GEOMAGNETIC-FIELD VARIATIONS AT LOW AND HIGH-LATITUDE DURING THE JANUARY 10-11, 1997 MAGNETIC CLOUD

On Jan. 10-11, 1997 a wide magnetic cloud reached the Earth triggering intense geomagnetic activity. Observations performed at low and very high latitude show that the same features appear simultaneously in cor respondence to different changes in the solar wind conditions. In part icular, highly polarized modes are simultaneously observed at the same discrete frequencies after the passage of the high density solar wind region following the cloud. SI's and ULF waves polarization are also examined in a wide latitudinal and longitudinal extent.