Thermospheric and ionospheric dynamics in the auroral region Original Research Article

Behavior of the thermosphere and the ionosphere in the auroral region, especially near an auroral arc, is quite complicated. There have been a number of reports on vertical neutral winds in the auroral region, suggesting that heat sources associated with local auroral activities could cause extremely large upwelling and downwelling of the thermosphere. A two-dimensional nonhydrostatic thermosphere-ionosphere model is used to study variations in the thermosphere and the ionosphere associated with a moving auroral arc. The results are compared with data obtained by the EISCAT (European Incoherent Scatter) radar measured in the vicinity of auroral arcs. The overall behavior of the observed ion motion parallel to magnetic field lines is interpreted as perturbation caused by neutral wind driven by auroral arcs. The model calculation suggests that temporal and spatial variations in the heating region significantly influence the structure of neutral and ion motion near auroral arcs.