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Ionospheric composition: The seasonal anomaly explainedThe main photochemical processes of the ionosphere are reanalyzed in the light of laboratory measurements of rate coefficients, using the Atmosphere Explorer data. Major changes to the chemistry include the transfer of nearly all metastable 0(+) ions to N2(+) via charge exchange with N2. The N2(+) ions become vibrationally excited by resonant fluorescence of solar near UV and near infrared radiation, leading to a return transfer of N2(+) ionization to 0(+) by charge exchange or vibrationally excited N2(+) with atomic oxygen. With this chemistry the seasonal variations in the peak electron densities are then shown to be caused primarily by anomalous seasonal variations in neutral composition. The required neutral composition variations are empirically produced by the MSIS model atmosphere. The circulation derived from recent 3D models of the global thermosphere qualitatively accounts for the seasonal variations in neutral composition predicted by the MSIS model. In addition to the composition effect, vibrationally excited N2 is found to contribute a 20% effect to the anomalous seasonal behavior at solar maximum.
Document ID
19810014990
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Torr, D. G.
(Utah State Univ. Logan, UT, United States)
Richards, P. G.
(Utah State Univ. Logan, UT, United States)
Torr, M. R.
(National Inst. for Telecommunications Research Johannesburg, South Africa)
Date Acquired
August 11, 2013
Publication Date
February 1, 1981
Publication Information
Publication: AGARD The Phys. Basis of the Ionosphere in the Solar-Terrest. System
Subject Category
Geophysics
Accession Number
81N23523
Funding Number(s)
CONTRACT_GRANT: NSF ATM-80-05088
CONTRACT_GRANT: NAS5-24331
Distribution Limits
Public
Copyright
Other
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