ИСТИНА

Crossings of the magnetopause near the subsolar point are analyzed using data of THEMIS mission. Variations of the magnetic field near magnetopause measured by one of THEMIS satellites are compared with simultaneous measurements in the solar wind by another THEMIS satellite. 30 and 90 s averaging of magnetic field in the magnetosheath is produced. The results of averaging are compared with the results of measurement just after the magnetopause crossing. It is shown, that Bx-component of the magnetic field near magnetopause is near to zero, which supports the possibility to consider the magnetopause as the tangentional discontinuity. Comparatively good correlation of By-component in the solar wind and near the magnetopause is observed. The correlation of Bz-component near the magnetopause and IMF is practically absent. It is shown, that in many cases the sign of the Bz-component of magnetic field near the subsolar point does not coincide with the sign of IMF Bz-component. The results of the analysis create definite difficulties to simplified theories of magnetic reconnection of solar wind magnetic field at the magnetopause.