Long-Term Changes in the Activity of Wave Disturbances in the Mesopause Region.

Long-term trends and dependences on solar activity were derived for wave disturbances at mesopause altitudes (80−100 km) based on temperature variations obtained by spectral observations of the hydroxyl airglow at the Zvenigorod Science Station, Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, in 2000−2024, as well as by methods of statistical analysis. Their activities were determined by digital frequency filtering in three regions of wave periods, such as 0.7−2.0, 1.4−4.1, and 2.7−8.2 h with maxima at 1, 2, and 4 h. The root-mean-square values of temperature half-differences served as an indicator of wave activity. Both year-round and average seasonal (winter and summer) values were analyzed. According to the study results, the wave activity is characterized by positive trends with their dependence on the frequency band of disturbances (in winter, the trend is greater in the high-frequency band, and in summer, the trend is greater in the low-frequency band). The dependence on solar activity is positive. Its values are greater for the high-frequency band of disturbances, as well as in winter. [ABSTRACT FROM AUTHOR]