A Temperature-Dependent Model of the Thermospheric Odd Nitrogen

Abstract

The diurnal variations of odd nitrogen species (N, NO) in the thermosphere are modelled by solving the time-dependent, one-dimensional continuity equations with the diffusion transport which have been developed by OGAWA and SHIMAZAKI (1975). By comparing the calculated results with N and NO distributions which were determined in an airglow (NI 5, 200Å and NO gamma-bands) and mass spectrometric observations the following conclusions have emerged. (1) The quantum yield of N(²D) in the reactions energetically capable of producing the excited species should be larger than 0.5, and probably as large as 0.9. (2) The quenching of N(²D) by atomic oxygen is important at altitudes above 120km. In order to be consistent with the observation of NI 5, 200Å airglow, the quenching coefficient must be as large as 1×10^-12cm³s^-1. (3) The variability of NO density profiles obtained by various experimenters is largely interpreted to be due to the large diurnal variations of odd nitrogen expected from a large diurnal change in the thermospheric temperature which is also under the control of solar activities.