Diagnosing the Role of Alfvén Waves in Global Field‐Aligned Current System Dynamics During Southward IMF: Swarm Observations

Field‐aligned currents (FACs) are a primary signature of magnetosphere‐ionosphere coupling (MIC). However, establishing FACs requires the propagation of Alfvén waves. Large‐scale quasi‐static FACs are well‐organized into large‐scale Region 1 (R1) and Region 2 (R2) systems during intervals of southward interplanetary magnetic field (IMF); however, the scale‐dependent spatiotemporal variability and related electrodynamics are less well understood....