Observation of O+ (4P-4D0) lines in electron aurora over Svalbard

• Published in: Annales Geophysicae
• Main Authors: Ivchenko, N., Rees, M. H., Lanchester, B. S., Lummerzheim, D., Galand, M., Throp, K., Furniss, I.
• Format: Text
• Language: English
• Published: 2018
• Subjects: Norway; Svalbard
• Online Access: https://doi.org/10.5194/angeo-22-2805-2004; https://angeo.copernicus.org/articles/22/2805/2004/

This work reports on observations of O + lines in aurora over Svalbard, Norway. The Spectrographic Imaging Facility measures auroral spectra in three wavelength intervals (H β , N + 2 1N(0,2) and N + 2 1N(1,3)). The oxygen ion multiplet (4639-4696Å) is blended with the band. It is found that in electron aurora, the brightness of this multiplet, is on average, about 0.1 of the total brightness. A joint optical and incoherent scatter radar study of an electron aurora event shows that the ratio is enhanced when the ionisation in the upper E-layer (140-190km) is significant with respect to the E-layer peak below 130km. Rayed arcs were observed on one such occasion, whereas on other occasions the auroral intensity was below the threshold of the imager. A one-dimensional electron transport model is used to estimate the cross section for production of the multiplet in electron collisions, yielding 0.18x10 -18 cm 2 .