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| Titel |
Dayside 630.0 nm emissions due to thermally excited O(1D) in the cusp region ionosphere over Longyearbyen, Svalbard |
| VerfasserIn |
Norah Kaggwa Kwagala, Kjellmar Oksavik, Dag A. Lorentzen, Herbert C. Carlson |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250105796
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| Publikation (Nr.) |
 EGU/EGU2015-5373.pdf |
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| Zusammenfassung |
| In this paper we investigate the 630.0 nm emissions caused by thermally excited O(1D)
during extreme electron temperatures in the cusp region ionosphere and also provide their
characteristics. Particle precipitation is usually the main source of optical emissions.
However, recent research has acknowledged thermal excitation of O(1D) as an additional
source of 630.0 nm emissions. In this study we investigate the time, altitude and
conditions during which these emissions are most likely to occur. A combination of
formulae from Mantas and Carlson [1991] and Carlson et al. [2013] are used to
calculate the altitude discriminated and line-of-sight integrated thermally excited
O(1D) 630.0 nm intensity, where electron temperature and electron density from the
European Incoherent Scatter Scientific Association (EISCAT) stationary 42 m radar at
Svalbard, and atomic oxygen density from the United States Naval Research Laboratory
Mass Spectrometer and Incoherent Scatter Radar 2000 model (NRLMSISE-00) are
used as the primary input parameters. The calculated results of 630.0 nm are then
compared with observed 630.0 nm emissions from the Meridian Scanning Photometer
(MSP) at Kjell Henriksen Observatory (KHO). The days used in this study were
selected on the basis of high electron temperature and high electron density as well as
availabilty of optical data. This study shows that the thermally excited O(1D) emissions
mainly occurs during magnetic noon (11:00 - 13:00 MLT) at altitudes of 350-450
km when electron temperatures exceed 3000 K and electron density exceeds 1011
m-3.
References
Mantas,G. P., and H. C. Carlson (1991), Reexamination of the O(3P-1D) excitation rate by
thermal electron impact, Geophys. Res. Lett., 18(2), 159-162.
Carlson, H. C., K. Oksavik and J. Moen (2013), Thermally excited 630.0 nm O(1D) emission
in the cusp: A frequent high-altitude transient signature, J. Geophys. Res. Space Physics, 118,
1-11. |
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