JpGU-AGU Joint Meeting 2017

Presentation information

[EE] Oral

P (Space and Planetary Sciences) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM16] [EE] Physics of Inner Magnetosphere Coupling

Tue. May 23, 2017 3:30 PM - 5:00 PM A02 (Tokyo Bay Makuhari Hall)

convener:Danny Summers(Memorial University of Newfoundland), Jichun Zhang(University of New Hampshire Main Campus), Yusuke Ebihara(Research Institute for Sustainable Humanosphere, Kyoto University), Kunihiro Keika(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo ), Aleksandr Y Ukhorskiy(Johns Hopkins University Applied Physics Laboratory), Dae-Young Lee(Chungbuk Natl Univ), Yiqun Yu(Beihang University), Yoshizumi Miyoshi(Institute for Space-Earth Environmental Research, Nagoya University), Chairperson:Aleksandr Ukhorskiy(Johns Hopkins University Applied Physics Laboratory)

4:15 PM - 4:30 PM

[PEM16-16] Relativistic electron flux dropout due to field line curvature during the storm on 1 June 2013

*Suk-Bin Kang1, Mei-Ching Fok1, Mark Engebretson2, Wen Li3 (1.NASA Goddard Space Flight Center, 2.Augsburg College, 3.Boston University)

Keywords:relativistic electron dropout, loss, field line curvature

A relativistic flux dropout is a sudden and significant decrease in the relativistic electron (> 1 MeV) population of the outer radiation belt occurring over timescales of a few hours. A significant dropout of relativistic electrons was observed by Van Allen Probes during the storm main phase on June 1, 2013. During the same period, MeV electron precipitation with isotropic pitch-angle distribution was also observed from POES but no EMIC waves were detected from either space- or ground-based magnetometers. Based on Tsyganenko empirical magnetic field model, magnetic field lines are highly non-dipolar and stretched at the night side in the inner magnetosphere. This condition can break the first adiabatic invariant (conservation of magnetic moment) and generate pitch-angle scattering of relativistic electron to the loss cone. To understand the relative roles of different physical mechanisms on this dropout event, we simulate flux and phase space density of relativistic electrons with event specific plasma wave intensities using the Comprehensive Inner Magnetosphere and Ionosphere (CIMI) model. We also employ pitch-angle scattering due to field line curvature in the CIMI model. We re-configure magnetic field every minute and update electric field every 20 seconds to capture convective and diffusive radial transport. CIMI-simulation with pitch-angle scattering due to field line curvature shows more depletion of relativistic electron fluxes and better agreement to observation. We conclude that pitch-angle scattering due to field line curvature is one of the dominant processes for the relativistic electron flux dropout.