Dayside enhancements of thermospheric O/N<sub>2</sub> following magnetic storm onset

Immel, T. J.; Crowley, G.; Craven, J. D.; Roble, R. G.

doi:10.1029/2000ja000096

Cited by 68 publications

(63 citation statements)

References 37 publications

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“…It is widely believed (e.g., Tsugawa et al, 2006;Immel et al, 2001) that the storm induced meridional winds result in changes in chemical composition signified by thermospheric [O/N 2 ] ratio. In order to confirm our inferences regarding TADs, we have looked for data from the GUVI on board the TIMED satellite which provides the ratio in a latitudelongitude grid of 1.75 • × 1.75 • .…”

Section: Variation Of Thermospheric [O/n 2 ] Ratiomentioning

confidence: 99%

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Sharma¹,

Galav²,

Dashora

et al. 2011

Ann. Geophys.

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Abstract.Response of low latitude ionosphere to the geomagnetic storm of 15 May 2005 has been studied using total electron content (TEC) data, obtained from three GPS stations namely, Yibal, Udaipur and Kunming situated near the northern crest of equatorial ionization anomaly at different longitudes. Solar wind parameters, north-south component of the interplanetary magnetic field (IMF B z ) and AE index data have been used to infer the strength of the geomagnetic storm. A large value of eastward interplanetary electric field at 06:15 UT, during the time of maximum southward IMF B z has been used to infer the transmission of an eastward prompt penetration electric field (PPEF) which resulted in a peak in TEC at 07:45 UT due to the local uplift of plasma in the low latitudes near the anomaly crest over a wide range of longitudes. Wave-like modulations superposed over the second enhancement in TEC between 09:15 UT to 10:30 UT have been observed at all the three stations. The second enhancement in TEC along with the modulations of up to 5 TECU have been attributed to the combined effect of super plasma fountain and traveling atmospheric disturbances (TAD). Observed large enhancements in TEC are a cause of concern for satellite based navigation and ground positioning. Increased [O/N 2 ] ratio between 09:15 UT to 10:15 UT when modulations in TEC have been also observed, confirms the presence of TADs over a wide range of longitudes.

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Section: Variation Of Thermospheric [O/n 2 ] Ratiomentioning

confidence: 99%

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Sharma¹,

Galav²,

Dashora

et al. 2011

Ann. Geophys.

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“…Killeen et al, 1984;Hajkowicz, 1990). Immel et al (2001) simulated large-scale TADS launched simultaneously in conjugate auroral zones, which coalesced near the equator. Prolss (1993) indicated that, at low latitudes, the energy dissipation of the two TADs launched in both hemispheres causes an increase in the upper atmosphere temperature and in the gas densities.…”

Section: Wave-like Responsementioning

confidence: 99%

Response of the equatorial and low-latitude ionosphere during the space weather events of April 2002

et al. 2004

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The two CADIs are part of a new network being established in a collaborative program between UNIVAP and CEULP/ULBRA, to study the equatorial and low-latitude ionospheric regions in Brazil. In this paper we present and discuss the effects of the space weather events during 17-20 April 2002, as evidenced by the ionospheric parameter changes from simultaneous observations at São José dos Campos and Palmas. A comparison of the observed ionospheric parameters (h F , hpF 2 and f oF 2) at the two stations, separated only by about 1460 km, shows both similarities and differences associated with the geomagnetic disturbances. Also, a comparison of the observed F -region parameters with the ASPEN-TIMEGCM model results is presented. The model results show reasonable agreement during the quiet period of observations, but some discrepancies have been observed during the geomagnetic disturbances.

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“…Mikhailov et al (1995) had analyzed the AC-C and ESRO-4 neutral composition data for the 24-26 January 1974 storm and suggested that the daytime positive storm is due to the storm-induced thermospheric winds, not the changes of the neutral compositions. Other workers (e.g., Field and Rishbeth, 1997;Immel et al, 2001) also suggested that the positive storms are caused by the neutral composition perturbation. This case study provides evidence of the composition effect for the daytime positive phase at middle latitude, in addition to dynamical effects of neutral winds and electric fields.…”

Section: Discussionmentioning

confidence: 98%

“…The causes for positive storm effects are more complicated. The mostly suggested causes may be the F 2 layer uplifting due to thermospheric winds and electric fields or traveling atmospheric disturbances (TADs) (Prölss, 1993(Prölss, , 1995Werner et al, 1999), and also changes in neutral compositions (e.g., Field and Rishbeth, 1997;Field et al, 1998;Immel et al, 2001). Therefore, mechanisms for the magnetic storm, especially for the positive storm, are issues not quite understood, and direct measurements are very important for any further investigations.…”

Section: Introductionmentioning

confidence: 99%

Modeling investigation of ionospheric storm effects over Millstone Hill during August 4–5, 1992

et al. 2014

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We examine the physical mechanism of the negative and positive storm at middle latitude in August 1992, based on incoherent scatter radar (ISR) observations over Millstone Hill (42.6 • N, 288.5• E) and a first-principles ionospheric model. The exospheric temperature T ex , thermospheric composition and neutral winds, inferred from the ion temperature T i profile using the ion energy balance calculation (e.g., Bauer et al., 1970;Oliver, 1979) and from the electron density N e profile using an ISR data assimilation method (Zhang et al., 2001(Zhang et al., , 2002, are employed to investigate the storm effects. The derived thermospheric information shows that the negative phase on August 5 is attributed to both the large poleward wind and the reduced [O] ] ratio at F 2 -layer. For the daytime positive storm on August 4, the thermospheric composition perturbation, in addition to the enhanced equatorward wind, plays a significant role. This study also suggests that the data assimilation technique can provide useful information to understand some physical mechanisms of the ionospheric storm when direct experimental data are not available.

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Dayside enhancements of thermospheric O/N₂ following magnetic storm onset

Cited by 68 publications

References 37 publications

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Response of the equatorial and low-latitude ionosphere during the space weather events of April 2002

Modeling investigation of ionospheric storm effects over Millstone Hill during August 4–5, 1992

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Dayside enhancements of thermospheric O/N2 following magnetic storm onset

Cited by 68 publications

References 37 publications

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Longitudinal study of the ionospheric response to the geomagnetic storm of 15 May 2005 and manifestation of TADs

Response of the equatorial and low-latitude ionosphere during the space weather events of April 2002

Modeling investigation of ionospheric storm effects over Millstone Hill during August 4–5, 1992

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Dayside enhancements of thermospheric O/N₂ following magnetic storm onset