SM41C-2495
Storm- Time Dynamics of Ring Current Protons: Implications for the Long-Term Energy Budget in the Inner Magnetosphere.
Thursday, 17 December 2015
Poster Hall (Moscone South)
Matina Gkioulidou1, Aleksandr Y Ukhorskiy1, Donald G Mitchell2 and Louis J Lanzerotti3, (1)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (2)JHU/APL, Laurel, MD, United States, (3)New Jersey Institute of Technology, Edison, NJ, United States
Abstract:
The ring current energy budget plays a key role in the global electrodynamics of Earth’s space environment. Pressure gradients developed in the inner magnetosphere can shield the near-Earth region from solar wind-induced electric fields. The distortion of Earth’s magnetic field due to the ring current affects the dynamics of particles contributing both to the ring current and radiation belts. Therefore, understanding the long-term evolution of the inner magnetosphere energy content is essential. We have investigated the evolution of ring current proton pressure (7 - 600 keV) in the inner magnetosphere based on data from the Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument aboard Van Allen Probe B throughout the year 2013. We find that although the low-energy component of the protons (< 80 keV) is governed by convective timescales and is very well correlated with the Dst index, the high-energy component (>100 keV) varies on much longer timescales and shows either no or anti-correlation with the Dst index. Interestingly, the contributions of the high- and low-energy protons to the total energy content are comparable. Our results indicate that the proton dynamics, and as a consequence the total energy budget in the inner magnetosphere (inside geosynchronous orbit), is not strictly controlled by storm-time timescales as those are defined by the Dst index.