The contribution of plasma sheet bubbles to stormtime ring current buildup and evolution of its energy composition

Previous studies have demonstrated that a significant fraction of the total inward plasma sheet transport takes place in the form of bursty bulk flows, known theoretically as flux tube entropy-depleted "bubbles." However, it remains an open question to what extent bubbles contribute to the buildup of the stormtime ring current.

Using the Multiscale Atmosphere Geospace Environment Model, we present a case study of the 17 March 2013 storm, including a quantitative analysis of the contribution of plasma transported by bubbles to the ring current. We show that bubbles are responsible for at least 50% of the plasma energy enhancement within 6 R-E during this strong geomagnetic storm. The bubbles that penetrate within 6 R-E transport energy primarily in the form of enthalpy flux, followed by Poynting flux and relatively little as bulk kinetic flux.