Van Allen Probe observations: Poloidal ULF waves excited by resonant wave-particle interaction in the inner magnetosphere
Thursday, 4 September 2014: 9:25 AM
Regency Ballroom (Hyatt Regency)
Lei Dai1, Kazue Takahashi2, John R Wygant1, Liu Chen3,4, John W Bonnell5, Cynthia A Cattell1, Scott A Thaller1, Craig Kletzing6, Charles William Smith7, Robert J MacDowall8, Daniel N. Baker9, J Bernard Blake10, J. F. Fennell11, Seth G Claudepierre12, Herbert O Funsten13, Geoffrey D Reeves14 and Harlan Spence7, (1)University of Minnesota Twin Cities, Minneapolis, MN, United States, (2)Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, United States, (3)Univ of California - Irvine, Irvine, CA, United States, (4)ZheJiang University,, Institute for Fusion Theory and Simulation, Hangzhou, China, (5)Univ California, Berkeley, CA, United States, (6)Univ. of Iowa, Iowa City, IA, United States, (7)University of New Hampshire, Durham, NH, United States, (8)NASA Goddard SFC, Greenbelt, MD, United States, (9)University of Colorado, Laboratory for Atmospheric and Space Physics,, Boulder, CO, United States, (10)The Aerospace Corporation, Los Angeles, CA, United States, (11)The Aerospace Corp, Los Angeles, CA, United States, (12)The Aerospace Corporation, Santa Monica, CA, United States, (13)Los Alamos Natl Laboratory, Los Alamos, NM, United States, (14)Los Alamos National Laboratory, Los Alamos, NM, United States
Abstract:
Poloidal ULF waves can accelerate (or de-accelerate) particles in the magnetosphere via their azimuthal wave electric field that is aligned with particles' longitudinal drift motion. Using measurements of electric fields (EFW), magnetic fields (EMFISIS) and energetic particles (ECT) from theVan Allen Probes (RBSP) spacecraft, we clearly identify the wave harmonic mode, detect the wave-particle resonance signatures, and determine the free energy source in a event (Oct 23,2012) where a poloidal standing wave is excited by drift-resonance interaction with ring current ions. As the RBSP mission proceeds to the second year and the orbit covers more MLT in the inner magnetosphere, more poloidal wave events have been identified. We will focus on poloidal waves excited by drift and drift-bounce resonance. Multi-events study will be presented on the physical properties, the dependence on geomagnetic activity and the location, and the excitation mechanisms of poloidal ULF waves. In particular, we will present events that excitation of poloidal ULF waves appears to affect ring current in the storm recovery phase.
