Lunar Tides in the Mesopause Region Obtained from Summer Temperature of the Hydroxyl Emission Layer

The summer mesopause region (altitudes of 82–92 km) is the coldest place in the Earth’s atmosphere; it is influenced by external effects, including lunar tides. In this study, we isolate the lunar tidal harmonics from the temperature series of the hydroxyl emission layer (OH*) obtained from spectrophotometric measurements at the Zvenigorod scientific station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, in the summer seasons of 2000–2016. The OH* temperatures are the weighted average in a layer of ~9 km thick, which has a maximum at an altitude of ~87 km. The analysis made it possible to distinguish lunar oscillations, among which two harmonics in the temperature of the mesopause region are identified for the first time. These oscillations are recognized as the second harmonic of the anomalistic lunar tide (the mean period is ~13.78 days) and the lunar tide with a period of 8 h 17 min, or, interpreting alternatively, the third harmonic of the lunar synodic month (~9.84 days).