Abstract

Modeling the ionosphere during disturbed periods is one of the most challenging tasks due to the complexity of the phenomena that affect the electric fields and the whole thermosphere environment. It is well known that both, prompt penetration electric fields and large amounts of energy deposited in the polar region during disturbed periods, produce significant disturbances in the global electron density distribution, in particular, in the equatorial ionization anomaly development. Besides, the disturbance dynamo, traveling atmospheric disturbances, and traveling ionospheric disturbances also affect the equatorial ionization anomaly density distribution. In this work we use the Sheffield University Plasmasphere-Ionosphere Model at Instituto Nacional de Pesquisas Espaciais, to simulate the drastic effects that were observed at the low-latitude ionosphere in the Brazilian region during a very intense magnetic storm event, the so-called 2003 Halloween storms. In the absence of measured vertical drift during the storm, a new vertical drift deduced from the interplanetary electric field combined with the time variation of the F region virtual height is used as input. The simulation results showed that, in the case of the disturbed thermospheric wind, the ionospheric observations are better explained when a novel traveling wave-like disturbance propagating from north to south, at a velocity equal to 300 m/s, is considered.