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.

Т V. Kozelova and В V. Kozelov on equatorial GSM plane. Current vectors directed to the left (right) corresponds to westward (eastward) current djw ( djii). One can see that during the structure A the increased westward current djw was located at r ~ 4-5 Re. During structures В and С the increased eastward current djE was located firstly at r ~ 4 Re and then - at r ~ 5-7 Re. The main peculiarity of this interval was occurrence of prevail radial component of the perturbation current directed from the Earth. For the meridional components Jx <0 and £x>0, therefore (Jx* Ex)< 0. So, during the explosive stretching these components were directed as in a generator of three-dimensional meridional current system (MCS) of type В in the post-midnight sector of the magnetosphere [Bostrom, 1964]. This is a new experimental result. 5. Conclusions After sharp northward turning of IMF, the quick magnetic field line stretching and narrow non-dispersed 2-10 keV ion structure were observed at the morning sector of the magnetosphere implying a local impulsive acceleration appearance. Then, after ~2 min, the large-scale dipolarization and the EDIS at L ~ 8.6 were observed simultaneously with long-period magnetic pulsations at ground-based stations. No significant expansion phase activity occurred during this period probably because of short growth phase duration < 30 min. Note that usually the northward change of IMF triggers the expansion phase onset after > 3 0 min of southward IMF [Samson and Yeung, 1986]. Further, ten minutes after northward IMF turning, the pseudo-breakup and injection of higher-energy ions occur at restricted (localized) part of the evening sector (22.7 MLT). Note, that the IMF changes from Bz = -3 nT to Bz = -1 nT (from the moment 1 to the moment 5) reduces the dawn-to-dusk component of the electric field across the tail. This IMF change might be considered as a possible substorm trigger [Lyons et al., 1995]. Mishin et al. [1992], and Lazutin et al. [1998] reported that the substorm active phase often consists of two separate phases, active-convective and expansion. During the active-convective phase the loading process is still strong and comparable with the unloading of energy, while during the expansion phase the unloading becomes the main process. The event on January 6, 2008, seem to present active-convective phase [Mishin et al., 1992, and Lazutin et al., 1998,] or by other words a spontaneous- stimulated substorm [Kozelova et al., 1989]. Acknowledgements. The work was supported by the Program No 22 of the Presidium of the Russian Academy of Sciences (RAS). References Bostrom, R. (1964) A model of the auroral electrojets, J.Geophys. Res., 69(23), 4983- 4999. Kozelova Т., B.V. Kozelov (2013) Substorm-associated explosive magnetic field stretching near the earthward edge of the plasma sheet. J. Geophys. Res., 118, 3323— 3335, doi:10.1002/jgra.50344. Kozelova Т., М. I. Pudovkin, and L. L. Lazutin (1989) Characteristics of the growth of stimulated and spontaneous magnetic substorm according to satellite and ground-based data. Geomagnetism and Aeronomy, V. 29, N 6, p. 800-804. Keiling A., H. Reme, I. Dandouras et al. (2004) New properties of energy-dispersed ions in the plasma sheet boundary layer observed by Cluster. J. Geophys. Res. 109, A05215, doi:10.1029/ 2003JA010277. Lazutin L. L. et al. (1998) Observations of substorm fine structure, Ann. Geophysicae. 16, 775-786. Lyons L. R. (1995) A new theory for magnetospheric aubstorm, J. Geophys. Res., 100, A10, 19,069—19,081. Mishin V. et al. (1992) Substorm scenario with two active phases: a study of CDAW-9C events. Proc. Substorm-1, Kiruna, Sweden ESA SP-335, 383-389. Sergeev, V. A., et al. (2000), Plasma sheet ion injections into the auroral bulge: Correlative study of spacecraft and ground observations, J. Geophys. Res., 105, 18,465-18,481. Samson, J. C., and K.L. Yeung (1986) Some generalizations on the method of superposed epoch analysis, Planet. Space Sci., 34, p. 1133. 25