Seasonal variations of mesopause temperature and the amplitude of the VLF signals of the Novosibirsk radio station during 2009-2016

¹ Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy SB RAS, 677980 Lenin Ave, 31, Yakutsk, Republic of Sakha (Yakutia), Russian Federation
² Physical Technical Institute of the North-Eastern Federal University, 677000 Belinsky St., 58, Yakutsk, Republic of Sakha (Yakutia), Russian Federation

^* Corresponding author: korsakovaa@ikfia.ysn.ru

Abstract

Dynamics of seasonal variations of the amplitude of the VLF radio signal received in Yakutsk from the navigation station near Novosibirsk and the P-branches of the OH band (6-2) radiation intensity in the wavelength range 835 - 853 nm are considered. The radiation variations give information about mesopause region measured at the Maimaga station (130 km from Yakutsk). The observation from 2009 to 2016 covers period with minimum and maximum solar activity. The mesopause temperature and the VLF signal increase with increasing solar flux F10.7 in winter. The mesopause temperature seasonal variations and the VLF signal strength for the Novosibirsk-Yakutsk path are regularly inverted from year to year. By decade data averaging the VLF radio signal strength dependence on the temperature of the atmosphere at the OH excitation height can be expressed by a linear function. The coefficient of determination: R² = 0.59, the anticorrelation coefficient: r₁₀ = - 0.77. The variations of the VLF radio noise and the radio station signal for the eight-year interval are similar to solar activity (F10.7 index). The signal level of the radio station and radio noise registered in the winter is more sensitive to variations of F10.7 index in 24th solar cycle activity.