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.

“Physics of Auroral Phenomena", Proc. XXXIIIAnnual Seminar, Apatity, pp. 21 - 24, 2011 ©Kola Science Centre, Russian Academy of Science, 2011 Polar Geophysical Institute NONLINEAR CONNECTION OF RING CURRENT AND AURORAL ELECTROJETS ACTIVITY WITH SOLAR WIND AND INTERPLANETARY MAGNETIC FIELD PARAMETERS O.M. Barkhatova1, S.E. Revunov2 1. Nizhniy Novgorod State Universityfo r Architecture and Civil Engineering, Nizhniy Novgorod, Russia 2. Nizhniy Novgorod State Pedagogical University, Nizhniy Novgorod, Russia Abstract. The influence of Solar wind and Interplanetary Magnetic Field (IMF) concrete parameters on ring current and auroral electrojets current systems during geomagnetic storms main phases is investigated. The manifestation degree of these heliogeophysical parameters in considered current systems was determined with use of standard linear correlations and nonlinear connections established on the base of artificial neural networks. The analysis o f linear correlations and neural network experiments show that Solar wind velocity, Bz component IMF and less Solar wind concentration have an impact on auroral electrojets development during the geomagnetic storm main phase. The influence of By component expressed poorly. It is founded that Solar wind density has the greater influence on eastward electrojet while Solar wind velocity has the greater influence on westward electrojet. The IMF Bz component is the strongest agent determining intensity of ring current symmetric and asymmetric parts. It means that Bz component dynamics directly drive a ring current behaviour. The Solar wind density and velocity have not an evident influence on a ring current. Perhaps it’s due to ring current contents up to 80 % ionospheric ions during magnetic storm main phase. 1. Introduction The geomagnetic storm main phase is an interval of the greatest increase in ring current activity which is frequently accompanied by auroral electrojets intensification. The question on connection of these current systems is still not clear, but it is no doubts that their activation has the general solar source. The establishment of Solar wind (PSW) and Interplanetary Magnetic Field (IMF) parameters which have the greatest influence on magnetospheric and ionospheric current systems dynamics is one of the key problems. It is well known that Bz component IMF is one of the key parameters determining a ring current development during magnetic storms [Tsurutani et al., 1992; Gonzalez et al., 1994]. The statistical research for 130 geomagnetic storms carried out in work [Lyatsky and Tan, 2003] shows that during storm development peaks in absolute values not only Bz component but also By component IMF are observed. Besides within several hours before depression of Dst index which show a ring current development degree, growth of Solar wind velocity and density is marked. The research of auroral response on variations of Solar wind and Interplanetary Magnetic Field parameters shows that growth of Solar wind dynamic pressure frequently leads to typical substorms occurrence [Kokubun et al., 1977; Zhou and Tsurutani, 2001]. Development of a typical substorm is accompanied by generation or intensification a two-vortical current system such as DP2 [Sergeev et al., 1996; Nightingales, etc., 2006]. 2. Used data For the current research 30 isolated geomagnetic storms of various intensity for 2001-2003 have been selected. The influence of PSW and IMF on ring current and auroral electrojets current systems is carried out during the main phases o f these storms. Indices SYM, ASY defined intensity o f ring current symmetric and asymmetric parts and AU, AL indices - intensity of eastward and westward polar electrojets development. As primary geoeffective PSW and IMF we considered: Solar wind velocity V, its density N or their combination, IMF components By and Bz. These data have been taken from satellite ACE with a two-hour advancing of a considered geomagnetic storm main phase. This advancing time include the time necessary to carry PSW to magnetospheric boundary and time to inside-magnetosphere processes development. Therefore the search of linear correlations has been made with shift of values AU, AL, SYM, ASY indices relatively PSW and IMF. Thus, all 16 pairs of indices have been considered: N-AU, N-AL, V-AU, V-AL, By-AU, By-AL, Bz-AU, Bz-AL, N- SYM, N-ASY, V-SYM, V-ASY, By-SYM, By-ASY, Bz-SYM, Bz-ASY. It allows to investigate the influence of each interplanetary environment parameter on the concrete current system development. 3. The search of linear correlations The analysis of the results received by linear correlations calculation for the specified pairs of indices allows to establish the common features of PSW and IMF influence on magnetospheric and ionospheric current systems development during geomagnetic storm. The established dependences have been assigned as a basis of nonlinear connections search between corresponding indices. 21