SM41H-2572
Multisatellite Observations of Long-lasting Poloidal Pc 4 Pulsations in the Dayside Magnetosphere.
Thursday, 17 December 2015
Poster Hall (Moscone South)
David G Sibeck1, Galina Ivanovna Korotova2, Mark J. Engebretson3, John R Wygant4 and Scott A Thaller4, (1)NASA/GSFC, Greenbelt, MD, United States, (2)University of Maryland College Park, College Park, MD, United States, (3)Augsburg College, Minneapolis, MN, United States, (4)University of Minnesota Twin Cities, Minneapolis, MN, United States
Abstract:
We use magnetic field, plasma and particles observations from Van Allen Probes and THEMIS spacecraft to study the characteristics of long-lasting poloidal Pc4 pulsations in the dayside magnetosphere. They were observed after the main phase of a strong storm during low geomagnetic activity. The Pc 4 pulsations exhibited periods of 40-50 s and amplitudes of 4-6 nT in the dominant radial component. They had a packet-like structure and lasted more than 3 hours. The FFT spectra show that the main spectral power corresponds to frequencies of ~ 20-22 mHz, which argues against a source for the pulsations in the solar wind. The frequencies of the central power peak in the radial component decrease with radial distance from the Earth. The most striking feature of the Pc 4 pulsations was their occurrence at similar locations on three of four successive orbits of Van Allen Probes nine hours apart. We determined that the pulsations were second harmonic mode waves. We test various possible mechanisms for their generation.
