Multi-Spacecraft MMS Observations of Dawn Flank Pc5 Waves

Plaschke, Ferdinand

Multi-Spacecraft MMS Observations of Dawn Flank Pc5 Waves

Thursday, October 1, 2015

Ferdinand Plaschke¹, Rumi Nakamura¹, Wolfgang Baumjohann¹, Werner Magnes¹, David Fischer¹, Roy B Torbert^2,3, Christopher T Russell⁴, Robert J Strangeway⁴, Hannes Karl Leinweber⁴, Kenneth R Bromund⁵, Brian J Anderson⁶, Guan Le⁵, Mark Chutter², James A Slavin⁷, Larry Kepko⁵ and Olivier Le Contel⁸, (1)Space Research Institute, Austrian Academy of Sciences, Graz, Austria, (2)University of New Hampshire, Durham, NH, United States, (3)Southwest Research Institute San Antonio, San Antonio, TX, United States, (4)University of California Los Angeles, Los Angeles, CA, United States, (5)NASA/GSFC, Greenbelt, MD, United States, (6)JHU/APL, Laurel, MD, United States, (7)University of Michigan, Ann Arbor, MI, United States, (8)Laboratoire de Physique des Plasmas, Paris, France

Abstract:

On March 12, 2015, the four Magnetospheric Multi-Scale (MMS) spacecraft were launched into a common, equatorial, highly elliptical orbit around Earth. The apogee was located in the early morning sector. Along their common orbit, the MMS spacecraft were travelling in a so-called string-of-pearls configuration, with inter-spacecraft distances in the 100 – 1000km range. In that configuration, the spacecraft traversed the dawn terminator on the inbound leg, about once per day.
In that region, the spacecraft often (but not always) observed clear, high amplitude toroidal Alfvén waves with periods of a few minutes (in the Pc5 range) that may be interpreted as dawn flank field-line resonances. The special configuration of the spacecraft give us the unique opportunity to study, with in-situ multi-spacecraft measurements, the onset of these waves, i.e., driving and local energy conversion from compressional waves, as well as temporal versus spatial phase variations, including propagation characteristics. We present case study results in the context of other spacecraft and ground observations.