The maximum increase in the phase delay of the JXN radio signal during the solar eclipse on August 11, 2018 was 0.256 radians (09:48 UT) and 0.227 radians (09:56 UT) during VLF registration at Tixie Bay and Yakutsk, respectively. The normalization coefficients relating the effective height changes of the Earth-ionosphere waveguide and the logarithm of the ratio of the solar radiation flux during the eclipse to the total radiation flux for the daytime are 3.43 ± 0.21 and 2.23 ± 0.09 km for the JXN – Tixie Bay and JXN – Yakutsk radio paths respectively. According to our estimates for the segment of the JXN – Tixie Bay path (75° N, 113° E, a local maximum eclipse at 09:43:48 UT, the linear phase Φ = 0.628) the maximum increase of the effective height of the Earth-ionosphere waveguide was 2.28 km. For the segment of the JXN – Yakutsk path (70° N, 113° E, a local maximum eclipse at 09:56:24 UT, the linear phase Φ = 0.627) the maximum increase of the effective height of the Earth-ionosphere waveguide was 1.47 km. At the partial reflection radar of the PGI (69.0° N, 35.7° E) the eclipse was just before local noon when electron density of the lower ionosphere increased and the effect of a relatively weak solar eclipse was not detected (the maximum of the eclipse linear phase Φ = 0.313 at 09:27 UT).
On November 16, 2017 at 16:40:22 UT over Northern Finland a powerful meteor explosion had occurred. Entry of the meteor was recorded by the all sky camera at the radio physical observatory Verkhnetulomsky (68.59°N, 31.75°E), and response of the high-latitude lower ionosphere to this explosion was recorded by the radar of the partial reflections at the radio physical observatory Tumanny (69.0°N, 35.7°E). After the explosion the considerable disturbances in the ordinary wave amplitude at the heights of 80-95 km have appeared. Using the temporal variations of the ordinary wave amplitude the periods corresponding to resonant atmospheric modes were identified: the acoustic cut-off period and the BruntVäisälä period, and also temperature of the atmosphere and sonic speed at the mesopause heights were calculated. It was suggested that the disturbances could be caused by the waves which had magnetohydrodynamic nature.
Reaction of the high-latitude lower ionosphere and the geomagnetic field to the Vilyuysk meteoroid explosion according to amplitudes of partially reflected ordinary and extraordinary waves, received by the partial reflection facility of the Tumanny observatory (69.0°N, 35.7°E), and geomagnetic field variations of the Lovozero observatory (68.0°N, 35.0°E) of the Polar Geophysical Institute had been considered. The meteor has blown up at 21:29 UT, 4 March 2014, in the sky over the Vilyuysk district of Yakutia (64.3°N, 123.1°E). It was shown that explosions have caused changes in the ionosphere and the geomagnetic field, and also appearance of waves of different types: internal gravity waves and slow magneto-hydrodynamic waves.
The observatory Lovozero (68.0N, 35.0E, Polar Geophysical Institute) carries out regular observations of aurora. During the aurora observations in some cases the luminescence of the night sky had a wavy structure with the wavelengths of several tens kilometers and with the temporary periods about 15-30 minutes. For two cases comparisons with data of the radar of partial reflections in the observatory Tumanny have been carried out. Maxima of reflection amplitudes of the radar took place at the heights of 80-90 km and amplitudes at these heights had the periods similar to the periods of fluctuations of luminous intensity of the sky. It allows assuming that the wave structures in the luminescence were caused by acoustic-gravity waves.
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