Observations Of The Far Ultraviolet Dayglow Emissions And O/N₂Inversion Methods

Far Ultraviolet (FUV) dayglow emissions in the ionosphere, are produced byphotoelectrons impact on the particles of the upper atmosphere, and provide theoptical signals for remote sensing of chief neutral particles (N2, O, O2) of theionosphere. Observations of the FUV dayglow emissions from space can be apowerful method to derive the useful information on the densities and thedistributions of the chief neutral particles. Therefore, research on the FUV dayglowemissions has important scientific and application values. In this dissertation, wemainly study the LBH dayglow emissions in the range of140-180nm and the OI135.6nm dayglow emissions, which are the observation signals of the Wide-fieldAuroral Imager (WAI) and the Ionospheric Photometer respectively, and these twoinstruments will be carried on satellite FY-3D. So, this dissertation provides a solidbasis for simulating the image of ionospheric LBH dayglow emissions and the O/N2inversion technique.1. Firstly, the radiative transfer theory of the FUV dayglow emissions, the transfertheory of the photoelectrons, and the theory of auroral electrons have beenintroduced. Furthermore, we mainly analyse the excitation process, the absorptionprocess, and the scattering process of the FUV dayglow emissions in the ionosphere, so this work provides basis for studying the emission characteristics of the LBHdayglow emissions in the range of140-180nm and the OI135.6nm dayglowemissions.2. According to direct excitation theory and spherical geometry, the spectralcharacteristics of the LBH emission are analyzed and a revised method (RAURIC) tocalculate the column emission rate of the LBH dayglow emissions for large field ofview is given. Two main limitations of AURIC, that are the definition of theobservation azimuth angle and the treating of the solar zenith angle as a constantalong a line of sight, are improved in RAURIC. The column emission rates of theLBH bands in the range of140-180nm are calculated with the method. Comparisonswith results from AURIC show great agreement in nadir, while RAURIC should beused in other lines of light, especially for large field of view.3. We aim at the LBH band in the range of140-180nm and the OI135.6nmdayglow emissions, the observation signals of payloads on the meteorologicalsatellite FY-3, and do initial research on the O/N2retrieval technique for the firsttime. In our work an important finding is that135.6/LBH is correlated with solaractivity. Then we check the effects of the solar activity on the O/N2retrieval curves.And the results show that there are large deviations between the retrieval curves withdifferent solar activities, so the solar activity effect must be considered to beremoved in the O/N2retrieval method.