Multi-Year Variations in Temperature in Mesopause Region and F2-Region Peak Electron Density over Eastern Siberia

Abstract

We performed an analysis of year-to-year variations in the characteristics of the upper neutral atmosphere and the ionosphere over Eastern Siberia. The mesopause temperature (Tm) obtained from the spectrometric observations of the OH(6-2) emission and the peak electron density (NmF2) from the ionosonde measurements were used as atmospheric and ionospheric characteristics. We considered the annual mean Tm and yearly average values of NmF2, as well as yearly average values of day-to-day and intradiurnal variability in Tm and NmF2. To interpret the year-to-year variations, we use multiple regressions of the ionospheric and atmospheric characteristics on the F10.7-index (as a proxy of solar activity) and Ap-index (as a proxy of geomagnetic activity). For the atmospheric characteristics, we also used regressions on the SOI index (as a proxy of circulation in the lower atmosphere). The yearly average values of NmF2 are dominantly controlled by changes in the solar flux. The year-to-year variations in the NmF2 variability are mainly driven by changes in both solar and geomagnetic activity. The year-to-year variations in the mesopause temperature weakly correlate with changes in the indices of solar and geomagnetic activity. The yearly average values of Tm variability correlate with changes in the SOI-index: the day-to-day variability demonstrates a positive correlation with the SOI-index, while the intradiurnal variability shows a negative correlation with the SOI-index. The study did not reveal a significant relationship between the year-to-year variations in the NmF2 variability and Tm variability.