SM24B-08
Formation of Inner Magnetospheric Energetic Electron Butterfly Distributions by Equatorial Magnetosonic Waves
Tuesday, 15 December 2015: 17:45
2018 (Moscone West)
Jinxing Li1, Binbin Ni1, Qianli Ma1, Lun Xie2, Zuyin Pu2, Suiyan Fu3, Jacob Bortnik1, Richard M Thorne1, Lunjin Chen4, Wen Li1, Daniel N. Baker5, Craig Kletzing6, William S Kurth6, George B Hospodarsky6, J. F. Fennell7, Geoffrey D Reeves8, Harlan E. Spence9 and Herbert O Funsten10, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)Peking University, Beijing, China, (3)Peking University, School of Earth and Space Sciences, Beijing, China, (4)University of Texas at Dallas, Richardson, TX, United States, (5)University of Colorado at Boulder, Boulder, CO, United States, (6)University of Iowa, Iowa City, IA, United States, (7)The Aerospace Corporation, Space Science Applications Laboratory, Los Angeles, CA, United States, (8)Los Alamos National Laboratory, Los Alamos, NM, United States, (9)University of New Hampshire Main Campus, Space Science Center, Durham, NH, United States, (10)Los Alamos Natl Laboratory, Los Alamos, NM, United States
Abstract:
Earth’s electron radiation belts are comprised of two distinct zones of trapped energetic electrons, separated by a ‘slot’ region. Responding uniquely to various magnetospheric processes, radiation belt electrons can exhibit different types of pitch angle distributions. Butterfly distributions, characterized by flux minima at pitch angles around 90º, are broadly observed in both the outer and inner belts and the slot region. Butterfly distributions close to the outer magnetospheric boundary have been attributed to drift shell splitting and losses to the magnetopause, however, its occurrence in other regions of the radiation belts has hitherto not been resolved. By analyzing the particle and wave data collected by the Van Allen Probes, we combine test particle calculations and Fokker-Planck simulations to reveal that scattering by equatorial magnetosonic waves is a significant cause for the formation of energetic electron butterfly distributions in the inner region of the magnetosphere. The recent March 17, 2015 storm show the creation of butterfly distributions of electrons up to 4 MeV under the impact of magnetosonic waves.
