High-latitude Pc4 geomagnetic pulsations generated by the interplanetary magnetic cloud approaching the earth on January 10, 1997

Based on observational data collected at high latitudes (Antarctic observat ory Dumont d'Urville and Scandinavian Magnetometer Network IMAGE), it has b een demonstrated that the turbulent region ahead of the interplanetary magn etic cloud that approached the Earth on January 10, 1997, resulted in the g eneration of Pc4 geomagnetic pulsations with the maximum at 8-12 MHz. Their maximum amplitude was observed near the equatorial boundary of the polar c ap. The enhancement of the high-latitude Pc4 pulsations was accompanied by the development of the westward electrojet and intensification of the auror as. A cluster analysis of the dependence of the Pc4 amplitude on the situat ion in the IMF revealed a close relationship between these geomagnetic puls ations to the IMF B-y component and the solar wind velocity. The simultaneo us enhancement of the high-latitude Pc4 in the region of the auroral electr ojet and the development of auroras at large values of the IMF B (similar t o8-14 nT) and a cone angle of > 60 degrees led us to the suggestion that th e geomagnetic pulsations observed do not result from an excitation of extra magnetospheric upstream waves but are produced by a local ionospheric sourc e.