High-latitude HF-induced airglow displaced equatorwards of the pump beam

Citation
Mj. Kosch et al., High-latitude HF-induced airglow displaced equatorwards of the pump beam, GEOPHYS R L, 27(17), 2000, pp. 2817-2820
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
0094-8276 → ACNP
Volume
27
Issue
17
Year of publication
2000
Pages
2817 - 2820
Database
ISI
SICI code
0094-8276(20000901)27:17<2817:HHADEO>2.0.ZU;2-S
Abstract
HF-induced airglow at 630 nm was observed by the Digital All-sky Imager, lo cated near Skibotn in Norway, at F-region altitudes above the EISCAT HF fac ility near Tromso on 21 February 1999. The transmitter was operated in a 4- min on, 4-min off sequence at 4.04 MHz O-mode with the beam pointing vertic ally. The airglow reached a peak intensity of about 100 R above background and appeared equatorward of the HF beam's projection on the reflection alti tude, which was obtained from ionograms. Generally, the region of maximum a irglow was displaced towards the magnetic field line (zenith angle = 12.8 d egrees S) passing through Lire HF facility. This is a unique feature of the se observations. From mid-latitude studies, such airglow is thought to be e xcited either by electrons energised to several eV by plasma turbulence, or by thermal electron temperature enhancement. Such localisation towards the magnetic field is unexpected for both mechanisms of airglow generation and suggests this feature may be important at high latitudes.