Response of the Lower Ionosphere to the Partial Solar Eclipses of August 1, 2008 and March 20, 2015 Based on Observations of Radio-Wave Scattering by the Ionospheric Plasma Irregularities

Resumo

The results of observations of the ionospheric effects of the partial solar eclipses on August 1, 2008 and March 20, 2015 are presented. The observations were performed by the partial-reflection technique during scattering of radio waves by natural irregularities in the D region and the method of resonant scattering of radio waves by artificial periodic irregularities of the ionospheric plasma. A three- to fivefold reduction of the electron density in the D region was obtained by the partialreflection technique. Ionospheric response at altitudes above 88 km is delayed by 20–25 min relative to the time of the maximum eclipse phase, while in the bottom D region the time delay is a few minutes. Variations in the characteristics of the signals scattered by artificial periodic irregularities, as well as velocities of the vertical motion of the plasma in the lower ionosphere during the solar eclipse were studied. An increase in the scattered-signal amplitude during an eclipse in the E region by 30–40 dB was recorded, stratification of the D region was observed, and the appearance of signals scattered at the mesopause altitudes was detected.