Observations of almost simultaneous crossings of two boundaries (bow shock and magnetopause) using Interball 1 and Geotail data

The problem of the motion of boundaries (bow shock and magnetopause) was studied using several nearly simultaneous crossings of the bow shocks and/or magnetopause identified by plasma and magnetic field measurements onboard Interball 1 and Geotail satellites. One of such observations, on 11 October 1996, when the satellites were at a distance of up to 30 RE from each other, shows two different events: simultaneous bow shock and magnetopause sunward motion as a response to solar wind plasma and IMF disturbances and almost simultaneous bow shock sunward and magnetopause earthward motions. Some causes of such behavior of the boundaries, including the influence of hot flow anomalies of the solar wind, are discussed.