Research On Radiation Characteristics And Inversion Algorithm Of Vacuum Ultraviolet Ionospheric Optical Remote Sensing

The Ionospheric vacuum ultraviolet?10nm-200nm? airglow emission is an important energy source for the physical process of the middle and upper atmosphere,which is mainly produced by the photoionization and photoelectron impact ionization.The detection of atmospheric vacuum ultraviolet airglow emission is an important means of space-based remote sensing of the earth's ionosphere and thermosphere,from which the spatial distribution information of physical parameters such as the electron density profile of the ionospheric F layer,O⁺ ion density profile and O/N₂ can be obtained.Due to the absorption of molecular particles in the low thermosphere,the airglow Rayleigh scattering with the spectral wavelength below 200nm cannot be transmitted above the height of the thermosphere.It can isolate the radiation in the measurement area from the radiation in the upper atmospheric area,that is to say,when using the satellite platform to measure the airglow radiation in the vacuum ultraviolet band,the detection background is very clean,so vacuum ultraviolet detection is an ideal detection method for studying the ionosphere,and is also one of the main development trends of ionospheric detection in China.In this paper,we focus on the wide range of applications of vacuum ultraviolet in the ionosphere and thermosphere,including research on the radiation characteristics of O⁺ ion 83.4nm dayglow,O atom 135.6nm dayglow and N₂ Lyman-Birge-Hopfield Bands,then we develop the inversion algorithm for the detection data from FY-3D Ionosphere Photometer,which lays a foundation for the further development of the vacuum ultraviolet ionospheric detection technology.The main research results include:1?To study the radiation transmission mechanism of vacuum ultraviolet airglow,focusing on the analysis of the photoionization process,photoelectron impact ionization process,absorption process and resonance scattering process of the ionospheric vacuum ultraviolet airglow emission;2?Based on the transmission model of atmospheric ultraviolet radiation,we study the radiation transmission characteristics of O⁺83.4nm day airglow,the O⁺83.4nm radiation transmission model is realized by constructing Markov chain matrix.Based on this model,then we obtain the distribution of initial volume emissivity,volume emissivity under resonance scattering and limb emission intensity of 83.4nm dayglow by simulating calculation.Furthermore,we can explore the correlation between the O⁺83.4nm dayglow line and the ionospheric physical parameters such as altitude,latitude,solar activity and geomagnetic activity;3?Study the characteristics of oxygen atom 135.6nm and N₂ Lyman-Birge-Hopfield Bands,and develop the inversion algorithm to obtain the distribution of O/N₂ in the thermosphere;4?The filter filtering algorithm is used to pre-process the daytime measurement data of the Ionosphere Photometer on the FY-3D satellite,which further reduces the influence of remaining out-of-band stray light in the measurement data and effectively improves the accuracy of the data;5?Apply the developed inversion algorithm to the detection data of the FY-3D satellite ionospheric photometer to obtain my country's first O/N₂ distribution with complete intellectual property rights.Analysis of the O/N₂ data obtained from the Ionosphere Photometer during the magnetic storm in August 2018,the ionospheric photometer O/N₂ data was analyzed and compared with the measured inversion results of the Global Ultraviolet Imager?GUVI?.The results showed that:The O/N₂ products obtained by the developed inversion algorithm are in good agreement with the O/N₂ products obtained by GUVI.