SAID: A turbulent plasmaspheric boundary layer

Abstract

This paper presents novel features of subauroral ion drifts (SAID) observed from a unique conjunction of the Cluster, DMSP, and Polar satellites, including the discovery of SAID‐related plasma waves. These observations confirm and expand on our proposed concept of the SAID channel being a turbulent boundary layer, formed via a short circuit of the substorm‐injected plasmoid by the plasmasphere. We show that SAID formation is related to enhanced lower hybrid/fast magnetosonic waves. Their excitation leads to anomalous circuit resistivity and magnetic diffusion, similar to the well‐documented plasmoid‐magnetic barrier problem, including impulsive penetration at the magnetopause.