Which is a significant contributor for outside of the plasmapause, an ionospheric filling or a leakage of plasmaspheric materials?: Comparison of He II (304 Å) images

The EUV imagery of the plasmasphere was taken by the He II (304 Å) scanner on 20–21 September 1998 after the first success on 9–10 September Nakamura et al. , 2000 . Total amount of the plasma seen in the outside of the plasmapause is inconsistent between the first and the second images, although geomagnetic and solar conditions are almost the same. These plasmas are directly filled from the ionosphere or continuously leak from the plasmasphere. We conclude that the contribution of the plasma leakage from the plasmasphere is as significant as the contribution of the direct filling from the ionosphere even under a quiet/moderate geomagnetic condition.