STUDIES OF AURORAL HYDROGEN EMISSIONS IN WEST-CENTRAL CANADA: II. VARIATIONS IN THE INTENSITY RATIO BETWEEN THE Hβ LINE AND THE λ 4 709 N2+ BAND

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Abstract
The results of a large number of measurements of R(Hβ), the intensity ratio of the Hβ auroral line, and the λ 4 709 (0, 1) first negative N2+ band from Canadian IGY patrol spectrograms are presented. Only 3% of these ratios exceed unity, while half of them are less than 0.2. Comparison with a theoretical value of about 3.0 for proton excitation indicates that only a small fraction of aurora is so excited. The rare occurrence of values of R(Hβ) near 3.0 suggests that pure proton excitation does sometimes occur, however. Values of ratios of the brightnesses of Hβ averaged over several spectrograms to those of λ 4 709 similarly averaged have been shown to exhibit geomagnetic, latitudinal, and diurnal variations. The highest average ratios occur in the early evening, while the lowest values are observed in the late morning in post-breakup forms. The diurnal and latitude variations in these average ratios support the hypothesis that there is a zone of proton precipitation showing a characteristic behavior relative to the zones of electron excitation.

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