The Role of Ion Injections in the Buildup of the Ring Current Pressure: A Van Allen Probes/RBSPICE study of the March 17th, 2013 Geomagnetic Storm (Invited)

The ring current is the key element of magnetic storms in the near-Earth space. The distortion of the Earth's magnetic field due to the ring current significantly affects the dynamics of the radiation belt population. Understanding the ring current dynamics itself is, therefore, essential. The transport and associated heating of the plasma from the tail into the inner magnetosphere is thought to be responsible for the ring current build up. However, there has been an ongoing debate about the extent to which this transport is due to global enhancement of the electric field and steady inward convection of energetic particles, or a result of localized injections of these particles associated with dynamic reconfigurations of the magnetic field, such as observed during magnetospheric substorms occurring during geomagnetic storms. During the main phase of the March 17th 2013 storm, the two Van Allen Probes (A and B), in equatorial orbits with apogee at L~5.8 and MLT ~1hr, cut through the ring current region for two consecutive orbits. Throughout the main phase of the storm, Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) and Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instruments, both on board Van Allen Probes, observed multiple dispersionless ion injections, and dipolarizations of the magnetic field respectively. Our analysis shows evidence of plasma pressure increases associated with these ion injections penetrating deep into the ring current region. We investigate quantitatively the contribution of injected protons, as well as injected helium and oxygen ions to the total ring current pressure. We assess the extent to which the ring current build up can be explained wholly or in part by the injected contributions.