Ground-based Observations of O2+ 1N Band Enhancements Relative to N2+ 1N Band Emission
Planetary and Space Science
Spectrometric measurements in normal aurora of O2+ first negative (1N) and N2+ first negative (1N) emissions over the wavelength range 5175–5325 Å have been obtained with coincident incoherent scatter radar measurements with both instruments pointed in the same direction, the geomagnetic zenith. A comparison of the inferred mean energies derived from the radar observations for several normal aurora was made with the spectral ratio obtained from the optical observations. The intensity ratio was found to decrease by nearly 40% from aurora with mean energy ∼ 10 keV to aurora with mean energy ∼ 2 keV. The altitude of the peak E-region electron density co-varied with the spectral ratio from ∼ 105 km for the harder aurora to ∼ 130 km for the softer aurora. The inferred rotational temperature from the matching synthetic spectra co-varied from 250 to 500 K over the same energy limits. Model analysis based on both mono-energetic and Maxwellian precipitating electron fluxes show reasonable agreement with the observed ratio when MSIS n(O2) and n(N2) densities corresponding to the experimental dates are used.
R.J. Niciejewski, J.W. Meriwether Jr., A.Vallance Jones, R.L. Gattinger, C.E. Valladares, V.B. Wickwar, J. Kelly, Ground-based observations of O2+ 1N Band enhancements relative to N2+ 1N band emission, Planetary and Space Science, Volume 37, Issue 2, February 1989, Pages 131-143, ISSN 0032-0633, 10.1016/0032-0633(89)90001-9. (http://www.sciencedirect.com/science/article/pii/0032063389900019)