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.

SUBSTORM OBSERVATIONS IN APATITY DURING DIFFERENT SOLAR WIND CONDITIONS V. Guineva1,1. Despirak2, B. Kozelov2 1 Space Research and Technology Institute - Bulgarian Academy o f Sciences, Stara Zagora, Bulgaria, e-mail: v _guineva@yahoo.com 2Polar Geophysical Institute, Apatity, Russia Abstract. All-sky camera data obtained at Apatity (Kola Peninsula) during 2012/2013 winter season have been used to study the variation of substorm development in different conditions of interplanetary medium. Solar wind and interplanetary magnetic field parameters were taken from CDAWeb (httpJ/cdaweb.gsfc. nasa.gov/cdaweb/ istp_public/). Using WIND satellite data for the examined periods, the different solar wind streams were revealed: recurrent streams from coronal magnetic holes (RS) and magnetic clouds (MC) connected with non-stationary processes at the Sun. It is known that these solar wind structures are the sources of geomagnetic storms. Furthermore, the storms originating from these sources differ in intensity, recovery phase duration, etc. We investigated substorm development during storms and during quiet conditions. Substorm onset time and further development were verified by ground-based data of IMAGE magnetometers network and by data of all-sky cameras at Apatity. The particularities in behaviour of substorms observed during storms and during quiet conditions are discussed. Introduction Substorms are a specific phenomenon, related to a number of processes in the magnetosphere and ionosphere, generalized by Akasofu [1]. It was established that the substorm development goes on in the following way: the substorm expansion phase begins with the flash of one arc, usually the most equatorial one of the already existing discrete auroral arcs. Then there is formed an auroral bulge - an area occupied by bright, short-lived arcs. It is expanding in all directions, mainly poleward, to the West and to the East [2, 3]. At the time of maximal stage of substorm development the auroral bulge reaches its greatest width and occupies a maximum area. Further, during the recovery phase, the auroral bulge begins to shrink, its polar edge moves to the equator and, the South one - to the pole, the bright discrete arcs degenerate into irregular strips and fade [4, 5]. It is known, that the substorm generation and development depends on the conditions in the solar wind [e.g., 6, 7, 8]. The solar wind conditions include the solar wind parameters values, as well as the presence o f different solar wind streams and their structure [9].The solar wind streams can be recurrent streams (RS) originating from coronal magnetic holes, characterized by a 27-day recurrence, which predominate during solar minimum [10], and magnetic clouds (MC) originating from coronal mass ejections (CME) giving rise to sporadic flows, generated more often during a solar maximum [11, 12]. These solar wind structures are usually the source of geomagnetic storms that differ by their main characteristics depending on the generating structure. Therefore the substorms arising during different solar wind flows or under quiet conditions differ by substorm onset location latitude, substorm polar edge latitude, auroral bulge extent etc. Apatity is settled at auroral latitudes. Its geographic coordinates are: 67.58°N, 33.31°E, and the corrected geomagnetic ones - 63.86°N, 112.9°E. This location is expedient to examine the variety of substorms. The goal of this work is to study substorm development as seen from Apatity under different interplanetary and geomagnetic conditions. Instrumentation and data used All-sky camera data observed at Apatity during the 2012/2013 winter season have been used. The all-sky camera has being installed in Apatity since 2008 as a part of observational system MAIN (Multiscale Aurora Imaging Network). It comprises 5 auroral cameras with different fields of view providing simultaneous observations from spatially separated points. The cameras characteristics, their mutual situation and the measurement process are described in detail by Kozelov et al. [13, 14]. Solar wind and interplanetary magnetic field parameters were taken from CDAWeb (http://sdaweb.gsfc.nasa.gov/cdaweb/istp_public/) . WIND satellite data revealed different solar wind streams- recurrent streams from coronal magnetic holes (RS) and magnetic clouds (MC) connected with non-stationary processes at the Sun or quiet conditions for the examined periods. Substorm onset time and further development were verified by ground-based data of IMAGE magnetometers network (using meridional chains), Lovozero and Loparskaya magnetometers and by data of Apatity all-sky camera The measurements during 2012/2013 season were examined together with the interplanetary conditions during the measuring periods. The recurrent streams and magnetic clouds were detected. The substorms developed over 14 “Physics o f Auroral Phenomena", Proc. XXXVII Annual Seminar, Apatity, pp. 14-17, 20 1 4 © Kola Science Centre, Russian Academy of Science, 2014 Polar Geophysical Institute