Item

Abstract

A solar eclipse is a daytime phenomenon that significantly disturbs the atmosphere and ionosphere during the moon obscuration. Significant atmospheric changes can trigger gravity waves that propagate upward and cause disturbances and irregularities during the obscuration. However, the nighttime disturbances and irregularities that occur after a solar eclipse are unclear. Here we reported the occurrence and development of disturbances and irregularities in the nighttime due to the solar eclipse on 21 June 2020. We analyzed the dense ground‐based Global Navigation Satellite System (GNSS) total electron content (TEC) data, the critical frequency of the ionospheric F2 layer (foF2) and its height (hmF2) recorded by the ionosondes data in East Asia during and after the solar eclipse occurred at June solstice. In the results, the eclipse induced not only a major daytime depression but also nighttime perturbations in the ionosphere. The perturbations behave as terminator wave that propagates in a northwestward direction after sunset. The pre-reversal enhancement that surprisingly occurred in its unfavorable growing season at the June solstice during solar minimum. On the other hand, the rate of TEC index (period < 5 min) indicates the occurrence of irregularities that evolve from the large or coarse structures with a period ranging from hours to dozens of minutes in the nighttime due to the eclipse. The adaptive analysis exposes the temporal and spatial evolutions of the irregularities from larger structures continuously. The effects of thermal convergence on the ionosphere can be attributed to the development of disturbances and irregularities.