THE SOLAR ORIGIN OF THE JANUARY 1997 CORONAL MASS EJECTION, MAGNETIC CLOUD AND GEOMAGNETIC STORM

The magnetic cloud and geomagnetic storm on January 10-11, 1997 were a ssociated with a halo-type Coronal Mass Ejection (CME) observed by the SOHO/LASCO coronagraphs near the sun on January 6. We summarize the s olar activity related to this CME and the subsequent storm at Earth. T his solar activity was remarkably weak and unimpressive. If the wide C ME had not been observed, the storm would not have been forecast. Thus this case represents an extreme example of so-called ''problem'' magn etic storms that lack obvious surface signatures of eruptive solar act ivity. It supports the view that CMEs involve the destabilization of l arge-scale coronal structures which may or may not have associated sur face activity, and that CMEs, not the surface activity, are the key ca usal link between solar eruptions and space weather at Earth.