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.

V. Belakhovsky et al. 3. The event September 9, 2007 3.1. GOES geomagnetic field observations The monochromatic pulsations are well evident on the GOES-IO and GOES-12 geostationary spacecraft during ~5 hours (Fig. 2). The pulsations are stronger, up to ~8 nT, in the radial component Ae. Weaker pulsations can be seen also in the field-aligned component hv and in the module of the geomagnetic field ht. This polarization indicates on the poloidal-type transverse wave structure. Whereas these poloidal pulsations are clearly evident at near-by spacecraft GOES-IO and GOES-12 (MLT difference is ~1 h), they cannot be seen at more distant geostationary GOES-11 spacecraft, located on the night side. 9 S eptem ber 2007. GOES-IO, MLT=UT-4. 9 S ep tem b er 8007. GOES-12, MLT=UT-5. Figure 2. The magnetic field variations at GOES-IO (left-hand panel) and GOES-12 (right-hand panel) spacecraft. Magnetograms from the GOES-IO, -12 spacecraft demonstrate a very monochromatic waveform of these waves. The spectral analyze reveals a narrow spectral maximum (not shown) at/-5 .4 mHz (743 min), that is in the nominal Pc5 range. Though the poloidal pulsations are clearly evident simultaneously on both GOES-10 and GOES-12 spacecraft, the coherence between them is low. This does not enable us to determine the wave phase delay between these spacecraft. 3.2. Ground observations. The considered pulsations cannot be seen on the ground CARISMA magnetometers (not shown), even at stations near the conjugate points of the GOES-IO and GOES-12 spacecraft. This fact indicates on a small-scale transverse structure of these pulsations. 3.3. Geomagnetic activity. These pulsations are observed during a low geomagnetic activity, contrary to majority of other types of ULF waves. The SYM-H index is about -10 nT, and AE-index is -60-160 nT. According to the OMNI database, the solar wind speed is V = 380 km/s, and density is N ~ 4 cm'3. Just before the onset of these pulsations, the AE-index has increased from -30 nT to -80 nT. We suppose that the source of these pulsations is associated with local processes inside the magnetosphere. 3.4. LANL energetic particles observations. The considered pulsations are accompanied by simultaneous pulsations in the fluxes of energetic electrons and protons (Fig. 3) with the same period, as seen from the observations on LANL-1994 geostationary spacecraft. The GOES-IO and LANL-1994 spacecraft are located close to each other (Fig. 1). At the same time no periodic pulsations are observed in the riometer data from the NORSTAR network. The modulation depth (ratio of the pulsation amplitude to the background level) for the proton fluxes reaches AJp/Jp - 60% (in the 50-75 keV energy channel). The modulation depth in electron fluxes is lower, AJe/Je « 12%. Surprisingly, the modulation depth of the magnetic variations is lower than that of particles, Aht/ht = 1.3%, and Ahe/he ~ 10%. Thus, the AJe/Je and Ahe/he are quite comparable, but AJp/Jp » Ahe/he. 60