SPEEDS OF CORONAL MASS EJECTIONS - SMM OBSERVATIONS FROM 1980 AND 1984-1989

The speeds of 936 features in 673 coronal mass ejections have been det ermined from trajectories observed with the Solar Maximum Mission (SMM ) coronagraph in 1980 and 1984-1989. The distribution of observed spee ds has a range (from 5th to 95th percentile) of 35 to 911 km s-1; the average and median speeds are 349 and 285 km s-1. The speed distributi ons of some selected classes of mass ejections are significantly diffe rent. For example, the speeds of 331 ''outer loops'' range from 80 to 1042 km s-1; the average and median speeds for this class of ejections are 445 and 372 km s-1. The speed distributions from each year of SMM observations show significant changes, with the annual average speeds varying from 157 (1984) to 458 km s-1 (1985). These variations are no t simply related to the solar activity cycle; the annual averages from years near the sunspot maxima and minimum are not significantly diffe rent. The widths, latitudes, and speeds of mass ejections determined f rom the SMM observations are only weakly correlated. In particular, ma ss ejection speeds vary only slightly with the heliographic latitudes of the ejection. High-latitude ejections, which occur well poleward of the active latitudes, have speeds similar to active latitude ejection s.