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Titel |
Thermospheric neutral temperatures derived from charge-exchange produced N2+ Meinel (1,0) rotational distributions |
VerfasserIn |
C. K. Mutiso, M. D. Zettergren, J. M. Hughes, G. G. Sivjee |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
0992-7689
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Digitales Dokument |
URL |
Erschienen |
In: Annales Geophysicae ; 31, no. 3 ; Nr. 31, no. 3 (2013-03-12), S.463-471 |
Datensatznummer |
250019007
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Publikation (Nr.) |
copernicus.org/angeo-31-463-2013.pdf |
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Zusammenfassung |
Thermalized rotational distributions of neutral and ionized N2
and O2 have long been used to determine neutral temperatures (Tn)
during auroral conditions. In both bright E-region (≲150 km)
auroras, and in higher-altitude auroras, spectral distributions of molecular
emissions employed to determine Tn in the E-region cannot likewise be used
to obtain Tn in the F-region. Nevertheless, charge-exchange reactions
between high-altitude (≳130 km) species provide an exception to this
situation. In particular, the charge-exchange reaction O+(2D) + N2(X) → N+2(A2Πu, ν' = 1 + O(3P)
yields thermalized N2+ Meinel (1,0) emissions, which, albeit weak, can be
used to derive neutral temperatures at altitudes of ~130 km and higher.
In this work, we present N2+ Meinel (1,0) rotational temperatures and
brightnesses obtained at Svalbard, Norway, during various auroral conditions.
We calculate Tn at thermospheric altitudes of 130–180 km from
thermalized rotational populations of N2+ Meinel (1,0); these emissions
are excited by soft electron (≲1 keV) impact and charge-exchange
reactions. We model the contributions of the respective excitation
mechanisms, and compare derived brightnesses to observations. The agreement
between the two is good. Emission heights obtained from optical data,
modeling, and ISR data are consistent. Obtaining thermospheric Tn from
charge-exchange excited N2+ Meinel (1,0) emissions provides an additional
means of remotely sensing the neutral atmosphere, although certain limiting
conditions are necessary. These include precipitation of low-energy
electrons, and a non-sunlit emitting layer. |
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