A Numerical Investigation of Equatorial Ionospheric Radial Currents During the Total Solar Eclipse on 29 March 2006

Abstract

The solar eclipse is a common phenomenon, which produces significant disturbances in the ionosphere. Based on the CHAllenging Minisatellite Payload (CHAMP) observations and the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulations, this work first investigates the responses of the Ionospheric Radial Currents (IRC) to the total solar eclipse on 29 March 2006. During the solar eclipse, IRC significantly enhanced inward. The intensity increased from −0.55 nA/m² at pre-eclipse to −3.97 nA/m² at eclipse, and ultimately recovered to −0.96 nA/m², yielding a structure similar to letter “V.” The TIEGCM simulations show that the inward IRC disturbance (ΔIRC) was dominated by the dynamo current (ΔDyn). During the eclipse period, the neutral temperature in the eclipse path was significantly decreased by the sunlight shadow. Above the dip equator, a westward local wind was generated, driving the F-layer dynamo and enhancing the inward ΔDyn. The inward ΔDyn at F-layer could separate the charged particles and generate the outward polarization electric field (${\Delta E}_z$). This outward ${\Delta E}_z$ fed back to drive an outward polarization current (ΔPoL), modulating the density of ΔIRC. In addition, the Pedersen conductivity was suppressed by the upward movement of plasma at the dip equator owing to the disturbed northward winds.