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.

M.S. Pulinets et al. was considered as the angle produced in the vertical plane from the vector addition of the By and B2 components of the IMF (in GSM coordinates). Mean value and dispersion were calculated for each variable. The magnetic field parameters near the magnetopause were averaged over periods of 30 and 90 seconds after crossing the magnetopause (what was fixed simultaneously by changes in the parameters of plasma and magnetic field). The first point of the magnetosheath was taken as the last data point before or the first after the significant change in the parameter value. Values of the magnetic field, averaged over 3 s, i.e. field directly close to magnetopause was also analyzed. The solar wind parameters were averaged over a maximum period o f 90 s taking into account the time shift of solar wind propagation from the spacecraft performing measurements in the solar wind to the magnetopause. The shift was calculated as the time of the solar wind passing the difference between x- coordinates of the spacecrafts in the approximation of the radial propagation of the solar wind. Solar wind velocity was determined from the data of THEMIS probe located in the solar wind. It was considered in the magnetosheath as reduced by about two times as a result of thermalization. The magnetosheath thickness was supposed to be approximately ~ 2 RE. For each case the time shift was calculated individually for the specific spacecraft coordinates. Since the errors of the order of ten seconds are possible when calculating the time shift, the averaging of values in the solar wind was made for a maximum period of 90 seconds to minimize them. 50 events were analyzed, 25 of them with nortward magnetic field in solar wind and 25 with southward. Figures 1 - 5 show the dependences of the magnetic field parameters near the magnetopause on the solar wind parameters. A set of three curves is given for each parameter. The first distribution is plotted for the instantaneous values (three second averaging) after crossing the magnetopause, the second - for the averaged over a 30-s interval after crossing, the third - for the averaged over a 90-s interval. Averaging in the solar wind is realized for a maximum period of 90 s (taking into account the time shift of the solar wind propagation to the magnetopause) in order to minimize errors due to deviation of the estimated solar wind delay from the real delay. For each point, an error calculated as the standard deviation over the averaging periods is also shown. In Figures for the instantaneous values the errors are shown only for the averaging in the solar wind. a) b) c) Fig. 1 The dependence of the magnetic field magnitude for the considered set of events a) over 3 seconds after crossing the magnetopause, b) averaged over a period of 30 seconds from the moment of crossing c) averaged over a period of 90 seconds - on the magnitude in the solar wind. The values of the magnetic field magnitude (see Figure 1) at the magnetopause noticeably trend to increase when increasing magnitude in the solar winds. The form of the distribution remains essentially unchanged when the period of averaging is increased. a) b) c) Fig. 2 The dependence of the x-component of the magnetic field for the considered set o f events a) over 3 seconds after crossing the magnetopause, b) averaged over a period of 30 seconds from the moment of crossing c) averaged over a period of 90 seconds - on the Bx in the solar wind. In accordance with Figure 2 the x-component of the magnetic field at the magnetopause does not depend on the corresponding value in the solar wind and fluctuates around zero, which is in accordance with the assumption of magnetopause as a tangential discontinuity. As well as for the field magnitude, the increase in averaging interval does not change the form of the distribution of points on the graph. 46