Modelling seasonal and diurnal effects on the magnetospheric and ionospheric plasma dynamics

The diurnal variations induced by the tilt of the dipole axis are of the same order of magnitude, 5.5-29% for the Pedersen conductances and FAC and 0.4–7.1% for the magnetospheric plasma. They modulate the interhemispheric asymmetry of the FAC by 26–59%. The eccentric dipole induces an increase (decrease) of the daily variations of the conductances and the FAC by a factor 1.2-2.3 in the Southern (Northern) Hemisphere, irrespective of the season, which contributes to increase the asymmetry between the two hemispheres.

This results in an increase of the daily variations of the ion maximum pressure and of the electron maximum energy flux at the December solstice and at the March and September equinoxes, but a decrease at the June solstice. The maximal variation of the magnetospheric plasma distribution amounts to 6.7% at December solstice. These results underline the importance of considering the three different effects at the same time.