Radiative Properties Of TLEs And The Retrieval Algorithm Of The Ionospheric Electron Density By The Nightglow FUV Emissions

There are two common luminous phenomena in the middle and upper atmosphere, transient luminous events(TLEs) and airglow. Transient luminous events are large scale optical events occurring at high altitudes, which are related to the electrical activity. TLEs are harmful to aircraft and spacecraft. And they will cause interference to the optical detector. Airglow is the photochemical phenomenon that when excited atmospheric molecule or atom transmits to lower level, the light with some wavelength will emit. The intensity of airglow depends on the photochemical emission mechanism as well as the density and the dynamics of the atmosphere. Airglow is therefore a powerful tool in investigations of atmospheric composition, temperature, and density in the emission region. In this paper, the radiation characteristics of the two kinds of luminous phenomena are studied mainly.Firstly, firing rate and volume radiation intens ity of typical emission band of Red Sprites were calculated based on simplified model of the quasi electrostatic field in typical discharge conditions. And the spectra is calculated when the effects of atmospheric transmission are considered. Studies have shown that, it is difficult to observe TLEs during the day. At night, TLEs radiation intensity varies with different ozone and water vapor content.Tnen, firing rate and volume radiation intensity of the nighttime OI 135.6 nm airglow emissions are calculated according to the excitation mechanism in the middle and upper atmosphere. The volume emissive rates at the band could be obtained considering the radiative scattering of the atmospheric oxygen atoms and absorption of oxygen molecules in the band at the radiative transfer process. The distribution of the 135.6 nm nightglow in the low- latitude area is obtained.Finally, the retrieval algorithm of the peak electron density NmF2 and the total electron content TEC by measuring the nighttime OI 135.6 nm airglow emissions is introduced in this paper. And this inversion algor ithm is checked in the exper iments. The results show that the inversion method is correct and feasible.