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Poster (Scientific congresses and symposiums)
Anomalous OI-989 Å intensity profile: solving an old mystery.
Hubert, Benoît; Gérard, Jean-Claude; Shematovich, Valery I. et al.
2012AGU Fall Meeting
Editorial reviewed
 

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Keywords :
Thermosphere: composition and chemistry; Radiation: transmission and scattering; Thermosphere: energy deposition; Radiative processes
Abstract :
[en] Sounding rocket measurements conducted in 1988 under high solar activity conditions had revealed that the intensity of the thermospheric OI emission at 989 Å presents an anomalous vertical profile. Observation presents an intensity much higher than what can be expected compared with theoretical results including the photochemical sources of excited oxygen and the radiative transfer of the photons of the OI-989 sextuplet especially above the exobase. Attempts were conducted to clarify the discrepancy by including the non-thermal O(3P) population that appears around the exobase and higher, and that can scatter Doppler-shifted photons of the line profile farther from the rest wavelength. All attempts based on detail modeling of the photochemical processes and radiative transfer revealed unable to account for the discrepancy. Recently the FUV and EUV solar flux has been obtained at very high spectral resolution with the SOHO-SUMER instrument, revealing a significant solar oxygen emission at 989 Å, i.e. a source of photons that had never been accounted for before. In this study, we compute the radiative transfer of the OI-989 Å multiplet including the photochemical sources of excited oxygen, the scattering of incident solar photons and the effect of non-thermal atoms. We find a good agreement with the previous sounding rocket observation, solving the old mystery. We also compare the model simulations with the observations of the STP-78 satellite to better determine the relative importance of the various parameters at work in the radiative transfer of the OI-989 Å multiplet.
Disciplines :
Space science, astronomy & astrophysics
Author, co-author :
Hubert, Benoît  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Labo de physique atmosphérique et planétaire (LPAP)
Gérard, Jean-Claude  ;  Université de Liège - ULiège > Département d'astrophys., géophysique et océanographie (AGO) > Département d'astrophys., géophysique et océanographie (AGO)
Shematovich, Valery I.;  Russian Academy of Sciences, Moscow, Russian Federation > Institute of Astronomy
Bisikalo, Dmitry V.;  Russian Academy of Sciences, Moscow, Russian Federation > Institute of Astronomy
Chakrabarti, Supriya;  Boston University, Boston, MA, USA > Astronomy
Gladstone, Randall G.;  Southwest Research Institute, San Antonio, TX, United States
Language :
English
Title :
Anomalous OI-989 Å intensity profile: solving an old mystery.
Publication date :
06 December 2012
Event name :
AGU Fall Meeting
Event date :
03 - 07 December 2012
Audience :
International
Peer reviewed :
Editorial reviewed
Available on ORBi :
since 15 January 2013

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