Position and motion of the magnetopause during arrival of a magnetic cloud to the earth on January 10 and 11, 1997

This work is aimed at an analysis of magnetopause locations during the arrival of a magnetic cloud at the Earth on January 10-11, 1997; a comparison with the magnetopause models; and estimations of the velocity of the magnetosphere boundary motion. The results of magnetic field and plasma density measurements by the INTERBALL-1 satellite and its MAGION-4 subsatellite are used as input data. Interplanetary medium properties (the solar wind plasma dynamic pressure and interplanetary magnetic field direction) were determined using the data from the WIND satellite, which was then located at a distance of about 100 R_E upstream in the solar wind flow. Data on crossing the magnetopause from other satellites were also used: GEOTAIL was located near the subsolar point on January 10, and on January 11, at the flank of the magnetosphere near its boundary; LANL-084 in geosynchronous orbit passed the magnetopause several times on January 11, 1997. Empirical models by Roelof and Sibeck, Kuznetsov and Suvorova, and Shue were used to describe the magnetopause. A comparative analysis of simultaneous measurements of plasma flows by the INTERBALL-1, GEOTAIL, and WIND spacecraft allowed us to estimate the front inclination of the interplanetary shock wave propagating ahead of the magnetic cloud front and the velocity of a disturbance motion from the subsolar magnetosphere region into the magnetotail. Estimates of the magnetopause motion velocity are found on the basis of a correlation of ion flux measurements by INTERBALL-1 and MAGION-4 separated by a fairly small distance.