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.

Auroralprecipitation dynamics during the magnetic cloud passing dynamics of auroral precipitation in auroral oval (AOP - the first panel) and precipitation in DAZ (the second panel) are shown. Along the vertical axis at these panels the corrected geomagnetic latitude (CGL) are indicated. The boundaries were calculated from the АРМ. To determine the boundary locations as a function of the elevation angles, the altitude of aurora was adopted to be 120 km for green aurora and 250 km for red aurora. MSP scanned auroral luminosity from the southern to the northern horizon in the ranges 58°- 71° CGL at LOZ and 62°-87° CGL at BAB. December 11, 2004: Here we have optical data from MSP at LOZ only. As seen from Fig. 1 the magnetic storm began at about 1840 UT after southward turn of IMF Bz and the sharp magnetic bay in the AL index. According АРМ from 1400 UT to 1700 UT (Fig. 2a) the LOZ observatory located equatorward DAZ and MSP registered auroral luminosity near northern horizon. The equatorward displacement o f the aurora occurred between 1700 UT and 2200 UT, the aurora shifted to equator up to about 60° CGL. The equatorward shift is associated with southward turn of IMF Bz and storm activity. During this time the SYM/H and the AL indices were minimum (Dst~-50 nT, AL~ -800 nT). From 1700 to 2400 UT the LOZ observatory is situated in the AOP or in the DAZ regions in the pre-midnight, midnight and post-midnight MLTs (Fig. 2a). In ( Vorobjev and Yagodkina, 2005) it was shown that when the Dst index changes from positive to negative, the equatorward boundaries of precipitation shift toward lower latitudes. Auroral luminosity which located poleward DAZ precipitation is situated in region of AOP. The model boundary of auroral precipitation rather well describes the location of auroral luminosity at LOZ. December 12, 2004. After 0000 UT one can see the series of substorms marked by the vertical dashed lines in Fig. 1. The AL indices variations demonstrate the development of magnetic substorms. We examined the auroral dynamic during the 4, 5 and 6 substorms. The substorm 7 was developing under northern turning of IMF Bz. Substorms under study took place in pre- noon, noon and past-noon MLTs. During quiet conditions, before growth phase, the BAB observatory was situated in the AOP region, LOZ was situated in DAZ. During the first substorm marked number 4 the aurora at BAB and LOZ shifted to south horizon. The model boundaries of AOP (at BAB) and DAZ (at LOZ) indicate equatorward expansion to 62° and 58° CGL, respectively. At BAB from about 0000 UT to about 0300 UT the region of AOP is expanded, the equatorward boundary shifted to 62° CGL, the position of poleward boundary locates at about 72°-73° CGL. In Vorobjev et al., 2007b it was shown that all precipitation regions in the dayside sector synchronously shift equatorward not only during the growth phase also but during expansive phase. The largest shift to lower latitudes of the AOP region is observed at a maximum of the expansive phase and during the initial period of the recovery phase. At that time the region of SDP, located poleward o f AOP, becomes very thin and/or disappears. In the near-noon hours the equatorward boundary o f DAZ reaches the lowest latitudes during substorm recovery phase. The magnetic activity increased and reached maximum about -767, 825 and 853 nT, respectively for 4, 5 and 6 substorms. The mean values of the Dst index in the considered periods varied insignificantly and not exceeding ~25 nT. During the every following substorm (5 and 6) the equatorward boundaries of AOP at BAB and DAZ at LOZ drifted to more high latitudes. According to АРМ the equatorward boundaries shifted to pole up to 68° and 64° CGL at BAB and LOZ, respectively. Displacement of poleward boundary at LOZ makes up about 10° CGL, from 63° to 73° CGL. As can see from Figure the discrete aurora at BAB located inside the AOP region. The model boundaries of auroral precipitation allow filling the gaps in the LOZ optical observations and the calculation boundaries rather well describe the location of auroral luminosity. We investigated a distribution of the auroral intensities in green and red lines along the geomagnetic meridian in two time intervals on December 12: from 0623 UT to 0631 UT (pre-noon sector, the initial period of the recovery phase of substorm 5 in Fig. 3) and from 1130 UT to 1200 UT (after -noon sector, the recovery phase of substorm 6 in Fig. 3). Scans of the MSP system for the 557.7 and 630.0 nm emissions are shown in Fig. 4. The vertical dashed line indicates the zenith of BAB. The zenith angles were converted into degrees of corrected geomagnetic latitude (CGL) on the assumption that the altitudes o f 557.7 and 630.0 nm emissions are 150 and 250 km, respectively and are pointed along the horizontal axes. Fig. 4 illustrates the meridional profiles of the 630.0 nm (solid line) and 557.7 nm (dashed line) emissions and ratio of 1 бзоо/ 15 577 - In Fig. 4a the typical distribution for the first interval is shown. In this interval the MSP at BAB registered auroras equatorward of zenith in the region of AOP. As seen from Fig. 4a the red luminosity band was located from about 66° CGL to 75° CGL and according to the model the boundaries which are shown in Fig. 3 filled the AOP region. The discrete auroral forms with intensity about 2-3 kR appeared inside the red band. The ratio I 6300 /I 5577 >1 corresponds to precipitation o f soft electrons with average energy <1 keV (Judge, 1972). Fig. 4b for the second interval was constructed in the same format. The meridional profiles of the emissions are presented in 5 min. For this case the red band is more narrow and located about from 73° to 77° CGL. The green-line discrete forms were located in the middle of the narrow red band in the region of its maximum. The relationship between the emission intensities, 1 бзос/ 15577 ^ 1 > indicates that the discrete forms were 23