Ionospheric, Thermospheric, Electrodynamic and Magnetic response to the annular solar eclipse of 14 October 2023: a multi-instrumental study

On 14 October 2023, an annular eclipse took place between 1503 UT and 2055 UT. It affected both North and South America. In this study, we used multiple ground-based and space-borne instruments, and we analysed ionospheric, thermospheric, magnetic and electrodynamic responses to this eclipse. In the vertical total electron content (VTEC) maps, at mid-latitudes, we observed a 40% depletion shortly after the Moon’s shadow arrival. When the eclipse reached the low latitude region and the northern crest of the equatorial anomaly, we observed only 20-25% VTEC decrease in the vicinity of the eclipse path. However, after the Moon shadow crossed the magnetic equator, the low-latitude VTEC depletion reached 40%. The latter can be explained by the eclipse weakening the equatorial electric fields and, consequently, the equatorial fountain. In the topside VTEC and in the in-situ electron density measurements from Swarm B and C satellites we observed 40-50% decrease over the area affected by the eclipse. In the thermosphere, the eclipse produced a noticeable drop in the neutral mass density (7-18%) at 490-510 km of altitude, and changed the thermospheric composition in the vicinity of the eclipse path by 25-35%. Finally, the eclipse also clearly affected the geomagnetic field, especially at low and equatorial latitudes. Shortly after the umbra’s arrival, we observed a clear decline in the total intensity F and the horizontal component H at all equatorial stations in South America. Whereas, in the variations of the vertical magnetic component Z no common pattern was observed during the eclipse. Key points:  the eclipse caused 40% depletion in total electron content, and it produced 40-50% decrease in electron density in the topside ionosphere  satellites show 7 to 20% decrease in the neutral mass density and 25-35% change in the thermospheric composition due to the eclipse  magnetic measurements show a clear decrease in the total intensity and horizontal component at low latitudes during the eclipse