Large-Scale Waves in the Thermosphere Observed by the AE-C Satellite

Gross, S. H.; Reber, C. A.; Huang, Fang

doi:10.1109/tgrs.1984.350635

Cited by 22 publications

(16 citation statements)

References 47 publications

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“…Perturbations with horizontal scales of ∼5–10° latitude and amplitudes of order 5–20% are clearly evident. The presence of wave‐like structures in thermosphere neutral density measurements is not new [see, e.g., Gross et al , 1984; Hoegy et al , 1979; Hedin and Mayr , 1987; Prölss , 1980; Forbes et al , 1995]. Owing to poor time resolution of the measurements at a given latitude (i.e., the orbital period, or about 90 min), unambiguous interpretation of the propagation characteristics of wave‐like features in satellite measurements is difficult.…”

Section: Resultsmentioning

confidence: 99%

Thermosphere density variations due to the 15–24 April 2002 solar events from CHAMP/STAR accelerometer measurements

Forbes

Bruinsma

et al. 2005

J. Geophys. Res.

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[1] Thermosphere densities near 410 km altitude between ±87°latitude and near 0430 and 1530 local time from the accelerometer experiment on the CHAMP satellite are used to elucidate the response to three coronal mass ejections occurring on 17, 19, and 21 April 2002. Comparisons of the global responses with the NRLMSISE00 empirical model and the NCAR TIEGCM are performed and interpreted. An enhanced daytime response in comparison to TIEGCM on 17 April is found that is suggestive of preconditioning of the atmosphere due to enhanced solar EUV fluxes maximizing on 13 April. Out of several solar wind parameters and geophysical indices that were examined, the highest correlation with thermosphere densities occurred with respect to the magnitude of the interplanetary magnetic field as measured by the ACE spacecraft. Wave-like structures with scales ranging from 100s to 1000s of kilometers are also revealed in the CHAMP data. These structures are primarily a nighttime phenomena, and the associated total variance is correlated with magnetic activity throughout the 15-24 April 2002 period. The NCAR TIEGCM was utilized to provide the basis for interpreting the equatorward propagation of large-scale traveling atmospheric disturbance (TADs). Following a sudden increase in magnetic activity and high-latitude heating, TADs were launched from both hemispheres, traveled toward the equator with phase speeds of order 800 m s À1 , constructively interfered near the equator to produce a total density perturbation of $20%, and then passed through each other and into the opposite hemisphere. Perspectives on future applications of CHAMP accelerometer data to elucidate magnetic storm-related perturbations of the thermosphere are outlined.

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Section: Resultsmentioning

confidence: 99%

Thermosphere density variations due to the 15–24 April 2002 solar events from CHAMP/STAR accelerometer measurements

Forbes

Bruinsma

et al. 2005

J. Geophys. Res.

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“…Studies by e.g. Williams et al (1988) have shown that there can be a periodicity to the source mechanism to produce an AGW wave-train, and such a wave-train could further prolong the decay of the lower F-region equatorial disturbance as suggested by Gross et al (1984). …”

Section: Discussionmentioning

confidence: 98%

“…Large-scale ionospheric disturbances propagating equatorwards and associated with low-latitude aurorae have been studied by Igarashi et al (1991). Satellite measurements (Gross et al, 1984) reveal the presence of standing waves in the equatorial ionosphere,`p ossibly as a result of interference between waves from two sources (both auroral regions) '' and Hajkowicz (1991) has shown that geomagnetic activity can produce conjugate AGWs travelling from both auroral zones. Fesen et al, (1989) used separate thermospheric and ionospheric models to examine the e ects of a geomagnetic storm and showed that the equatorial disturbances observed were the result of neutral winds and AGWs.…”

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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“…These models show that the neutral atmosphere response is dependent upon a complexity of interdependent processes involving electrodynamics, mutual coupling between the neutral and plasma species, chemistry and radiative cooling. Nevertheless, simpler models have been used to elucidate the wavelike aspects of the thermosphere response to impulsive heating (e.g., Richmond and Matsushita 1975;Richmond 1979;Brinkman et al 1992;Mayr et al 1990), and are able to explain some of the salient features of wave-like structures seen in satellite data (e.g., Gross et al 1984;Forbes et al , 2005Bruinsma et al 2006). Our current general perception of the magnetic storm response of the thermosphere based upon these and other modeling efforts noted below, as well as recent observations, is now described.…”

Section: Global Response To Geomagnetic Disturbancesmentioning

confidence: 91%

Dynamics of the Thermosphere

Forbes

2007

Journal of the Meteorological Society of Japan

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Major advances in our understanding of the dynamics of Earth's thermosphere (A 90-500 km) during the past 25 years are reviewed. Since the thermosphere is primarily an externally-forced system, a broad overview of the energy input, conversion and transport mechanisms in the ionosphere-thermosphere system is first provided. This serves as background and context for the non-specialist. Then, several broad areas of progress are in turn discussed in some detail: (i) the role of solar thermal tides in imposing significant longitudinal variability in the lower thermosphere (A 100-150 km), and affecting the zonal mean circulation at these altitudes; (ii) the zonal mean circulation of the thermosphere, the changes in O and N 2 relative densities that accompany it, and the competing roles of solar radiative heating and Joule (ohmic) heating in determining the overall structure of this circulation; (iii) polar and auroral thermosphere dynamics, and connections to relevant magnetosphere and ionosphere processes; and (iv) the global response to geomagnetic disturbances, i.e., relatively sudden injections of energy and momentum from the magnetosphere. The paper concludes with a personal assessment of future research directions and scientific questions that remain to be addressed in forthcoming decades.

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Large-Scale Waves in the Thermosphere Observed by the AE-C Satellite

Cited by 22 publications

References 47 publications

Thermosphere density variations due to the 15–24 April 2002 solar events from CHAMP/STAR accelerometer measurements

Thermosphere density variations due to the 15–24 April 2002 solar events from CHAMP/STAR accelerometer measurements

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

Dynamics of the Thermosphere

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