SM41E-2525
The Evolution of Ring Current Energy Density and Energy Content during Geomagnetic Storms Based on Van Allen Probes Measurements
Thursday, 17 December 2015
Poster Hall (Moscone South)
Hong Zhao1, Xinlin Li2, Daniel N. Baker3, Seth G Claudepierre4, J. F. Fennell5, J Bernard Blake4, Brian Larsen6, Ruth M Skoug7, Herbert O Funsten8, Reiner H W Freidel8, Geoffrey D Reeves9, Harlan E. Spence10, Donald G Mitchell11, Louis J Lanzerotti12 and Juan V Rodriguez3, (1)University of Colorado at Boulder, LASP and Aerospace Engineering Sciences, Boulder, CO, United States, (2)Univ Colorado at Boulder, Boulder, CO, United States, (3)University of Colorado at Boulder, Boulder, CO, United States, (4)Aerospace Corporation Santa Monica, Santa Monica, CA, United States, (5)Aerospace Corporation Los Angeles, Los Angeles, CA, United States, (6)The New Mexico Consortium, Los Alamos, NM, United States, (7)Los Alamos Natl Lab, Los Alamos, NM, United States, (8)Los Alamos Natl Laboratory, Los Alamos, NM, United States, (9)Los Alamos National Laboratory, Los Alamos, NM, United States, (10)University of New Hampshire Main Campus, Space Science Center, Durham, NH, United States, (11)JHU/APL, Laurel, MD, United States, (12)New Jersey Institute of Technology, Edison, NJ, United States
Abstract:
Enabled by the comprehensive measurements from the MagEIS, HOPE, and RBSPICE instruments onboard Van Allen Probes in the heart of the radiation belt, the relative contributions of particles with different energies and species to the ring current energy density and their dependence on the geomagnetic storms and storm phases are quantified. During the main phases of moderate storms (with minimum Dst between -50 nT and -100 nT), ions of energies < 50 keV and electrons of energies of <35 keV contribute more significantly to the ring current energy than those of higher energies. During the recovery phase and quiet times higher energy protons dominate the ring current energy content. For the March 29, 2013 moderate storm, the contribution from O+ is ~25% of the ring current energy content during the main phase, and the majority of that comes from < 50 keV O+. This indicates that even during moderate geomagnetic storms the ionosphere is still an important contributor to the ring current ions and low energy O+ plays an important role in ring current dynamics. The contribution of electrons to the ring current energy content is up to ~7% during this moderate storm and the magnetic local time dependence of electron energy density is also investigated. However, the ring current energy partitions for different species and energy ranges are very different during the great storm of 17 March 2015 (with minimum Dst<-210 nT).
