On the relationship of the plasmapause to the equatorward boundary of the auroral oval and to the inner edge of the plasma sheet

ISEE 1 observations of the plasmapause are compared with simultaneous observations of the electron plasma sheet and also the auroral oval observed in DMSP photographs. Only a limited amount of appropriate data was available for the comparisons: the plasmapause/plasma sheet inner edge comparisons were restricted to the early and late morning sectors, while there were two satisfactory comparisons of the plasmapause and the equatorward boundary of the auroral oval in the evening sector. However, these examples indicate that the plasmapause location often coincides to within ΔL ∼ 0.1–0.2 with both the plasma sheet inner boundary and the field line threading the equatorward boundary of the auroral oval. This co‐location of the plasmapause and the plasma sheet inner edge may be due to shielding of the magnetospheric convection electric field by an Alfvén layer located at the inner edge of the plasma sheet as discussed by Jaggi and Wolf (1973) and others.