Latitudinal and hemispheric responses of solar quiet ionospheric currents during two annular solar eclipses: evidence from low to mid-latitude observations
A sudden drop in solar radiation during an annular (or total) eclipse directly affects ionospheric electrodynamics, primarily through the reduction of solar extreme ultraviolet (EUV) and soft X-ray flux, which are responsible for generating the ionospheric plasma. The annular solar eclipses of 21 Ju...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad de Alcalá (UAH) |
| Repositorio: | e_Buah Biblioteca Digital Universidad de Alcalá |
| Idioma: | inglés |
| OAI Identifier: | oai:dnet:ebuahbibliot::171e87dd044f979cccb59d15a0ac20ac |
| Acceso en línea: | http://hdl.handle.net/10017/69111 https://dx.doi.org/10.1029/2025JA034761 |
| Access Level: | acceso abierto |
| Palabra clave: | Física Astronomía Physics Astronomy |
| Sumario: | A sudden drop in solar radiation during an annular (or total) eclipse directly affects ionospheric electrodynamics, primarily through the reduction of solar extreme ultraviolet (EUV) and soft X-ray flux, which are responsible for generating the ionospheric plasma. The annular solar eclipses of 21 June 2020 and 14 October 2023 offer natural experiments under markedly different solar conditions. The 2020 eclipse occurred during a period of low solar activity (F10.7 = 70 s.f.u., Kp < 1), while the 2023 eclipse took place under higher solar activity levels (F10.7 = 147.4 s.f.u., Kp < 3), leading to stronger background solar-quiet (Sq) ionospheric current and more pronounced electrodynamic responses. Using global geomagnetic records from SuperMAG and coordinated networks, the Sq current and eastward current densities (Je) are estimated via spherical harmonic analysis techniques. The equatorial and low-latitude horizontal geomagnetic field variation (ΔH) decreased near maximum obscuration, with larger depletion in 2023 than in 2020, and smaller variations in the conjugate hemisphere. Concurrently, Je weakened by ∼15% (2020) and ∼25% (2023), while the equatorial electrojet (EEJ) changed 10%–30% with local-time phase shifts; the 2020 eclipse featured a transient EEJ enhancement, whereas 2023 showed suppression followed by delayed recovery. Maximum northern Sq current values decreased ∼20% and southern minima ∼13% in the 2020 eclipse, while the 2023 Sq current was ∼65% stronger. The largest separation between northern and southern Sq current foci occurred during 2020 (∼2 h, ∼30° longitude; ∼5° latitude at 30°N and 35°S), whereas the 2023 eclipse exhibited smaller longitudinal (∼1 h, ∼15° longitude) but larger latitudinal (∼15°, 30°N and 45°S) offsets. |
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