Gravity waves near 300 km over the polar caps

Johnson, Francis S.; Hanson, W. B.; Hodges, R. R.; Coley, W. R.; Carignan, G. R.; Spencer, N. W.

doi:10.1029/95ja02858

Cited by 73 publications

(90 citation statements)

References 7 publications

(4 reference statements)

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“…It is easy to see that the wave propagates in reverse flight direction (leftwards in the plot). Almost all observed polar AGWs were propagating towards the dayside (Johnson et al, 1995;Fedorenko and Kryuchkov, 2011a). Note that the systematic phase shift between the density variation of different gases in Fig.…”

Section: Observational Signaturesmentioning

confidence: 88%

“…In the day sector the region of increased wave activity is bounded by the auroral oval, but in the night sector it can span down to lower geomagnetic latitudes. The dominant horizontal wavelength in the polar thermosphere is 500-600 km (Fedorenko and Kryuchkov, 2011a;Johnson et al, 1995). In the following subsections we briefly summarize the main features of polar AGWs as deduced primarily from DE2 measurements.…”

Section: Properties Of Polar Agwsmentioning

confidence: 99%

“…and the variations of v z are ahead of h by π/2 in the direction of propagation (Johnson et al, 1995). The vertical velocity v z was measured by the WATS experiment onboard DE2 .…”

Section: Observational Signaturesmentioning

confidence: 99%

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A dominant acoustic-gravity mode in the polar thermosphere

et al. 2015

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Abstract. The article presents a summary of the main findings of the systematic study of acoustic-gravity waves (AGWs) in the polar thermosphere. This study was based on the in situ measurements made by the Dynamics Explorer 2 (DE2) spacecraft late in its mission when it descended low enough (250-400 km). It was found out that AGWs in the polar thermosphere are observed within a narrow frequency band close to the Brunt-Väisälä frequency and with horizontal wavelengths about 500-600 km. The broadband spectrum of travelling ionospheric disturbance (TID) frequencies observed by radars is caused by the Doppler effect. The AGW amplitudes do not depend on the altitude, but grow almost linearly with the wind velocity. They propagate towards the wind.

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Section: Observational Signaturesmentioning

confidence: 88%

Section: Properties Of Polar Agwsmentioning

confidence: 99%

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A dominant acoustic-gravity mode in the polar thermosphere

et al. 2015

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“…Using data from Dynamics Explorer 2 satellite, Johnson et al [1995] reported quasisinusoidal patterns of vertical velocity of both ions and neutrals over the polar caps. Shiokawa et al [2003] discussed a simultaneous ground-satellite observation of a nighttime MSTID event using DMSP F15 satellite data and airglow images from ground-based observation.…”

Section: Introductionmentioning

confidence: 99%

First simultaneous observations of daytime MSTIDs over North America using GPS‐TEC and DEMETER satellite data

Onishi¹,

Tsugawa²,

Otsuka³

et al. 2009

Geophysical Research Letters

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[1] We present simultaneous observations of daytime medium-scale traveling ionospheric disturbances (MSTIDs) over North America, using measurements of the Total Electron Content (TEC) by the US GPS network and ionospheric plasma data from the DEMETER microsatellite. Several events show latitudinal variations of the plasma parameters at satellite altitude corresponding to the MSTID structures revealed on 2D TEC maps. In a case study with a very well defined MSTID, quasi periodic variations of the plasma density and of the ion velocity parallel to the Earth's magnetic field are observed along the satellite orbit that match the signature of the MSTID on the TEC maps. We believe it is the first simultaneous observation of parallel plasma motion in the topside ionosphere and propagating MSTID structures in the F-region. An initial analysis of this event is performed in the light of results from simple model of ionospheric disturbances associated with Atmospheric Gravity Waves (AGWs).

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“…Williams et al, 1988;Fukao et al, 1993), satellite (e.g. Johnson et al, 1995) and tomographic techniques (e.g. Pryse et al, 1995), and have cast light on the validity of theoretical and numerical models (e.g.…”

Section: Introductionmentioning

confidence: 99%

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

Moffett

1997

Ann Geophysicae

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Abstract.A global coupled thermosphere-ionosphereplasmasphere 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 identi®ed. We ®nd that, at the magnetic equator, all the clearly identi®ed 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 ®rst 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 e ects 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 ®eld lines by the neutral air pressure wave.

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Gravity waves near 300 km over the polar caps

Abstract: Abstract

Cited by 73 publications

References 7 publications

A dominant acoustic-gravity mode in the polar thermosphere

A dominant acoustic-gravity mode in the polar thermosphere

First simultaneous observations of daytime MSTIDs over North America using GPS‐TEC and DEMETER satellite data

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

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