Because the 1.27 μm O2(a1Δg)airglow radiation has the advantages of strong radiation signal,large space span and weak self-absorption effect,it is an important target source for near-space atmospheric remote sensing.In addition,it has important scientific significance and application value,such as research on the dynamics and thermal characteristics of the middle and upper atmosphere,global greenhouse gas detection,and three-dimensional tomography of ozone concentration.Firstly,based on the photochemical model of O2(a1 Δg),the generation and annihilation mechanisms of O2(a1Δg)airglow were studied.The volume emission rate profile of O2(a1 Δg)airglow was calculated on this basis.Based on the spectral intensity and Einstein coefficients given by HITRAN,two methods for calculating the spectral distribution of O2(a1 Δg)airglow were proposed.Using the latest molecular spectral parameters,photochemical reaction rate constant and F10.7 solar ultraviolet flux,combined with the volume emission rate profile information of O2(a1 Δg)airglow calculated by photochemical reaction model.The radiative transfer theoretical model of the 1.27 μm O2(a1Δg)airglow in limb-viewing was developed by using a line-by-line integration algorithm.The influence of the self-absorption effect on the spectral intensity of airglow radiation at different tangent heights is analyzed.Then,the O2(a1Δg)airglow radiation spectrum of the target layer is obtained by processing the airglow radiation of the O2 molecule near the infrared atmospheric band measured by scanning imaging absorption spectrometer for atmospheric chartography(SCIAMACHY)under the limb-viewing by onion peeling algorithm.Spectral integration algorithm is used to retrieve the volume emission rate profile of O2(a1 Δg)airglow.Finally,the reliability and rationality of the radiative transfer theoretical model of the 1.27 μm O2(a1 Δg)airglow in limb-viewing is verified by comparing the radiation spectrum and the volume emission rate profile obtained from the theoretical calculation and retrieval of the SCIAMACHY instrument.Regarding the comparison results,factors that contribute to the limb radiation intensity and volume emission rate of O2(a1Δg)airglow are analyzed.Analyses show that theoretical calculations agree with measured satellite results in the altitude region above 50 km.However,the deviation between the two increases gradually with the decrease of altitude because the satellite remote sensing in the middle and low altitude regions are seriously affected by the self-absorption effect and atmospheric scattering effect in limb-viewing.Additionally,compared with the spectral line intensity parameter given by the HITRAN database,the O2(a1Δg)airglow limb radiation model based on Einstein coefficients is more consistent with the measured satellite results.Establishing the radiative transfer theoretical model of the 1.27 μm O2(a1Δg)airglow in limb-viewing provides a theoretical foundation for atmospheric remote sensing in near space.
O2(a1 Δg)band airglowVolume emission rateLimb-viewingRadiative transfer theoretical model
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