The Relationship between Large-Scale Field-Aligned Currents and Auroral Particle Precipitation at Different Energy Levels Based on DMSP Observations

In this study, we investigated the relationship between large-scale field-aligned currents (LSFACs) and simultaneous auroral particle precipitation using observations from the Defense Meteorological Satellites Program (DMSP). The dataset spans five years, from 1 January 2010 to 31 December 2014. Unlike previous studies that relied on the total flux, we analyzed auroral particle precipitation data measured separately by the 19 channels of the SSJ5 sensor to further investigate their relationship with typical Region 1 (R1) and Region 2 (R2) of large-scale FACs (LSFACs). Our results show that on the dusk-side, the central location of electron precipitation for the 19 channels cover the R1 FACs (upward). Specifically, the precipitation central location for 330 eV–440 eV electrons coincide with the R1 current central location. On the dawn-side, however, electron precipitation covers both R1 and R2 currents. We attribute this discrepancy to the different type of electron precipitation on the dusk- and dawn-side. Dusk-side electron precipitation is dominated by discrete aurora produced by parallel electric field acceleration, which is typically considered to be directly associated with FACs. And dawn-side electron precipitation is dominated by diffuse aurora, which we suggest does not directly generate LSFACs. The central locations of ion precipitation are roughly consistent on both the dawn and dusk sides, concentrating within the R1 FACs. Since R1 currents are upward on the dusk-side and downward on the dawn-side, this finding further demonstrates that ion precipitation is not directly related to LSFACs.