THE OUTER RADIATION BELT DURING THE 10 JANUARY, 1997 CME EVENT

On 10 January 1997 a magnetic cloud of a coronal mass ejection impinge d upon the earth magnetosphere and caused considerable variations of t he relativistic electron population in the earth's outer radiation bel t in the following days. Data obtained with radiation detectors on boa rd a pair of satellites, STRV-1a and STRV-1b in a nearly equatorial ge ostationary transfer orbit show that the electron Aux variations durin g the days following the arrival of the magnetic cloud can be characte rized by four phases during which the fluxes alternatingly decreased a nd increased. The close relation between flux and Dst variations sugge st the magnetic field variations in the inner magnetosphere to play an important role. However, the observed injection of electrons into the trapping region in the morning of 10 January seems to be crucial for the large electron flux enhancement during the afternoon of 10 January .