Michaela Mooney

The plasmasphere plays a key role in magnetospheric dynamics, influencing the dynamics of the radiation belt, ULF wave profiles and magnetospheric convection. Conjugate observations of the undulations on the plasmapause and at the equatorward edge of the auroral oval (He et al., 2020) imply that these two boundaries are co-located. Using global plasmapause identifications from extreme ultraviolet observations, we compare the mapped ionospheric footpoints of the plasmapause identifications with the equatorward auroral boundary in all local time sectors and under different levels of geomagnetic activity. The results of this analysis show that the ionospheric footpoint of the plasmapause maps closely to the equatorward boundary of the auroral oval in the nightside sectors statistically. However, in the dayside local time sectors, there is a large (~10°) statistical offset between the two boundaries implying that the processes that limit the equatorward extent of the aurora differ on the dayside and nightside of the Earth. The upcoming SMILE mission will provide an excellent suite of both in-situ and remote sensing observations of the aurora and magnetospheric plasma environments to explore in more detail the difference in the agreement between the plasmapause and the equatorward auroral boundary in different local time sectors.