Altitudinal comparison of dayside field‐aligned current signatures by Viking and DMSP‐F7: Intermediate‐scale field‐aligned current systems

摘要: Dayside large-scale and intermediate-scale field-aligned current (FAC) signatures are examined with multi-instrument measurements from Viking DMSP-F7 at magnetic conjunctions. The present paper reports four such conjunction events, an emphasis on event that occurred October 13, 1986. In these events both crossed prenoon FAC systems approximately along meridians. altitude of was 835 km, whereas ranged 8500 to 12,000 km. electric field ratio measured by indicates systems, as well often quasi-stationary. This is also supported the comparison between measurements. only obvious exception equatorward part 13 event, in which better explained terms Alfven waves. two other signature projected significantly more structured than signature, although observed suggests associated FACs were quasistationary. apparent discrepancy possibly ascribed fact stays longer therefore has chance observe temporal changes FACs. However, effects must operate transit time so become Although generation mechanism(s) remains open question, possibilities include a localized shear plasma convection merging solar wind magnetospheric lines.