Evidence of ENA precipitation in the EUV dayglow

Stephan, A. W.; Chakrabarti, Supriya; Cotton, Daniel M.

doi:10.1029/2000gl000040

Cited by 13 publications

(12 citation statements)

References 23 publications

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“…This is in good agreement with the conjecture of Stephan et al [2000] that this emission is caused by precipitating oxygen ENAs.…”

Section: May 11 2002 Stormsupporting

confidence: 81%

“…It is the general consensus of these authors that the observed enhancements are due to precipitation of energetic neutral atoms (ENA) originating in the ring current. Indeed Stephan et al [2000] has shown that various emission features exhibit a significant negative correlation with the Dst index, which is driven primarily by the strength of the ring current. Several mechanisms for this emission enhancement have been proposed, although a detailed description of the chemical and kinetic processes involved has yet to be established.…”

Section: Introductionmentioning

confidence: 99%

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Storm‐time enhancement of mid‐latitude ultraviolet emissions due to energetic neutral atom precipitation

Demajistre

Brandt

Immel

et al. 2005

Geophysical Research Letters

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[1] In this work we present a direct connection between Energetic Neutral Atom (ENA) precipitation and enhanced ultraviolet emissions from the mid-latitude thermosphere during times of geomagnetic disturbance. Data from the IMAGE/HENA instrument provides information about ENA emission from the ring current, the IMAGE/FUV instrument shows the temporal response of the ultraviolet airglow, and data from TIMED/GUVI is used to infer the vertical distribution of the airglow enhancement. We find that the airglow signature is well correlated with energetic atom precipitation. The ultraviolet emission has a maximum above 120 km tangent altitude and is dominated by OI 135.6 nm emission. The relative brightness of 135.6 nm emission and OI 130.4 nm radiance suggest a lack of an electron cascade. Citation: DeMajistre, R., P. Brandt, T. J.

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“…This is in good agreement with the conjecture of Stephan et al [2000] that this emission is caused by precipitating oxygen ENAs.…”

Section: May 11 2002 Stormsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Storm‐time enhancement of mid‐latitude ultraviolet emissions due to energetic neutral atom precipitation

Demajistre

Brandt

Immel

et al. 2005

Geophysical Research Letters

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“…Some of the deposited energy from the plasmasphere and the magnetosphere can be carried back to the exosphere by the upward flux of the hydrogen atoms, leading to large satellite populations and an enhanced escape rate. There is some evidence indicating a significant influence of energetic neutral particle precipitation from the ring current on the dayglow at low and mid-latitudes (<30° geomagnetic latitude)2930. Those works show that the low-latitude dayglow emissions, including the OII 83.4, OI 98.9 and 130.4 nm, as well as the H-Ly α emissions observed from the STP 78–1 satellite at 600 km altitude, are brightened during geomagnetically active times compared with quiet times.…”

Section: Resultsmentioning

confidence: 99%

Non-thermal hydrogen atoms in the terrestrial upper thermosphere

Qin

Waldrop

2016

Nat Commun

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Model predictions of the distribution and dynamical transport of hydrogen atoms in the terrestrial atmosphere have long-standing discrepancies with ultraviolet remote sensing measurements, indicating likely deficiencies in conventional theories regarding this crucial atmospheric constituent. Here we report the existence of non-thermal hydrogen atoms that are much hotter than the ambient oxygen atoms in the upper thermosphere. Analysis of satellite measurements indicates that the upper thermospheric hydrogen temperature, more precisely the mean kinetic energy of the atomic hydrogen population, increases significantly with declining solar activity, contrary to contemporary understanding of thermospheric behaviour. The existence of hot hydrogen atoms in the upper thermosphere, which is the key to reconciling model predictions and observations, is likely a consequence of low atomic oxygen density leading to incomplete collisional thermalization of the hydrogen population following its kinetic energization through interactions with hot atomic or ionized constituents in the ionosphere, plasmasphere or magnetosphere.

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“…Although we cannot quantify the above‐discussed uncertainties due to insufficient data constraints, we note that our results are consistent with previously reported observations. For example, Stephan et al [] showed a storm time brightness decrease in the dayside Ly α airglow emission as measured in the near‐zenith direction by the STP 78‐1 satellite in low Earth orbit at 600 km. In additional simulations not shown here, we successfully reproduced these observations by modeling upward viewing Ly α measurements from a 600 km vantage using our estimated quiet time and storm time H density profiles.…”

Section: Storm‐driven H Redistribution In the Terrestrial Atmospherementioning

confidence: 99%

“…Over the past few decades, it has been well established that geomagnetic storms can significantly affect the near-Earth space environment, leading to enhancement of ionospheric plasma densities [Foster and Rideout, 2005;Heelis et al, 2009;Immel and Mannucci, 2013], compression of the plasmasphere [Spasojevic et al, 2003;Huba and Krall, 2013], and heating of the thermosphere [Fuller-Rowell et al, 1994;Burns et al, 1995;Lei et al, 2010]. Variations of the atmospheric temperature, composition, and particle densities during storms can manifest as evident changes in the observations of thermospheric UV emissions [Stephan et al, 2000;Zhang et al, 2006] and exospheric H emissions [Kerr et al, 2001;Bailey and Gruntman, 2013;Kuwabara et al, 2017;Zoennchen et al, 2017].…”

Section: Introductionmentioning

confidence: 99%

Redistribution of H atoms in the upper atmosphere during geomagnetic storms

2017

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Geocoronal H emission data acquired by NASA's Thermosphere Ionosphere Mesosphere Energetics and Dynamics mission are analyzed to quantify the H density distribution over the entire magnetosphere‐ionosphere‐thermosphere region in order to investigate the response of the atmospheric system as a whole to geomagnetic storms. It is shown that at low and middle latitudes the H density averaged over storm times in the thermosphere‐exosphere transition region decreases by ∼30%, while the H density at exospheric altitudes above ∼1–2 RE increases by up to ∼40% relative to quiet times. We postulate that enhanced ion‐neutral charge exchange in the topside ionosphere and inner plasmasphere is the primary driver of the observed H redistribution. Specifically, charge exchange reactions between H atoms and ionospheric/plasmaspheric O+ lead to direct H loss, while those between thermal H and H+ yield kinetically energized H atoms which populate gravitationally bound satellite orbits. The resulting H density enhancements in the outer exosphere would enhance the charge exchange rates in the ring current and the associated energetic neutral atom production. Regardless of the underlying mechanisms, H redistribution should be considered as an important process in the study of storm time atmospheric evolution, and the resultant changes in the geocoronal H emissions potentially could be used to monitor geomagnetic storms.

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Evidence of ENA precipitation in the EUV dayglow

Abstract: Abstract.Observations

Cited by 13 publications

References 23 publications

Storm‐time enhancement of mid‐latitude ultraviolet emissions due to energetic neutral atom precipitation

Storm‐time enhancement of mid‐latitude ultraviolet emissions due to energetic neutral atom precipitation

Non-thermal hydrogen atoms in the terrestrial upper thermosphere

Redistribution of H atoms in the upper atmosphere during geomagnetic storms

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