On the contribution of thermal excitation to the total 630.0 nm emissions in the northern cusp ionosphere
Permanent lenke
https://hdl.handle.net/10037/11421Dato
2017-01-25Type
Journal articleTidsskriftartikkel
Peer reviewed
Sammendrag
Direct impact excitation by precipitating electrons is believed to be the main source of
630.0 nm emissions in the cusp ionosphere. However, this paper investigates a different source, 630.0
emissions caused by thermally excited atomic oxygen O(1D) when high electron temperature prevail in
the cusp. On 22 January 2012 and 14 January 2013, the European Incoherent Scatter Scientific Association
(EISCAT) radar on Svalbard measured electron temperature enhancements exceeding 3000 K near
magnetic noon in the cusp ionosphere over Svalbard. The electron temperature enhancements
corresponded to electron density enhancements exceeding 1011 m−3 accompanied by intense 630.0 nm
emissions in a field of view common to both the EISCAT Svalbard radar and a meridian scanning
photometer. This offered an excellent opportunity to investigate the role of thermally excited O(1D)
630.0 nm emissions in the cusp ionosphere. The thermal component was derived from the EISCAT Radar
measurements and compared with optical data. For both events the calculated thermal component had
a correlation coefficient greater than 0.8 to the total observed 630.0 nm intensity which contains both
thermal and particle impact components. Despite fairly constant solar wind, the calculated thermal
component intensity fluctuated possibly due to dayside transients in the aurora.
Beskrivelse
Source at http://dx.doi.org/10.1002/2016JA023366