Magnetospheric Multiscale Observations of Ultra Low Frequency Waves in the Inner Magnetosphere

Thursday, 17 December 2015
Poster Hall (Moscone South)
Robert J Strangeway1, Christopher T Russell2, James L Burch3, Roy B Torbert4, Werner Magnes5, Ferdinand Plaschke6, Hannes Karl Leinweber7, Kenneth R Bromund8, David Fischer6, Brian J Anderson9, Guan Le8, Mark Chutter10, James A Slavin11, Larry Kepko8, Olivier Le Contel12, Rumi Nakamura13, Wolfgang Baumjohann14, Matthew R Argall4 and Peter J Chi1, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)University of California Los Angeles, IGPP/EPSS, Los Angeles, CA, United States, (3)Southwest Research Institute, San Antonio, TX, United States, (4)University of New Hampshire Main Campus, Durham, NH, United States, (5)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (6)IWF Institute for Space Research, Graz, Austria, (7)Institute of Geophysics and Planetary Physics Los Angeles, Los Angeles, CA, United States, (8)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (9)Johns Hopkins University, Baltimore, MD, United States, (10)University of New Hampshire, Durham, NH, United States, (11)University of Michigan Ann Arbor, Ann Arbor, MI, United States, (12)Laboratoire de Physique des Plasmas (UMR7648), CNRS/Ecole Polytechnique/UPMC/Univ. Paris Sud/Obs. de Paris, Paris, France, (13)Austrian Academy of Sciences, Vienna, Austria, (14)Austrian Academy of Sciences, Graz, Austria
The apogee of the Magnetospheric Multiscale (MMS) spacecraft was in the predawn local time sector early in the MMS commissioning phase. On several orbits in this phase MMS observed large amplitude (10s of nT) Pc5 pulsations, typically around 5 to 7 Earth radii, near dawn. Because MMS was in a string-of-pearls configuration we could determine the phase velocity of the waves along the spacecraft separation vector. Preliminary analysis indicates that this was of the order 30-50 km/s, much larger than the spacecraft velocity. Furthermore, the waves are propagating tailwards. Given a nominal wave period of the order 5 minutes, the wavelength of the waves is around 2 Earth radii, assuming azimuthal propagation. This corresponds to an m-number of about 20. The waves used for this initial study were observed on several successive orbits during the recovery phase of the March 17, 2015 geomagnetic storm. We will present additional analysis of the properties of these ULF waves as observed during the MMS commissioning phase, during which time the spacecraft apogee migrated from dawn to dusk through the nightside.