Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

Behavior o f the 5577A and 6300Л emissions during substorms connected with recurrent solar wind streams The second studied substorm is observed in 22:16:41 UT, the polar edge of the auroral bulge came in zenith in 22:17:11, after that the station stayed inside the auroral bulge (Figure 2, upper panel). The upper panel of Figure 2 shows the substorm development by chosen images of the red (up) and green (down) lines intensity taken from ASI. The arrow on the upper left image points to the North direction. The bottom panel presents the course o f the green and red line intensities and their ratio during the auroral bulge development, observed in the station zenith. The ratio 1бз<хД5577= 0.033 at the polar edge of the auroral bulge and the average 1бзо(Л5577 = 0.17 inside it. ut . j.n.:oo.< Fig. 2. Development of the second substorm on 3 November 2005 at Andenes by the all-sky imager and course of emissions intensities and their ratio in zenith (bottom panel). 0 22 15 22:19 (upper panel) During the examined substorms on 26 January 2006 at Longyearbyen, associated with RS, Vx — 600 km/s; -650 km/s, Bz ~ -8 nT. These substorms are examples of substorm observation at high latitudes (LAT=78.2°N) during a recurrent stream of the solar wind. The first substorm (not presented in the pictures) is observed from Longyearbyen at 17:17:21 UT, the polar edge of the auroral bulge reached the station zenith at 17:25:41 UT, further the zenith was inside the bulge. At the polar edge of the auroral bulge I 6300 /I 5577 = 0.336 and the average ratio inside it is I 6300 /I 5577 = 0.581. The ratio of the I 6300 /I 5577 values inside the bulge to the one at the polar edge of the auroral bulge is 1.73. The development of the second substorm on 26 January 2006 at Longyearbyen is presented in Figure 3. In the upper panels, images of the 5577 A showing the development of the auroral bulge are presented. The black point indicates the station zenith. The bottom panels show the course o f the 5577 A, 6300 A emissions and their ratio I 6300 /I 5577 during the substorm development. For the emissions intensities and the corresponding ratio, data of the 5577 A intensity in the station zenith and the 6300 A intensity on the same geomagnetic line as the 5577 A one are used. Black arrows point in the graphs to the moments presented in the images in the upper panels.The substorm is seen from the station in 21:02:40 UT. The polar edge of the auroral bulge is observed over zenith in 21:18:10 UT. I 6300 /I 5577 = 0.095 at the polar edge of the auroral bulge and its average value inside the bulge is 0. 232. The ratio of the I 6300 /I 5577 values inside the bulge to the one at the polar edge o f the auroral bulge is 2.45. Discussion and conclusions The emissions intensities ratio I 6300 /I 5577 characterizes the hardness o f the precipitating electrons spectrum (Rees and Luckey, 1974), we used this parameter to make a rough estimate of the electrons energy in the auroral arcs, observed in different parts of the auroral bulge - at the polar edge of the bulge and inside it. During the appearance o f the substorm aurora near zenith, i.e. at the polar edge of the auroral bulge, the green line intensity sharply increased and the emissions intensities ratio I 6300 /I 5577 >n all examined cases reached a minimum, thus testifying for the precipitation of more energetic electrons. Therefore, the precipitation of the most energetic electrons takes place at the polar edge of the auroral bulge. 27