Physics of auroral phenomena : proceedings of the 38th annual seminar, Apatity, 2-6 march, 2015 / [ed. board: A. G. Yahnin, N. V. Semenova]. - Апатиты : Издательство Кольского научного центра РАН, 2015. - 189 с. : ил., табл.

V. V. Vovchenko and E.E.Antonova Dst Figure 4. Dependence of the number of observed events on Dst Figure 5. Dependence of the number of selected events on AE 3. Results o f modeling o f the event 06 June 1985 Trying to analyze the role of the diamagnetism of plasma for the creation of magnetic hole/hump events we produce the modeling of the magnetic field distortion by the observed plasma pressure distribution. The event 06 June 1985 was selected as the results of plasma observations for this event were available and comparatively good. Fig. 6 shows such results. Black and red lines on the upper part of the figure correspond to the observations of the module of the magnetic field В and Bz component of the magnetic field. Coincidence of В and Bz means the satellite position at the equatorial plane. Lower parts are the spectrograms of H* and 0 +ions obtained using CHEM device. Clear pressure hump is observed for the analyzed event. Calculating the distortion of the magnetic field by the observed pressure hump we restore the undisturbed magnetic field distribution suggesting that it is produced by magnetospheric current systems excluding current system connected with pressure hump. We suggest the validity of the condition of magnetostatic equilibrium as the analyzed effect is observed during time interval which is much larger than the sound and Alfven travel times in the magnetosphere. We used the algorithm developed by Vovchenko and Antonova [2010, 2012] for calculation of the nonlinear magnetic field distortion. Fig. 7 shows the results of calculations (red line) and their comparison with the results of observations (black line). Figure 6. Results of the observations of the magnetic field variation, plasma pressure distribution and H+ and 0+ particle fluxes for the event 06 June 1985 4. Conclusions and discussions Hole/humps of the magnetic field in the magnetosphere of the Earth are clearly selected. Data of AMPTE/CCE observations at geocentric distances <8.8Re very near to the equatorial plane demonstrate the appearance of pressure holes in all MLT sectors. The probability to observe pressure holes does not depend on AE and Dst indexes of geomagnetic activity. Formation of observed pressure holes and humps can be connected with local increases of plasma pressure (due to diamagnetic effect). Such formation does not requires tail current distortion of the geomagnetic field and probably connected with ring current effect. R. R e Figure 7. Comparison the results of modeling (red line) with the results of observations (black line) 46