Observation of O+ (P-4-D-4(0)) lines in electron aurora over Svalbard

• Main Authors: Ivchenko, N, Rees, MH, Lanchester, BS, Lummerzheim, D, Galand, M, Throp, K, Furniss, I
• Format: Article in Journal/Newspaper
• Language: English
• Published: EUROPEAN GEOSCIENCES UNION 2004
• Subjects: Meteorology and atmospheric dynamics; Airglow and aurora; Ionosphere; Particle precipitation; Field-aligned currents; Optical aurora; Spectra; Oxygen; Radar; Impact; Excitation; Emissions; Scatter; N2; Norway; Svalbard
• Online Access: http://discovery.ucl.ac.uk/35955/

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-beta, N-2(+) 1N(0,2) and N-2(+) 1N(1,3)). The oxygen ion P-4-D-4(0) multiplet (4639-4696 Angstrom) is blended with the N-2(+) 1N(1,3) band. It is found that in electron aurora, the brightness of this multiplet, is on average, about 0.1 of the N-2(+) 1N(0,2) 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 (140-190 km) is significant with respect to the E-layer peak below 130 km. 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 0.18 x 10(-18) cm(2).