Global MHD Test Particle Simulations of >10 MeV Radiation Belt Electrons During Sudden Storm Commencement.

摘要

Prior to 2003, there are two known cases where ultrarelativistic (> or approx. 10MeV) electrons appeared in the Earth's inner zone radiation belts in association with high speed interplanetary shocks: the 24 March 1991 and the less well-studied 21 February 1994 storms. During the March 1991 event electrons were injected well into the inner zone on a timescale of minutes, producing a new stably trapped radiation belt population that persisted for approx. 10 years. More recently, at the end of solar cycle 23, a number of violent geomagnetic disturbances resulted in large variations in ultrarelativistic electrons in the inner zone, indicating that these events are less rare than previously thought. Here we present results from a numerical study of shock- induced transport and energization of outer zone electrons in the 1-7 MeV range, resulting in a newly formed 10-20 MeV electron belt near L approx. 3. Test particle trajectories are followed in time-dependent fields from an MHD magnetospheric model simulation of the 29 October storm sudden commencement.