Ionospheric, Thermospheric, Electrodynamic and Magnetic Response to the Annular Solar Eclipse of 14 October 2023: A Multi‐Instrumental Study

Abstract In this work, we used multiple ground‐based and space‐borne instruments, and we studied the ionospheric, thermospheric, magnetic and electrodynamic responses to the annular eclipse of 14 October 2023, that affected both North and South America. Based on the vertical total electron content (VTEC) maps and Swarm data sets, we observed a strong eclipse impact on the ionosphere with a 40% TEC depletion recorded at midlatitudes, likely induced by the lack of photoionization. At low‐latitudes, we observed a more complex response with only 20%–30% decrease in the VTEC and an overall weakening of the equatorial ionization anomaly (EIA). Our observations suggest that the equatorial and low‐latitude effects result from a combination of a significant decrease in the equatorial electrojet (EEJ), magnetic field intensity (mainly the X component) and vertical ion velocity as observed by ground‐based magnetic data and the JULIA radar. Besides, the eclipse also strongly impacted the thermosphere and caused a 10%–30% drop in the neutral mass density and a 25%–30% change in the O/N 2 ratio in the vicinity of the eclipse path. The observed disturbances suggest the presence of thermospheric winds converging toward the umbra region. Such winds can induce significant additional effects on the EIA electrodynamics, which we consider to be a major factor of the complex equatorial and low‐latitude response.