Global Evolution, Energetics, and Origins of Auroral Streamers

Abstract

An auroral streamer—a usually meridionally aligned, arc-like feature that extend across the auroral oval. We performed a high-resolution global magnetohydrodynamic simulation to characterize the evolution of streamers and their coupling to magnetotail drivers. The results show that streamers, which are a consequence of magnetotail flow bursts, strengthen as the simulation progresses. We calculated the contributions of different precipitating electron energy fluxes to streamer dynamics based on simple empirical proxies and found that monoenergetic precipitation dominates, followed by broadband, with little from diffuse precipitation. Poleward motion (∼1° magnetic latitude) of one streamer preceded its equatorward motion in the high-resolution simulation. The simulation indicates that the poleward motion is caused by a sequential energy injection into the ionosphere from multiple bursty bulk flows propagating in succession. Our results provide an explanation for the poleward propagation of streamers and illustrate their global evolution and energetics in magnetotail dynamics.