Ionospheric Responses at Low Latitudes to the Annular Solar Eclipse on 21 June 2020

Abstract

In this study, we utilized both ground-based and space-borne observations including total electron content (TEC) from Beidou geostationary satellites, two-dimensional TEC maps from the worldwide dense Global Navigation Satellite System receivers, ionosondes, and in situ electron density (Ne) and electron temperature (Te) from both Swarm and China Seismo-Electromagnetic Satellite satellites, to investigate the low-latitude ionospheric responses to the annular solar eclipse on 21 June 2020. The decrease in TEC during the eclipse at low latitudes showed a local time dependence with the largest depletions in the noon and afternoon sectors. It was also found that the TEC depletions at different latitudes in the equatorial ionization anomaly (EIA) region over the East Asian sector cannot solely be explained by the solar flux changes associated with the obscuration rate. The differences in TEC reduction between stations can be more than a factor of 2 at latitudes with the same obscuration rate of over 90%. Compared with TEC variations in the Northern Hemisphere, the TEC also underwent a considerable decrease in the EIA region in the conjugate hemisphere without eclipse shadow. Meanwhile, the h m F 2 near the magnetic equator increased around the onset of the eclipse, indicating an enhancement of the eastward equatorial electric field. Furthermore, the TEC decrease during the eclipse in the EIA region in both hemispheres lasted for a long period of more than 7 hr after the eclipse, with a TEC depletion of 2-6 TEC units. The Ne from Swarm and China Seismo-Electromagnetic Satellite satellites showed a complicated variation after the eclipse, whereas no visible change was observed in Te. The enhanced equatorial electric field, neutral wind changes, and the associated plasma transport act together to generate the observed ionospheric effects at low latitudes during the eclipse. Our results also suggest that the eclipse-induced perturbations of dynamic processes can continue to impact the ionosphere after the eclipse.

A multi-instrumental and modeling analysis of the ionospheric responses to the solar eclipse on 14 December 2020 over the Brazilian region

“…They also obtained the TEC difference, and their results showed a significant reduction around EIA regions at solar eclipse times. Huang et al (2020) studied the ionospheric responses at low latitudes in a solar eclipse on 21 June 2020. The authors also found that the EIA decreases significantly in the solar eclipse hours.…”

“…Therefore, although this solar eclipse event almost did not reach the equatorial regions, we suppose it was enough to influence the fountain effect. Also, Huang et al (2020) mentioned that during the eclipse events the transequatorial northward or southward neutral wind can weaken, causing a reduction of the EIA crests. Le et al (2009) showed an analysis of the ionosphere in the conjugate hemisphere during the solar eclipse on 3 October 2005.…”

Nighttime Ionosphere Perturbed by the Annular Solar Eclipse on June 21, 2020

“…By contrast, the positive TEC deviation appears on the southern side of the obscuration path near 87°–100°E at 0910–0920 UT (Figure 1d). The thermospheric neutral wind flowing toward the obscuration path can lead to the plasma transporting along the magmatic field line at low latitudes (Aa et al., 2021; Cheng et al., 1992; Dang et al., 2020; Huang et al., 2020; Le et al., 2010, 2020; Yeh et al., 1997; Zhang et al., 2020) which can cause the positive TEC deviation in the afternoon (Movie ).…”

Ionospheric effects of the 5–6 January 2019 eclipse over the People's Republic of China: results from oblique sounding

“…In the ionosphere, aperiodic and quasi-periodic perturbations in the electron density, N, have been detected with a 1 %-10 % amplitude and a ∼ 10 min period, T , whereas the decrease in the electron density of the ionospheric E region attains 26 %, agreeing well with the theoretical estimate (24 %). The solar eclipse of 21 June 2020 that occurred in the equatorial ionosphere was observed by Le et al (2020), Zhang et al (2020), Huang et al ( , 2021, Dang et al (2020), Patel and Singh (2021), J. Wang et al (2021), X.…”

“…Wang et al (2021), Şentürk et al (2021), Sun et al (2021), Shagimuratov et al (2021), Aa et al (2021), Chen et al (2021), andTripathi et al (2022); the ionospheric effects were observed to occur with the South Atlantic Anomaly in the background. Zhang et al (2020) detected effects from the solar eclipse in the magnetically conjugate region. Chernogor and Mylovanov (2022) describe the ionospheric effects of the annular solar eclipse of 10 June 2021 that occurred in high latitudes.…”