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 1:45 PM - 3:15 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:Danny Summers(Memorial University of Newfoundland)

2:30 PM - 2:45 PM

[PEM16-10] Rapid Variations of Energetic Electron Pitch Angle Distributions and Associated Wave Emissions

*James L Roeder1, Joseph F. Fennell1, David Schriver2, Nicole Echterling2 (1.The Aerospace Corporation, Los Angeles, CA USA, 2.University of California, Los Angeles, CA USA)

Keywords:Plasma waves, Energetic electrons, Substorm particle injections

Injections of energetic electrons into the inner magnetosphere are a common feature of spacecraft observations. The electron flux rises very rapidly and then recovers smoothly to the pre-event level over a period of several hours. Recent high resolution angular measurements by the Magnetic Electron and Ion Spectrometer (MagEIS) instrument on the Van Allen Probes have observed rapid variations in the recovery of the electron pitch angle distributions at energies in range 20-100 keV. These features can take several forms, one of which is peaks in narrow ranges of pitch angle that occur quasiperiodically every few minutes. In many cases, these electron flux bursts appear to correlate with simultaneously detected plasma wave emissions. Fennell et al. [J. Geophys. Res., 2014] reported one such event in which several flux bursts were highly correlated with upper band whistler-mode chorus waves. One difficulty with identifying and cataloging these events is the obscuration of the rapid variations by the slow trends of the background plasma. Algorithms are being developed to detrend the electron flux by subtracting out this slowly varying background and revealing the rapid burst features. Use of this procedure shows that the rapid variations in pitch angle distributions are a common feature of substorm-generated electron injections in the inner magnetosphere. Over 400 such events have been identified with more 3000 individual pitch angle featured detected. The characteristics of the bursts and associated waves are being cataloged, including the energy and pitch angle of the electron bursts, the anisotropy of the background plasma, the wave frequency and mode, the observation location, and the geomagnetic conditions during the events.