Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

I. V. Despirak et al. reversal by a spacecraft in the plasma sheet is a substorm signature - it indicates passage of the reconnection site around the spacecraft in the NENL model (e.g. Yahnin et al., 2006a) as shown in Fig. 2, or passage of the current disruption region in the Current Disruption model (e.g. Lui et al., 2008]). XO»m, R, Xe*m, R, Fig. 2. Schematic view of the situation when a satellite in the magnetotail observes a reversal of fast fowls. The region where tailward and earthward flows (shown by arrows) are generated is associated with the X-line. (Figure taken from Yahnin et al., 2006a) During substorm growth phase, as a result of reconnection at the magnetopause magnetic flux is stored in the magnetotail lobes, and in the course of an auroral disturbances this flux is ‘unloaded’ down to the ionosphere. So the total pressure increase followed by a decrease observed during the substorm-reiated fast flows is one of the signatures of substorm development in the magnetotail. Data used The auroral disturbances are studied by Polar UVI data in the LBHL band (1600-1800A); Geotail plasma measurements by LEP instrument, and magnetic field measurements by MGF instrument; the solar wind and interplanetary magnetic field parameters measured by Wind spacecraft were taken from OMNI database. All auroral disturbances observed by Polar during Sheaths and CIRs for the periods 1997-1998; 2000; October 2001 and December 1996 were studied, 8 events when Geotail was in the plasma sheet during the auroral bulge formation connected to Sheath and CIR impact were selected. We present two of them. Results 1) Auroral disturbances during CIR - 29 March 1997 A recurrent stream reached the Earth at about 16 UT on 29 March and passed away at about 04 UT on 31 March 1997 (as deduced from Wind data). The CIR was registered from about 06 UT to 16 UT. Substorm was observed at 14:37 UT. / 'V , . • I v*4, v«*vv-. i ж (а) Solar wind and IMF From top to bottom: total magnetic field B, three magnetic field components, SW flow velocity and Vx, density, thermal pressure, magnetic pressure, dynamic pressure ll:M U.I j л А - -1 J 1 J J *i A i / J у I » U40 >-----— p v > L . T 1 1 1 1 I' f 1 1 > 1* (b) Auroral disturbances development by POLAR UVI Top: auroral bulge development from onset to maximal phase. The blue curves delimit the bulge region Bottom: keograms in the LBHL emission (black line) and LBHS emission (blue line) at the meridian of Geotail footprint. Vertical lines indicate the times of of plasma flows in magnetotail by Geotail data Fig. 3 Auroral disturbances during CIR - 29 March 1997 (c) GEOTAIL data From top to bottom: temperature; density, MF component Bx, total pressure, plasma P, GSM X component of the plasma velocity 18