Two examples of observation of nearly simultaneous motion of the magnetopause and Earth's bow shock on the Interball-1 and Geotail satellites

We consider nearly simultaneous crossings of the magnetopause and the Earth 's bow shock, recorded on October 11, 1996, onboard two satellites in the r egions separated by 30R(E) (Interball-1 in the magnetotail and Geotail in t he subsolar region). The analysis of measurements and their comparison with model calculations of the mentioned boundaries have shown that, as a resul t of the arrival to the Earth of the front of a solar wind disturbance, nea rly simultaneous motion of the whole magnetosphere boundary took place in g ood agreement with variations of interplanetary medium parameters. In this case, the measured time delay between the boundary crossings on the two sat ellites can be explained only by the large (up to 38 degrees) inclination a ngle of the disturbance front to the Earth-Sun line. The same solar wind di sturbance caused the formation, near the subsolar bow shock, of a series of regions filled with hot plasma flowing across the Sun-Earth direction, hot flow anomalies (HFA). This phenomenon is, apparently, responsible for the unusual behavior of the boundaries, in which the Earth's bow shock on the d ayside moved away from the Earth, whereas the magnetopause on the tail Bank , on the contrary, approached it.