On Energetic Electron Precipitation in Auroral Arcs

Abstract A key element of magnetosphere‐ionosphere coupling is the precipitation of electrons, which transfers energy from the collisionless, rarefied magnetospheric plasma into the dense, collisional ionosphere. Two distinct types of such precipitation are: auroral electrons, which carry field‐aligned currents and are responsible for auroral arc formation, and energetic electrons, which contribute to ionization in the lower ionosphere. Although these two electron populations are well separated in energy, this study reveals a close connection between them, likely due to the collocation of their equatorial drivers. Using low‐Earth orbit satellite measurements from Electron Losses and Fields Investigation of energetic (50–1,000 keV) electron precipitation and ground‐based all‐sky imager observations of auroral arcs, we demonstrate how the auroral arc structures and locations strongly correlate with the boundaries or gradients of keV precipitation. We identify three typical correlation patterns and discuss their implications for the physics of magnetosphere‐ionosphere coupling.