Seasonal Variations of Night Mesopause Temperature in Beijing Observed by SATI4

The data observed by a spectral airglow temperature imager (SATI) at Beijing National Observatory of Space Environment from July 23, 2008 to July 31, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH (6-2) and O 2 (0–1) airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 km is 201.2 K, higher than average temperature 194.8 K at 94 km. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120–150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscillation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.