GEOMAGNETIC STORMS CAUSED BY CORONAL MASS EJECTIONS (CMES) - MARCH 1996 THROUGH JUNE 1997

(1) All but two geomagnetic storms with Kp greater than or equal to 6 during the operating period (March 1996 through June 1997) of the Larg e Angle Spectroscopic Coronagraph (LASCO) experiment on the Solar and Heliospheric Observatory (SOHO) spacecraft can be traced to Coronal Ma ss Ejections (CMEs). (2) These geomagnetic storms are not related to h igh speed solar wind streams. (3) The CMEs which cause geomagnetic eff ects, can be classified into two categories: Halo events and toroidal CMEs.. (4) The CMEs are accompanied by Coronal Shock Waves as seen in the Extreme Ultraviolet Imaging Telescope (EIT) Fe XII images. (5) Som e CMEs are related to flares, others are not. (6) In many cases, the t ravel time between the explosion on the Sun and the maximum geomagneti c activity is about 80 hours.