Thermosphere dynamics: Contributions from the first 5 years of the Dynamics Explorer Program

Killeen, T. L.; Roble, R. G.

doi:10.1029/rg026i002p00329

Cited by 138 publications

(96 citation statements)

References 114 publications

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“…It shows the strong dependence of the thermospheric wind at F-region heights (∼400 km) on the IMF conditions. These patterns confirm previous findings based on early satellite data in the 1980s (e.g., Killeen and Roble, 1988;Killeen et al, 1995), but can now rest upon a much broader statistical base due to the good coverage of the CHAMP data. This allowed for the first time a systematic analysis of the solar wind and IMF dependences with respect to the thermospheric vorticity pattern at high geomagnetic latitudes.…”

Section: Discussionsupporting

confidence: 80%

“…It was noted already in earlier studies, that the anticyclonic dusk side vortex of the average thermospheric circulation is almost invariably stronger than the cyclonic vortex associated with the dawn side ion convection cell (Killeen and Roble, 1988). These observations were accompanied by comprehensive theoretical-numerical studies (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…The comprehensive CHAMP data set and the novel methodology of its data analysis as elaborated in Sect. 2 allow detailed studies of the high-latitude thermospheric wind behaviour at Fregion height like those of the DE-2 mission about two solar cycles earlier (Killeen and Roble, 1988;Killeen et al, 1995;Thayer and Killeen, 1991). The novelty of our study, based on well-founded statistics, consists in the first systematic analysis of the thermospheric vorticity in polar regions of both hemispheres in dependence on the IMF orientation, which is presented in Sect.…”

Section: Introductionmentioning

confidence: 99%

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Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence

Förster

Haaland

Doornbos³

2011

Ann. Geophys.

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Abstract. Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both polar regions are used to deduce statistical neutral wind vorticity distributions and were analyzed in their dependence on the Interplanetary Magnetic Field (IMF). The average pattern confirms the large duskside anticyclonic vortex seen in the average wind pattern and reveals a cyclonic vorticity on the dawnside, which is almost equal in magnitude to the duskside minimum. The outer shape of the vorticity pattern agrees approximately with the outer boundary of region-1 currents in the well-known average current distributions of Iijima and Potemra (1976). The IMF dependence of the vorticity pattern resembles the characteristic FAC and ionospheric plasma drift pattern known from various statistical studies obtained under the same sorting conditions.

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Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence

Förster

Haaland

Doornbos³

2011

Ann. Geophys.

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“…Observations from the DE-2 spacecraft (Killeen and Roble 1988) and complementary theory and modeling efforts are major contributors to our current level of knowledge. Much of the research in this context was devoted to an understanding of the relative importance of the EUVdriven circulation, effects induced by Joule and particle heating, and that part of the circulation driven by momentum transfer from the convecting ions (e.g., Killeen and Roble 1988;Killeen et al 1992;Killeen 1991, 1993). Observations in combination with thermosphere-ionosphere general circulation models have been used to elucidate the morphology and physics, often decomposing the flow field into nondivergent (irrotational) and divergent (rotational) components and examining their relative behaviors and influences.…”

Section: Polar-auroral Circulationmentioning

confidence: 99%

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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“…The most extensive data set about the behavior of the thermosphere and ionosphere in the northern and southern polar caps has been obtained by the Dynamics Explorer satellites (Killeen and Roble, 1988). These data have been analyzed by many authors, including Rees et al (1986) and Roble et al (1987Roble et al ( , 1988a using their thermospheric general circulation models.…”

Section: Comparison With the Observationsmentioning

confidence: 99%

Seasonal effects in the ionosphere-thermosphere response to the precipitation and field-aligned current variations in the cusp region

Namgaladze¹,

Volkov²

1998

Ann Geophysicae

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Abstract. The seasonal e ects in the thermosphere and ionosphere responses to the precipitating electron¯ux and ®eld-aligned current variations, of the order of an hour in duration, in the summer and winter cusp regions have been investigated using the global numerical model of the Earth's upper atmosphere. Two variants of the calculations have been performed both for the IMF B y < 0. In the ®rst variant, the model input data for the summer and winter precipitating¯uxes and ®eld-aligned currents have been taken as geomagnetically symmetric and equal to those used earlier in the calculations for the equinoctial conditions. It has been found that both ionospheric and thermospheric disturbances are more intensive in the winter cusp region due to the lower conductivity of the winter polar cap ionosphere and correspondingly larger electric ®eld variations leading to the larger Joule heating e ects in the ion and neutral gas temperature, ion drag e ects in the thermospheric winds and ion drift e ects in the F2-region electron concentration. In the second variant, the calculations have been performed for the events of 28±29 January, 1992 when precipitations were weaker but the magnetospheric convection was stronger than in the ®rst variant. Geomagnetically asymmetric input data for the summer and winter precipitating¯uxes and ®eld-aligned currents have been taken from the patterns derived by combining data obtained from the satellite, radar and ground magnetometer observations for these events. Calculated patterns of the ionospheric convection and thermospheric circulation have been compared with observations and it has been established that calculated patterns of the ionospheric convection for both winter and summer hemispheres are in a good agreement with the observations. Calculated patterns of the thermospheric circulation are in a good agreement with the average circulation for the Southern (summer) Hemisphere obtained from DE-2 data for IMF B y < 0 but for the Northern (winter) Hemisphere there is a disagreement at high latitudes in the afternoon sector of the cusp region. At the same time, the model results for this sector agree with other DE-2 data and with the ground-based FPI data. All ionospheric and thermospheric disturbances in the second variant of the calculations are more intensive in the winter cusp region in comparison with the summer one and this seasonal di erence is larger than in the ®rst variant of the calculations, especially in the electron density and all temperature variations. The means that the seasonal e ects in the cusp region are stronger in the thermospheric and ionospheric responses to the FAC variations than to the precipitation disturbances.

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Thermosphere dynamics: Contributions from the first 5 years of the Dynamics Explorer Program

Cited by 138 publications

References 114 publications

Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence

Thermospheric vorticity at high geomagnetic latitudes from CHAMP data and its IMF dependence

Dynamics of the Thermosphere

Seasonal effects in the ionosphere-thermosphere response to the precipitation and field-aligned current variations in the cusp region

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