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In an analysis of 6300‐Å nightglow measurements obtained at Arecibo on the night of April 25/26, 1976, Cogger et al. (1980) reported that model estimates exceeded the observed 6300‐Å intensity by a factor of 2. We have reanalyzed the data in light of newer laboratory and aeronomic determinations of the parameters used to calculate the 6300‐Å intensity and now obtain agreement with the measurements. The rate coefficient for the reaction O+ + O2 → O2+ + O required to fit the data is 27% smaller at 700 K than previously assumed, but is in agreement with the thermal drift tube measurements of Chen et al. (1978). A specific recombination rate of 1.2×107 cm³ s−1 (at 700 K) for production of O(¹D) from O2+ is consistent with the data. This value is somewhat smaller than the recent theoretical calculation of Guberman (1988) for recombination from O2+(υ = 0) and may imply that O2+ is not completely vibrationally relaxed in the nighttime thermosphere. The reaction N(²D) + O2 → NO + O(¹D) contributes <10% to nightglow 6300‐Å production, even for an assumed O(¹D) yield of unity. Quenching of O(¹D) by O(³P) and the larger transition probabilities suggested by Abreu et al. (1986) result in calculated 6300‐Å intensities virtually indistinguishable from those obtained using the rate coefficients of Link et al. (1981). This suggests that it will be difficult to verify O(¹D) quenching by atomic oxygen using nightglow measurements.

Abstract. Energetic electrons can penetrate into the middle atmosphere causing excitation, dissociation, and ionization of neutral constituents, resulting in chemical changes. In this paper, representative electron spectra measured by the Upper Atmosphere Research Satellite particle environment monitor are used to determine the relative contributions of bremsstrahlung X rays and direct electron impact on the energy deposition and ionization production rates for altitudes between 20 and 150 km. Above 50 km most of the ionization comes from direct electron impact. However, in the stratosphere the energy contributed below 50 km is mostly due to bremsstrahlung X rays. In the diffuse aurora the ionization from the bremsstrahlung component exceeds that due to the galactic cosmic ray background to altitudes as low as 30 km during geomagnetically active periods. This paper demonstrates that a diffuse auroral source can input as much or more energy into the upper portion of the lower and middle atmosphere as previously reported for relativistic electron events. The effects of the diffuse aurora (including both the direct electron and the bremsstrahlung contributions) on atmospheric chemistry may be significant.

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An analysis of satellite STP78‐1 measurements at solar maximum of the latitudinal variation of O I EUV dayglow emissions at 1356, 1304 and 989 Å is presented. The day glow intensity measurements corroborated by Atmosphere Explorer‐E data indicate that the exospheric temperature was about 220–240 K higher than predicted by the MSIS‐83 thermospheric model. In addition, the temperature variation with latitude is not as large as predicted by MSIS‐83 for day 80, 1979. The 1304‐ and 1356‐Å intensity measurements are consistent with electron impact excitation cross‐section measurements of Zipf and Erdman (1985). The 989‐Å excitation cross section of Zipf and Erdman (1985) requires a branching ratio of 7×10−4 for transitions other than 989‐Å in order to produce agreement with our data. The Vaughan and Doering (1987) direct 3s' ³D° excitation cross section, about a factor of 3 smaller than the optical excitation cross section of Zipf and Erdman (1985), is also compatible with our 989‐Å data for a branching ratio near 1×10−4. The solar 1304‐Å spectral irradiance inferred from the observations is about a factor of 2 lower than the rocket measurements of Mount et al. (1980), but is consistent with Solar Mesosphere Explorer results. Our measurements also suggest that enhancement of the 1304‐Å electron impact excitation cross section due to radiative entrapment of cascade‐feeding photons is negligible.