Oxygen atmospheric and infrared atmospheric bands in the aurora

Abstract

Two rockets, instrumented to measure auroral optical emissions and many other auroral parameters, were flown from Fort Churchill on March 21 and 30, 1969, into two similar auroras. The intensities of both the atmospheric and the infrared atmospheric bands of O2 were found to be extremely high, both absolutely and relative to the N2+ radiation at 3914 A. Although the O2 emissions were generally spatially correlated with the N2+ emissions, consistent differences in volumes of emission were observed, implying that the O2(¹Δg) must be excited by a different process than the N2+. Consequently, many possible excitation mechanisms were studied. It was concluded that much energy is deposited into the auroral atmosphere through mechanisms other than direct excitation by energetic particles. Although there were insufficient data to draw absolute conclusions, a possible mechanism, which appears to be consistent with the experimental results, is electric field heating of ambient electrons and the subsequent excitation of O2 molecular electronic states.