Physics of auroral phenomena : proceedings of the 36th Annual seminar, Apatity, 26 February – 01 March, 2013 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2013. - 215 с. : ил., табл.

I. V. Despiraket al. All auroral disturbances observed by Polar during RS, MC, Sheaths and CIRs for the periods December 1996 and 1997-1998 were studied. 6 events were selected when Geotail was in the plasma sheet during the auroral bulge formation connected to Sheath, 3 events - to CIR, 3 events- to MC and 7 events - to RS. Below we present one example connected to solar wind magnetic cloud (MC). Results Auroral disturbances during MC event on 13 November 1998 A magnetic cloud (MC) arrived at ~ 05:00 UT on 13 November and passed away at ~ 07 UT on 14 November 1998 (as deduced from Wind data). The Sheath was registered from ~01 UT to -0 5 UT. A substorm was observed at 21:47 during the MC passage. The blue line on Fig. (la ) delimits the intervals o f Sheath and MC, the interval o f MC is red-crosshatched. In front of the magnetic cloud there is a region o f interaction with slower streams (Sheath). This is a region with magnetic field and plasma compression. Vertical blue lines and blue crosshatched regions show the times o f Sheath (Fig. 1a) The black solid line shows the onset time of the substorm registered by the Polar satellite. On the top panel o f Fig. (lb), the auroral bulge development from 21:47 to 22:11 UT according to Polar UVI data is shown. The onset latitude L0 of the bulge was 53.3° CGLAT; the maximum latitude L™- 72.6° CGLAT; the latitudinal size Llat -16.7° CGLAT, the longitudinal size Liong~ 162° CGLAT, the ratio between the longitudinal and the latitudinal sizes Liat/Llong was equal to ~ 9.7. Keograms on the bottom panel o f Fig. (lb ) demonstrate the clear poleward expansion of the bulge. Geotail data for the period 20 - 24 UT on 13 November 1998 are presented in Fig. (lc). The satellite started registering fast tailward plasma flows about 21:59 UT, a flow reversal took place at ~ 22:00 UT and a maximum of earthward flow is observed at 22:07 UT. The flow reversal is associated with a decrease o f the total (magnetic plus plasma) pressure, which followed a period of a pressure increase. Auroral disturbances development by POLAR UVI Solar wind and IMF uw.ee г<-<м** «*н*иг »**» w ггльи at гглмаиг GEOTAIL data Fig. 1. Auroral disturbances during MC event -13 November 1998. (a) From top to bottom: total magnetic field B, three magnetic field components, SW flow velocity, density, dynamic pressure; (b) Top: auroral bulge development from onset to maximal phase. Bottom: keograms in the LBHL emission (black line) and LBHS emission (blue line) at the meridian o f Geotail footprint. Vertical lines indicate the times o f plasma flows in magnetotail by Geotail data; (c) From top to bottom: temperature, density, MF component Bx, total pressure, plasma (3, GSM X component o f the velocity. 10