SM41H-2570
Multifrequency Compressional Magnetic Field Oscillations and Their Relation to Multiharmonic Toroidal Standing Alfvén Waves
Thursday, 17 December 2015
Poster Hall (Moscone South)
Kazue Takahashi1, Colin L Waters2, Craig Kletzing3, William S Kurth3, Charles William Smith4 and Karl-Heinz Glassmeier5, (1)Applied Physics Laboratory Johns Hopkins, Laurel, MD, United States, (2)University of Newcastle, Callaghan, Australia, (3)University of Iowa, Iowa City, IA, United States, (4)University of New Hampshire, Durham, NH, United States, (5)Technical University of Braunschweig, Braunschweig, Germany
Abstract:
The power spectrum of the compressional component of magnetic field observed by the Van Allen Probes spacecraft near the magnetospheric equator in the dayside plasmasphere sometimes exhibits regularly spaced multiple peaks at frequencies below 50 mHz. We show by detailed analysis of events observed on two separate days in early 2014 that the frequencies change smoothly with the radial distance of the spacecraft and appear at or very near the frequencies of the odd harmonics of mutiharmonic toroidal standing Alfvén waves seen in the azimuthal component of the magnetic field. Even though the compressional component had low amplitude on one of the selected days, its spectral properties are highlighted by computing the ratio of the spectral powers of time series data obtained from spatially separated two Van Allen Probes spacecraft. The spectral similarity of the compressional and azimuthal components suggests that the compressional component contain field line resonance characteristics.
