TEC variations in equatorial ionosphere during June 21, 2020 solar eclipse

Abstract

Relevance. Solar eclipse (SE) is characterized by numerous dynamic processes in all the Earth's shells and geophysical fields. Each SE is the cause of regular and irregular effects that are unique. This is influenced by the SE magnitude, geographical coordinates, solar activity, time of year, time of day, atmospheric and space weather and other factors. Therefore, the task of a comprehensive and in-depth study of physical processes in geoshells for each new SE is relevant.

The aim of this paper is describing of the results of the analysis of vertical TEC caused by the SE on June 21, 2020 in the area near the Earth's equator. The eclipse was unique in that it was observed in equatorial and subtropical latitudes near the summer solstice and was annular character.

Methods and Methodology. Indian stations located south of the SE magnitude region were selected for analysis. The total error of the TEC assessment does not exceed 0.1 TECU.

Results. Temporal variations of TEC for the trajectory of satellites and the location of receiving stations south of the region of maximum eclipse were analyzed. For most time dependences of the TEC N_V(t), the magnitude of the ΔN_V depression was increased with growth coverage of the Sun's disk. The differences in this dependence can be explained by the peculiarities of the ionosphere in the equatorial belt of the Earth. The largest depression in TEC could be 4 TECU at M_max » –0.643. The relative variations in the electron concentration were –19%. In the morning, the decrease in TEC did not exceed 2 TECU according to N_V0 » 13.5–14.5 TECU. The relative decrease in electron concentration d_V = –11%. During the annular eclipse, changes in the waveform character in variations in the concentration of electrons were practically not detected.

Conclusions. The parameters of TEC temporal variations in the equatorial ionosphere during the annular SE on June 21, 2020 have been established.