Global convection in Earth's middle-to-inner magnetosphere; an outstanding mystery targeted by the Radiation Belt Storm Probes (RBSP) mission

Because of their influence on plasma populations that host and grow various plasma waves, the configuration and dynamics of the large-scale electric fields in Earth's middle-to-inner magnetosphere are critical aspects of how the radiation belt populations respond to interplanetary drivers. A standard scenario incorporated into both past and many modern simulations of inner magnetospheric behaviors is that, during such active conditions as geomagnetic storms, more distant plasma sheet populations are transported into the middle and inner magnetosphere in conjunction with strong enhancement of large-scale global "convective" electric fields. The transported populations are energized as a consequence of the invariance of the adiabatic invariants of gyration and bounce. Here we review several lines of evidence that suggest that this scenario is highly misleading. Rather, it appears that localized and transient processes overwhelmingly dominate the transport, and global convection serves to redistribute the injected particles. From the perspective of conventional wisdom, the behavior of these electric fields is highly mysterious, and thus is among the most important targets of the Radiation Belt Storm Probes (RBSP) mission.