The Study On Airglow In Middle And Upper Atmosphere

The middle and upper atmosphere, as an important part of atmosphere of the earth, is affected by lower atmosphere as well as the space environment and space condition of outside earth atmosphere. In this region,there are many photochemical phenomena and dynamical processes. One of the photochemical phenomena is airglow. When excited atmospheric molecule or atom transmits to lower level, the light with some wavelength will emit. The light is referred to as airglow. 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 atmosoheric composition, temperature, and density in the emission region, and mass and energy movements to or from this region. A fundamental project in the study on airglow is the photochemical model for airglow emission. Photochemical model can predict the intensity of airglow. However, most theoretical models are founded on the basis of observation. The theoretical model is eventually tested and verified by observation. Therefore, the thesis has two emphases: investigate the photochemical model for airglow and its application; analyse and process the observational data for airglow.The researches on photochemical model and its application are composed of following contents.1. The thesis detailly analyse the photochemical model for OH nightglow emission and investigate the contribution of reaction HO₂ +O→OH(v≤6)+O₂ on the vibrational-rotational bands in OH Meinel band nightglow emission. The results indicate that the reaction has large contribution to the vibrational- rotational bands with initial vibrational level less than 7. Furthermore, the lower the initial vibrational level, the larger the contribution of the reaction. 2. In this thesis, the photochemical model for O₂(1.27μm) nightglow is studied by comparing the height-latitude distributions of O₂ nightglow emission respectively calculated from model and observed by SABER. The results indicate that the most important reactions about O₂ nightglow emission are O + O + M→O₂(Δ)+ M and OH^* + O₂→O₂(Δ) + OH. The former is the main resource of O₂ nightglow above 88km and the latter is the main resource below 88km.3. OH nightglow emission rate is ofen used to infer the atomic oxygen density in the MLT region. However, the uncertainties of input parameters will affect the derived atomic oxygen density. In practical inversion, the inversion uncertainty due to the uncertainties of input parameters is not yet analysed completely. We systematically estimate the inversion uncertainties and find the papameters, the uncertainties of which have large contributions to inversion uncertainty. This is helpful to decide which parameters should be measured more accurately in the future.4. A method to derive the peak of the vertical distribution of atomic oxygen density in the MLT region is developed. This method changes the history that the intensities of three nightglow emissions must be measured simultaneously in order to derive the atomic oxygen density by using groundbased observation method. Because the intensity of OI558nm nightglow has been observed by many observatories at different latitudes and longitudes for many years, we have plenty of data for OI558nm nightglow. Our method is useful for extracting the longterm, large size spacial variation in the peak of atomic oxygen density.Using the method, we derive the peak density of atomic oxygen from the intensity of OI558nm nightglow observed at 52°N during 2000-2004. The nocturnal variation and seasonal variation in the peak density are analysed.The analyses on observational data of airglow emission maily include:1. We analyse the nocturnal and seasonal variations in the intensities of OI558nm nightglow and OI630nm nightglow observed by the geophysical observatory of ISTP SD RAS during 2000-2004.The observatory is situated at 52°N, 103°E.2. We analyse the correlation between the intensity of OI558nm nightglow and intensity of OI630nm nightglow observed by the geophysical observatory of ISTP SD RAS during 2000-2004. The results indicate they are correlative. The night number that correlation coefficient is between 0.7-0.9 is large and the probability for positive correlation is larger than that for negative correlation. The correlation between the two intensities reflects the coupling between E region and F region because the OI558nm nightglow emission layer is mainly situated in E region and the OI630nm nightglow emission layer is mainly situated in F region at middle latitude.3. The spacial and temporal distribution features of O₂(1.27μm)airglow, OH(1.6μm)aiglow and OH(2.0μm)airglow observed by SABER during 2002-2007 are analysed statistially. One of the results shows that the lowerest peak heights of three airglow emissions are all at equator, the peak heights at middle latitudes at winter hemisphere is lower than those at summer hemisphere.4. We analyse the long term periodic variation and nonperiodic variation in atmospheric temperature, density, O₂(1.27μm) airglow, OH(1.6μm)airglow and OH(2.0μm)airlow observed by SABER during 2002-2007 using Lomb-Scargle periodogram method and harmonic fit method. The results indicate that the strongest variations in these five paprameters are AO and SAO. Near equator, QBO in temperature, density, and peaks and peak heights of night average OH(1.6μm)airglow emission and night average OH(2.0μm)airglow emission near is strong. The AO in the peaks and peak heights of night average OH(1.6μm)airglow emission and night average OH(2.0μm)airglow emission at southern hemisphere is antisymmetric with that at northern hemisphere. At equator, the peaks of OH(1.6μm)airglow emission and OH(2.0μm)airglow emission increase with the peak heights decreasing.