Physics of auroral phenomena : proceedings of the 37th Annual seminar, Apatity, 25 - 28 February, 2014 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Изд-во Кольского научного центра РАН, 2014. - 125 с. : ил., табл.

POLOIDAL MONOCHROMATIC PULSATIONS IN THE Pc4-Pc5 RANGE OBSERVED IN THE EARTH MAGNETOSPHERE V. Belakhovsky1, V. Pilipenko2, S. Samsonov3, D. Klimushkin4, and P. Mager4 1 Polar Geophysical Institute, Apatity, Russia 2Institute o f the Earth Physics, Moscow, Russia 3Institute o f Cosmophysical Research and Aeronomy, Yakutsk, Russia 4Institute o f Solar-Terrestrial Physics, Irkutsk, Russia Abstract. In this study we examine the spatial and polarization structure of monochromatic pulsations in the Pc5 frequency range, detected by a fleet of satellites (GOES, LANL, THEMIS) in the morning sector of the magnetosphere on Sept. 09, 2007. These pulsations are excited during low geomagnetic activity. The satellite observations show that these pulsations are a poloidal-type fundamental mode of All'ven field line oscillations with small scale in the azimuthal direction 25). These pulsations practically cannot be seen on the ground CARISMA magnetometers. The observed Pc5 waves are accompanied by simultaneous pulsations of the fluxes of encrgetic electrons and protons, as seen by LANL-1994 satellite. The modulation depth in the fluxes of energetic particles is larger than the modulation depth in geomagnetic field. A several-fold increase of the electron density in the magnetosphere is found before the onset of poloidal Pc4-5 waves. As seen by THEMIS satellites, these pulsations propagate in the morning sector in the sunward direction, i.e. in the direction of electron drift. We suppose that the injection of energetic electrons may be responsible for the excitation of the poloidal Pc5 pulsations at the morning flank of the magnetosphere via the "ship wave" mechanism. 1. Introduction There are many types of ULF waves in the Earth magnetosphere, which differ by their periods (Pc3-5, Pg, Pi2-3), waveforms (broadband or monochromatic), polarization structure (poloidal, toroidal, or compressional), etc. One of the most puzzling type is the poloidal pulsations [Anderson, 1993]. In this study we try to examine this type of pulsations with new data facilities and compare observations with recent theoretical ideas. In particular, we try to answer the following questions: What is the wave mode responsible for these pulsations? Is the monochromatic wave form of these pulsations related to the occurrence of specific wave resonator? What is the driving factor of these pulsations during very a quiet period? 9 S ep tem be r 2007, 12.00 UT. •Physics o f Auroral Phenomena * Proc. XXXVII Annual Seminar, Apatity, pp. 59-62, 2014 © Kola Science Centre, Russian Academy of Science, 2014 Figure 1. The location of the GOES, LANL, and THEMIS spacecraft in XY plane of the GSM coordinate system during the event Sept. 9,2007 at 12.00 LIT. Polar Geophysical Institute 10 6 6 4 2 0 X (GSM), Re 2- Data ^he geomagnetic field data with the high time resolution (0.512 sec) from the GOES-12 (MLT=UT-5), GOES-IO (MLT=UT-4), GOES-11 (MLT=UT-9) geostationary spacecrafts was used. The particle dynamics was detected by the LANL-01 (MLT=UT), LANL-02 (MLT=UT+4.5), LANL-89, LANL-97 (UT+7), LANL-94 (MLT=UT-3.5) geostationary spacecraft. We have used the moments computed from measurements of the MPA instrument (ions ^l30eV/e - 45keV/e and electrons ~30eV - 45keV), and SOPA instrument (electrons and protons >50-75 keV). THEMIS probe data have been used for observations of the magnetic and electric field variations, and energetic Particle fluxes. CARISMA network stations are used for the registration of geomagnetic field variations in conjugate to the satellite regions. NORSTAR riometers are used for the control of the energetic electron precipitation into the 10riosphere. 59