THE FEATURE OF THE IONOSPHERE IN THE AURORAL ZONE AND THE MAGNETOSPHERE- IONOSPHERE COUPLING

Four cases are investigated by using EISCATdata. It is shown that the magnetosphere-ionosphere coupling significantly influences the auroral ionospheric morphology. During the magnetic storm, the enhancement of the convection electric field and the particle precipitation could make the electron density of the Eregion much larger than that of the F-region, and the vertical profile deviates from the normal distribution completely. The solar radiation is not the only factor controlling the day-night and annual variation of the ionospheric electron density even in the magnetic quiet periods. The plasma drift caused by the magnetospheric process plays an important role, especially in winter.