Effects of geographic-geomagnetic pole offset on ionospheric outflow: Can the ionosphere wag the magnetospheric tail?

Abstract

The generalized polar wind model was used to simulate the polar ionosphere during the September/October 2002 storm. The solar terminator moved across the polar caps in a diurnal oscillation during this equinox period. The main conclusions of this study are the following: (1) the terminator oscillation generates a diurnal oscillation in the total hemispheric fluxes of the polar wind from the ionosphere into the magnetosphere; (2) the diurnal oscillation of outflow in the Northern Hemisphere is 12 h out of phase with the Southern Hemisphere; (3) the H+ outflow flux is near its limiting value, so the oscillation is larger than the nonperiodic contributions (e.g., geomagnetic activity); and (4) the O+ flux is less than its limiting value, hence the diurnal oscillation is comparable to the non-periodic effects. The simulation suggests that the hemispherical asymmetry and periodicity of the total ion outflow could "wag the magnetospheric tail" and perhaps contribute to substorm triggering. Key Points The hemispheric integrated outflow fluxes have an oppositely phased diurnal oscillation The hemispheric integrated H+ outflow is dominated by the diurnal oscillation The hemispheric integrated O+ outflow also has a component associated with geomagnetic activity