Large-Scale Field-Aligned Currents Around the High-Latitude Energetic Electron Boundary: FY-3E Observations

Abstract

The recently launched Fengyun-3E (FY-3E) satellite in the early morning orbit can simultaneously measure magnetic fields and energetic electrons, which provides a good opportunity to investigate the distribution and variation of large-scale field-aligned currents (FACs) in the dawnside and duskside of both hemispheres. Based on the statistical results with one and a half years of data, we find that the location of region 1 (R1) and region 2 (R2) currents is closely associated with the high-latitude energetic electron boundary, these FACs in the northern hemisphere are preferentially located in higher magnetic latitudes than in the southern hemisphere especially during geomagnetic quiet time, and the location of FACs has a larger equatorward motion than the electron boundary during active time. The location and current intensity of FACs in different sectors of Earth's magnetosphere are quantified as a function of the Kp index, the Sym-H index and the interplanetary magnetic field (IMF) $B_z$. Comparisons between different sectors also indicate that the current intensities of both R1 and R2 currents have a north-south asymmetry, and they are stronger in the dawnside northern hemisphere than other sectors. These findings may shed new light on our understanding of the spatial distribution and evolution of large-scale FACs in Earth's magnetosphere.