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.

I.V. Despirak et al. January 1—6, 2007. There was a geomagnetic storm January 2—8, 1995, and the”polar“ substorm was observed during its recovery phase. Fig. 2 shows the solar wind parameters for the 1.5 hour interval preceding the moment of the substorm maximal development. The averaged IMF Bz component, the Ey component of the electric field, the temperature T, and the dynamic pressure P of the solar wind are shown. “Polar” substorms are marked by the diamonds, and “high-latitude ones are noted by the crosses. It is evident that the solar wind velocity is the main differentiating factor for these two substorm types. “Polar” substorms are observed at low solar wind velocities (mainly -300—400 km/s), and “high- latitude” substorms are observed at high velocities (> 500 km/s). In addition, “high-latitude” substorms are observed at higher values of the temperature and the pressure than polar substorms. нs N W 4 2 - 0 - - 2 - - 4 - -6 ♦ "Polar" substorms + "H igh-latitude" substorms ♦ ♦ + ~T— I— r 1— T— I— '— I— T— i 1 I -200 -300 -400 -500 -600 -700 -800 Vx, km/s a 1000000 M 800000 € 3 600000 -\ 2 I 400000 I H 200000 + + + , - I — I’ I I I I I I I ^ I -200 -300 -400 -600 -600 -700 -800 Vx, km/s С S s Ы 4 -t 3 - 2 - 1 0 -1 4 -2 I -----1-----!-----1-----1-----|-----Г — J-----.-----|-----!-----1 200 -300 -400 -500 -600 -700 -800 Vx, km/s b e 6 E яe a 4 - 2 - + + + + z a p 1 I I |------ 1 ------- 1 ------ г -200 -300 -400 -500 -600 -700 -800 Vx, km/s d Figure 2. IMF and solar wind parameters: (a) IMF Bz, (b) IMF EY, (c) temperature T, and (d) solar wind dynamic pressure P averaged over 1.5 hours before the onsets of polar (diamonds) and high latitude (crosses) substorms. The standard deviation was calculated for all considered parameters (Vx, Bz, EY, T, P) before the onsets of these two substorm types. It is shown that disturbances (the standard deviations) of the parameters are higher before the occurrence of “high latitude” substorms than “polar” substorms. (The picture is not presented here). Conclusions We have carried out a comparative analysis of the conditions for the occurrence o f substorms at high geomagnetic latitudes on the basis of the data of the IMAGE geomagnetic stations. It has been shown that substorms for which disturbances are identified only at geomagnetic latitudes higher -70° are observed at a low solar wind velocity, after the passage of a recurrent high speed stream, during the late recovery phase of a geomagnetic storm. Substorms during which disturbances move from the auroral (<70°) to the polar (>70°) latitudes are in contrast observed at a high solar wind velocity and increased values of solar wind temperature and pressure while a recurrent high speed stream passes by the Earth. In addition, the variability o f solar wind parameters for the “high latitude” substorms is stronger than for “polar” substorms. Acknowledgements. The paper was supported by Program No 22 of the Presidium of the Russian Academy of Sciences (RAS) “Fundamental problems of the Study and Exploration of the Solar system” and with a partial 12