According to the ground-based spectral observations of airglow emissions in the near infrared at Zvenigorod in 2000-2019, multi-year changes in the intensity of O2A(0-1) band at 865 nm and OH(6-2) band at 840 nm are studied. It was shown that the intensities of both the emissions had a significant negative long-term time trend and a positive response to the change of solar activity in the 11-year cycle. In the spectrum of their interannual harmonic variations, statistically significant quasi-decade and quasi-two-decade oscillations were found.
Simple digital filtering is used for studying mesoscale variations of the rotational temperature of excited hydroxyl (OH*) at heights 85 – 90 km according to the data of spectral measurements at observatories Zvenigorod (56°N, 37°E.) in years 2004 – 2016, Tory (52°N, 103°E) in 2012 – 2017 and Maymaga (63°N, 130°E) in 2000 - 2015. Monthly-mean values and standard deviations of OH* temperature disturbances with periods 0.7 – 8 hr are determined, which may reflect the intensity of internal gravity waves in the mesopause region. The filtering of mesoscale variations was performed by calculating the differences between the measured values of OH* temperature separated with time intervals of 0.5 - 2 hr. Seasonal and interannual changes in the mesoscale variances of the temperature at the observational sites are studied.