Retrieval Of Temperature For Near Space Atmosphere Based On Oxygen A-band Emission Spectrum

The atmospheric temperature parameters in the near space not only greatly affects the safety prediction of spacecraft launch and re-entry,but also provides data for the establishment of atmospheric dynamics model and the physical mechanism of photochemical coupling.Therefore,the study of the atmospheric temperature field in the near space as a hot spot in the international research has important scientific significance and extensive application value in the world.Currently,there have been some international studies on the temperature profile of the near space,but there is still a lack of research in this field in China.The main contents of this paper include the following aspects:?1?Based on the photochemical reaction mechanism,atmospheric dynamics and photochemical reaction theory of oxygen A-band airglow,a photochemical model was established,and then the volume emission rate?VER?and limb radiation intensity of oxygen A-band airglow are calculated based on the photochemical model.In order to verify the correctness of the model,compared with the simulation results of AURIC model,the VER of nightglow is very consistent with the corresponding height.Based on the results of calculation and simulation,the influence factors of VER and radiation intensity of oxygen A-band airglow are analyzed,including VER of nightglow along with the change of temperature and oxygen atoms number density,VER of dayglow along with the change of the solar zenith angle,oxygen A-band emission spectrum along with the change of temperature and radiation intensity varies with the change of the tangent point height.?2?In order to select a more suitable inversion method,two different algorithms,Bayes method and least square method,were used to carry out temperature inversion based on limb radiation intensity of oxygen A-band,and the results were compared and analyzed.Below 80 km,When the SNR is between 66 and 337,the mean inversion errors of the three spectrum lines of 761.59nm,762.2nm and 764.05nm based on bayesian inversion are 6.04k,2.5k and 4.81k respectively;the mean inversion errors were 23.27K,11.84K and 17.97K,respectively.When the SNR is 6?34,the mean inversion errors of the three bayesian lines are 37.55k,16.76k and 28.50k,respectively.The mean errors of the least square inversion are 180.26k,65.61k and121.33k,respectively.?3?Based on the simulation data of the near space radiation intensity of oxygen A-band,the atmospheric temperature inversion of the near space?60-110 km?was studied and the results were analyzed.First of all,based on the forward model simulated with noise and without noise interference in the case of limb radiation simulation value.Based on these two kinds of simulation data,temperature inversion was carried out respectively,and the inversion results of all spectral lines in oxygen A-band were analyzed,and the weight function variation rule of each spectral line was determined as a judgment basis for spectral line selection.Without noise,when the influence of temperature on the self-absorption is less than the influence on the line strength,the temperature inversion precision is higher,with an average inversion deviation of 4.1k.When the influence of temperature on self-absorption is greater than that on line strength,the inversion precision of temperature is poor,and the average inversion deviation reaches 34.9k.In addition,based on the weak line,this paper further analyzed the influence of radiation intensity on the inversion accuracy by improving the signal-to-noise ratio,and found that the stronger the radiation,the greater the signal-to-noise ratio,the higher the temperature inversion accuracy,and vice versa.When the line strength of the airglow spectrum reaches 10^-26,it can also be used for temperature inversion over 80 km and obtain good inversion results with the inversion accuracy<5K.