Physics of auroral phenomena : proceedings of the 35th Annual seminar, Apatity, 28 Februaru – 02 March, 2012 / [ed. board: A. G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2012. - 187 с. : ил., табл.

E.E. Antonova et al. demonstrate that symmetric part of the transverse current in the ring during magnetic storms create the main contribution in the azimuthally symmetric part of magnetic disturbance at the Earth producing Dst variation. We also discuss the localization of isolated substorm onset. Distribution of pressure in the ring in accordance with THEMIS data Plasma pressure is among the main parameters responsible for the current distribution in plasma systems and plasma stability. Determining plasma pressure within the magnetosphere can also be of a direct practical importance in connection with the problem of predicting space weather [Antonova et al., 2003]. The obtaining of plasma distribution requires measurements of all plasma particles in a wide energy range. That is why comparatively limited information was obtained about plasma pressure distribution. Tsyganenko and Mukai [2003] created a magnetotail plasma pressure model based on the GEOTAIL satellite data at geocentric distances larger than 10 RE. The global distribution of plasma pressure in the night sector using Geotail data was obtained by Wang et al. [2009]. The global pressure distribution in the inner regions of the Earth’s magnetosphere at geocentric distances < 8.87?/r was obtained from the AMPTE/CCE equatorial satellite by DeMichells et al. [1997, 1999], Lui [1992, 2003]. The region of transition from dipole to tailward stretched field lines has been studied relatively poorly. Some pressure profiles in this region were obtained onboard the Interball/Tail probe in [Antonova et al., 2002; Kirpichev et al., 2005]. Data obtained in the process of realization of THEMIS mission (Angeiopoulos [2008], http://themis.ssl.bcrkeley.edW, http://cdaweb.gsfc. nasa,gov/) give the possibility to obtain the global picture of pressure distribution inside the magnetosphere till the dayside magnetopause. First results of the analysis were obtained by Kirpichev and Antonova [2011]. The moments of ion and electron distribution functions were obtained using two different instruments: ESA, which is an electrostatic analyzer of ions in the energy range from 1.6 eV to 25 keV and electrons with energies from 2 eV to 32 keV, and SST, which is a solid state telescope measured ions with energies from 25 keV to 6 MeV and electrons with energies from 25 to -900 keV. The period of satellite rotation about its axis made it possible to calculate the distribution function moments at an interval of 3 s. A local magnetic field with the same time resolution (3 s) was obtained from the FGM magnetometer data. The ion composition was not determined in this experiment; therefore, we subsequently assume that protons make the main contribution, which is a good approximation during magnetically quiet periods [Daglis et al., 1999]. Solar minimum was observed during analyzed period and Dst was mainly larger than -40 nT. The minimal Dst value was about -80 nT. The equatorial plane (XY) was divided into 0.5RE bins in the solar- magnetospheric (SM) coordinate system. The measurements on all five satellites were accumulated and averaged in each bin. When a satellite crossed each bin in the (XY) plane, we averaged the pressure over a 5 min interval in each considered bin. When approaching the Earth (closer than 6 RE), the penetrating radiation results in a distortion in ESA readings [McFadden et al., 2008] which can be the source of uncertainty of pressure at R<6RE. measurements. Fig. la,b shows the averaged picture of the diagonal components of the pressure tensor in a coordinate system attached to a local magnetic field, i.e., the 10 Xsm,R£ -10 b Fig. 1. (a) Distribution of the average value of the pressure perpendicular to the magnetic field (pL) and (b) parallel to the magnetic field (рн) obtained using ESA and SST THEMIS measurements. The thick line shows the magnetopause position in accordance with Shue et al. [1998] model at 10 RE, thin lines show the local magnetic field constant value (in nT) contours obtained in accordance with FGM THEMIS 10