Spectroscopic Study of the Nitrogen Airglow

Four rocket observations of the NO γ(1, 0) 2148 Å band airglow and ground observations of the NI 5200 Å emission in the auroral zone are presented. A radiometer was developed to measure the NO γ(1, 0) band airglow in the mesosphere and thermosphere. It can extract the γ(1, 0) band airglow from intense background radiations by making use of a self-absorbing gas cell. NO density profiles were deduced from the γ(1, 0) band emission rates measured at Uchinoura (31°N), Thumba (9°N) and Syowa Station (69°S). The NO densities in the thermosphere obtained at middle and low latitudes are found to vary with solar activity. In view of a considerable temperature dependence of the production rate of NO in the thermosphere, the variation may be attributed to change in thermospheric temperature, which is closely related to solar activity. Change in the solar extreme ultraviolet radiation flux may also be responsible for the variation. The NO density in the mesosphere and the lower thermosphere obtained in the auroral zone is found to be larger than those obtained at middle and low latitudes under the conditions of similar solar activity. Because of a long life time of NO in the altitude region, the observed enhancement may be due to the after-effect of a particle precipitation event which occurred within a day before in despite of no polar disturbance during the flight. The emission rate of the NI 5200 Å doublet in the aurora was measured with a tilting-filter photometer at Syowa Station from March to September 1977. The N_2^+ 1NG(0, 1) 4278 Å band emission was measured simultaneously with the 5200 Å emission for comparison. Examining nighttime variations of the emissions obtained in thirteen clear and moonless nights, the 5200 Å emission is found to be one of the common spectral features of the aurora. A simple model calculation is performed to investigate the excitation mechanism for the 5200 Å emission in the aurora, and dissociative recombination of NO^+ is found to be insufficient to explain the observations. Alternatively, impact dissociation and excitation of N_2 by auroral electrons may be the major excitation process. The ratio of measured 5200 Å emission rate to the 4278 Å emission rate decreases as the 4278 Å emission rate increases. This tendency may be qualitatively explained by the combined effect due to the highly forbidden nature of the 5200 Å emission and the characteristics of the precipitating particles in that their mean energy generally increases with their total energy

Fast flickering aurora within traveling current vortices

第6回極域科学シンポジウム[OS] 宙空圏11月16日（月）　国立極地研究所１階交流アトリウ

Rocket Observations of Nitric Oxide Density Profile and Ground Observations of the 5200 Å Emission at Syowa Station, Antarctica (f. Polar Ionosphere) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and the Magnetosphere in the Polar Regions : Part II)

The nitric oxide density profile between 72 and 120 km was measured with a specially designed ultraviolet radiometer making use of the resonant fluorescence in the γ(1,0) band near 2150 Å aboard a sounding rocket launched at Syowa Station (69°S, 39.6°E) under geomagnetically quiet conditions. The observed nitric oxide density was found to be much larger than those obtained at middle and low latitudes. It can be attributed to the after-effect of particle precipitations during the previous night. The 5200 Å emission from metastable atomic nitrogen, N(^2D), was measured at Syowa Station by the tilting filter method. The characteristic of observed 520 Å emission seems to show the dominance of particle impact excitations rather than dissociative recombination excitation

Rocket Measurement of Mesospheric Ozone at High Latitude (f. Polar Ionosphere) (Proceedings of the Second Symposium on Coordinated Observations of the Ionosphere and the Magnetosphere in the Polar Regions : Part II)

A rocket measurement of the vertical distribution of ozone in the mesosphere has been made under a high latitude winter condition, with the solar ultraviolet absorption method. The measured ozone concentration at 60 km was l.7×10^9 cm^3, which was much lower than the typical value of that measured at the mid-latitude