Early main-phase electrodynamics of the ring current inferred from DMSP

Abstract

This paper exploits capabilities implicit in DMSP plasma and field data through which users may infer local IGRF magnetic fields (B→0), as well as components of magnetic perturbations (δB→⊥) and plasma drift (V→⊥) vectors perpendicular toB→0. We use relations between V→⊥ andδB→⊥, associated with Region 2 (R-2) field-aligned currents (FACs), consistent with Faraday's law, to determine Alfvénic reflection coefficients (α). Early main-phase measurements from three DMSP satellites, F16, F17 and F18 during the 17 March 2015 storm confirm the predicted V→⊥ andδB→⊥relationships. Data also show that high-latitude limits of R-2 FACs lie close to the equatorward boundaries of precipitating auroral electrons. Measurable fluxes of down-coming, ring-current ions are restricted to the vicinity of this auroral boundary. It thus remains an open question as to what particle population is responsible for carrying the downward FACs (j||) and Poynting fluxes (S||), inferred fromδB→⊥measurements acquired over the full latitudinal ranges of storm-time R-2.