Temperature Changes in the Mesopause Region due to Climate Changes in Recent Decades (1960–2024)

The results of an analysis of temperature variations in the mesopause region based on long-term measurements of hydroxyl airglow at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (ZSS IAP RAS) during 1960–2024 against the global-scale climate changes are presented. Along with temperature variations in the mesopause region, two versions of temperature variations in the mesopause region, normalized to the same level of solar activity, were analyzed. Quantitative estimates of a significant decrease in temperature in the mesopause region over the past decades in winter, against the background of global surface temperature increases, were obtained. Additionally, using cross-wavelet analysis of data for the time interval 1960–2024, significant coherence of their most long-term variations with the surface temperature in the Northern Hemisphere was noted, which had not been observed in data for shorter time intervals. The possibility of such coherence was predicted in (Mokhov et al., 2017) in the context of continued global warming based on the results of model simulations for the 20th–21st centuries, taking into account anthropogenic forcing, but it had not been observed in obsevational data for shorter time intervals. Along with long-term trends, notable features include a sharp temperature drop in the mesopause region during the 1970s and its synchronicity with the well-known shift in surface climate regimes associated with El Niño events. The results of cross-wavelet analysis using data obtained at ZSS IAP RAS for the time interval 1960–2024 indicate a more significant connection between temperature variations in the mesopause region and El Niño indices in recent decades.