Observations of Electromagnetic Ion Cyclotron (EMIC) Waves with Rising Tones During a Van Allen Probes Conjunction

0518079 - ÚFA 2020 US eng A - Abstract
Sigsbee, K. - Kletzing, C. - Faden, J. - Jaynes, A.N. - Geoffrey, R. - Jahn, J. - Santolík, Ondřej
Observations of Electromagnetic Ion Cyclotron (EMIC) Waves with Rising Tones During a Van Allen Probes Conjunction.
AGU Fall Meeting. Washington: American Geophysical Union, 2019. SM23C-3221.
[AGU Fall Meeting 2019. 09.12.2019-13.12.2019, San Francisco]
Institutional support: RVO:68378289
Keywords : magnetosphere * geomagnetic storm * electromagnetic ion cyclotron (EMIC) waves * coronal mass ejections (CMEs) * solar wind * Van Allen Probes
OECD category: Fluids and plasma physics (including surface physics)
https://agu.confex.com/agu/fm19/meetingapp.cgi/Paper/493204

We will present simultaneous Van Allen Probes observations of electromagnetic ion cyclotron (EMIC) waves associated with enhanced solar wind dynamic pressure from the recovery phase of a geomagnetic storm driven by coronal mass ejections (CMEs) in December 2015. Both of the Van Allen Probes observed H+ band EMIC waves with similar spatial structures and amplitudes of a few nT during a close conjunction in the dayside magnetosphere. The EMIC waves were observed just outside the plasmasphere, within a few degrees magnetic latitude of the equatorial plane. On the outbound halves of the spacecraft orbits, the EMIC waves were observed beween 10-11 MLT in a narrow L shell region from 4.6-5.3 RE. On the inbound halves of the spacecraft orbits, the EMIC waves were observed between 13-14 MLT between L shells of 4.8-5.1 RE. The EMIC waves were associated with strong anisotropy of the proton pitch angle distributions above the Alfvén energy, which was likely caused by the high solar wind dynamic pressure and injections of ions above 10 keV. The global radiation belt response during this storm appears to have been the result of acceleration and transport processes. However, the EMIC waves still produced local pitch angle scattering of 10-15 keV protons and 2.1-2.6 MeV electrons. The EMIC waves observed by the Van Allen Probes included rising tones, which are sometimes called triggered emissions. EMIC waves with rising tones are thought to be more effective at scattering protons and electrons than unstructured EMIC waves. We will present wave normal analysis of the EMIC waves observed by both spacecraft and discuss the frequency sweep rates of the rising tones.
Permanent Link: http://hdl.handle.net/11104/0303271