Auroral E-region: Ion composition and nitric oxide

Data from eight auroral ion composition measurements, seven of which have been reported in the literature, are analyzed and compared in terms of a single model format. We find, contrary to conclusions published previously for two of the experiments, that there is no discrepancy concerning O⁺ ions. In general, the mean CIRA 1972 neutral model is found to be quite suitable as a representative of the major gas composition required for auroral E-region calculations which agree with the data. Nitric oxide profiles inferred from analysis of the data range from about normal non-auroral E-region nitrix oxide distributions with peak concentrations near 10⁸ cm^?3 to profiles with peak populations near 10⁹ cm^?3. Although the higher concentrations are generally correlated with intense aurora, we acknowledge that the length and strength of auroral activity prior to the individual rocket flights can have an even greater bearing, at times, on the NO “snapshot” profile deduced from the auroral ion composition data.