ◽  
Fine Grid ◽  
Advection Schemes ◽  
Atmospheric Gravity

Abstract When atmospheric gravity waves are simulated in numerical models, they are not only dispersive for physical but also for numerical reasons. Their wave properties (e.g., damping or propagation speed and direction) can depend on grid spacing as well as on the numerical schemes. In this work numerical dispersion relations for atmospheric gravity waves are theoretically derived as well as experimentally measured using the anelastic Mesoscale Transport and Stream model (METRAS). Both the theoretical solution and the numerical model show a retardation of gravity waves with decreasing grid resolution. Furthermore, the influence of a Shapiro seven-point filter is analyzed. The Shapiro seven-point filter causes damping of the shorter waves. Therefore, shorter waves can better be simulated without the seven-point filter. The influence of different advection schemes is analyzed by prescribing a background wind. A first-order upstream scheme and second- and third-order flux integrated essentially nonoscillatory (FIENO) schemes are used. As expected, the damping is the smaller the higher the order of the scheme. The numerical dispersion has severe consequences, when nonuniform grid spacing is used. Waves moving from the fine grid to the coarse are reflected because of numerical dispersion if they are only poorly resolved on the coarse grid. In tests with different refinement factors and wave lengths the reflection is found to be the larger the greater the refinement factor. The results show that refinement factors larger than 3 should not be used with nonuniform grid spacing or two-way nested grids.

scholarly journals Atmospheric Gravity Wave Science in the Polar Regions

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Tracy Moffat-Griffin ◽  
Mike Taylor ◽  
Takuji Nakamura ◽  
Damian Murphy ◽  
Jose Bageston ◽  
...  
Keyword(s):  
Gravity Wave ◽  
Gravity Waves ◽  
Polar Regions ◽  
Special Issue ◽  
Atmospheric Gravity Wave ◽  
Atmospheric Gravity Waves ◽  
Global Circulation ◽  
Atmospheric Gravity

A joint special issue explores the potential of collaboration to help understand atmospheric gravity waves in the Polar Regions and their effect on global circulation.

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.

scholarly journals EFEK GELOMBANG TSUNAMI ACEH 2004 PADA GANGGUAN IONOSFER BERGERAK SKALA MENENGAH DARI PENGAMATAN JARINGAN GPS SUMATRA

2019 ◽  
Vol 16 (2) ◽  
pp. 130
Author(s):  
Asnawi Husin ◽  
Buldan Muslim
Keyword(s):  
Gravity Waves ◽  
Ionospheric Disturbance ◽  
Volcanic Eruptions ◽  
Electron Content ◽  
Atmospheric Gravity Wave ◽  
Atmospheric Gravity Waves ◽  
Total Electron ◽  
Medium Scale ◽  
Pierce Point ◽  
Atmospheric Gravity

Medium Scale Travelling Ionospheric Disturbance (MSTID), thought to be manifestation of atmospheric gravity wave (AGW) in the ionospheric altitude that propagates horizontally and effects on in the electron density structure of ionosphere. These atmospheric gravity waves sourced  from lower atmospheric activities such as typhoons, volcanic eruptions and tsunamis. Wave energy by its coupling induction process can travel to the ionosphere region. It has been understood that the TID's wave structure have an impact on the propagation of radio waves in the ionosphere so that it will affect the performance of navigation satellite-based positioning measurements. Based on Aceh tsunami in December 2004, this study aimed to investigation of the induction of atmospheric gravity waves in the ionosphere using total electron content (TEC) data from the Sumatra GPS network (Sumatra GPS Array, SUGAR). The detection technique of TEC changes due to AGW induction with a filter to separate medium scale disturbance at the ionospheric pierce point at an altitude of 350 km (IPP, Ionospheric Pierce Point). The results show the horizontal wavelength of a medium-scale TID around 180 ± 12 Km with a velocities of around 376 ± 9 ms-1. Based on two-dimensional map, the TID moves to the southeast.

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.

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