The Detection And Study On Airglow Spectra In Middle And Upper Amosphere

Airglow is one of significant photochemical phenomena emitted by atoms or molecules in the middle and upper atmosphere, which is affected by the lower atmosphere rmeteorogical activities and the solar radiation. Airglow as an indicator of atmospheric photochemistry and dynamics is extensively used to study chemistry and physics in middle and upper atmosphere. Therefore, a ground-based instrument used to detected atmospheric radiation was developed at Xinglong, Hebei Province（40.39°N, 117.58°E） in November, 2011. The system is designed on the basis of scientific spectrometer, CCD detecter, the front optical system and the software. Ten significant atmosphere airglow spectral bands are in turn observed during the night, the wavelength of which is in the range of ⁵30nm to ¹000nm. The observed spectra include OI 557.7nm green line, OI 630.0nm red line, O₂（0-1） band and OH（8-3, 4-0, 5-1, 9-4, 6-2, 7-3, 8-4, and 3-0） bands. Then the continuous observations are used to study photochemistry and dynamics in middle and upper atmosphere,and the three works are carried out:1. Einstein coefficient data sets are evaluated by comparing the ground-based OH rotational temperature with SABER’s, and a set of optimal Einstein coefficients ratios for rotational temperature are derived.The rotational temperatures derived from ground-based observations of OH airglow emissions are commonly used to investigate the photochemistry and dynamics in the mesopause. When the rotational temperature is calculated, the Einstein coefficients obtained by ab initio computation are needed. However, many data sets of OH Einstein coefficients have been published are different from each other, and the rotational temperatures calculated using the Einstein coefficients also have different values. The kinetic temperature from Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics/Sounding the Atmosphere by Broadband Emission of Radiation（SABER） is completely independent of the OH rotational temperature. By comparing the ground-based OH（9-4, 8-3, 6-2, 5-1, 3-0） bands rotational temperatures with SABER’s, five Einstein coefficient data sets are evaluated. The results show that temporal variations of the rotational temperatures are well correlated with SABER’s; the linear correlation coefficients are higher than 0.72. The rotational temperatures calculated using each set of Einstein coefficients produce a different bias with respect to SABER; these are evaluated over each of the vibrational levels to assess the best match. It is concluded that rotational temperatures determined using any of the available Einstein coefficient data sets have systematic errors. However, of the five sets of coefficients, the rotational temperature derived with Langhoff et al.’s（1986） set is most consistent with SABER. In order to get a set of optimal Einstein coefficients for rotational temperature derivation, we derive their ratios from ground-based OH spectra and SABER temperatures statistically using 3 years of data. The use of a standard set of Einstein coefficients will be beneficial for comparing rotational temperatures observed at different sites.2. The responses of O₂ and OH to atmospheric waves are studied using the ground-based observations.The airglows are significantly fluctuated by waves including atmosphere gravity wave, tides and planetary waves. The fluctuations in airglow, such as OH, O₂, O, Na and so on, have been observed. When the waves pass through the airglows layers, the intensities and temperatures will both have responses. The parameter η first introduced by Krassovsky is defined as the ratio of the relative variations of intensity and the rotational temperature. The O₂（0-1） atmosphere system band and OH（6-2） band are used to study the airglow responses to atmospheric waves with different periods. For the periods less than 12 hours including atmospheric gravity waves and tides, |η| of O₂ is in the range of about 1 to 10 and increases with periods increasing, and the phase differences between the intensity and temperature fluctuations are negative, i.e., the temperature leads to intensity; |η| of OH（6-2） is also in the range of about 1 to 10, but does not vary with periods, and the phase is nearly less than 0. For periods larger than 2 days, |η| of O₂ is in the range of 11 to 15, and the phase difference is close to 0; |η| of OH（6-2） is in the range of 5 to 11, and the phase difference is also close to 0. The comparison between the observation and the modeling indicates that the present theories are still not in agrrement with the observations. In fact, the airglow responses to waves are controlled by airglow generation mechanism, the quenching processes and atmosphere background, especially the atom O vertical distribution. So if the above processes are not understood, the modeling of η will not be the same to the observations.3. The rotainal temperature of OH over Bejing is compared with SABER’s to study the seasonal variation of temperatures in the mesopause.The rotational temperature of OH（6-2） band observed from 2012 to 2013 was compared with SABER’s and used to study seasonal variation, annual variation and variations during nights over Beijing, China. It is showed that the mean temperatures of OH（6-2） band and SABER during 2012-2013 are respectively 196.8 K±13.1 and 196.3 K±11.9. The two have the same seasonal variations, with the maximum temperature in winter and the minimum temperature in summer. The annual and semiannual components are used to fit the daily mean rotational temperatures, and the annual amplitude of 13.7 K is greater than semiannual amplitude of 1.7 K. Their phases are respectively at mid-December and late-March.