A COMPARISON OF INTERPLANETARY CORONAL MASS EJECTIONS AT ULYSSES WITHYOHKOH SOFT-X-RAY CORONAL EVENTS

Coronal Mass Ejections (CMEs) observed at several AU by the Ulysses sp acecraft are mapped radially back to the Sun and compared with Yohkoh Soft X-ray Telescope (SXT) images of the corona in an effort to identi fy correlated events. Correlations between the observations were diffi cult to make during the ecliptic phase of the Ulysses mission when the satellite footprint was at low heliographic latitudes and the Sun was particularly active e. During its traversal to high southerly latitud es (February 1992 - September 1994), however, the correspondence becam e clearer for two reasons: 1)the radial velocity profiles of the high- latitude CMEs were better preserved since they were less likely to be driving shocks or to have interacted with high-speed streams; and 2) s olar activity decreased, making it easier to discern individual and/or low-intensity events in the SXT images. We describe five Ulysses-obse rved CMEs which correlated with spatially and temporally isolated coro nal X-ray events in the Yohkoh SXT images, concentrating on similariti es and differences between their solar wind and coronal structures. Tw o of the five events appeared to have been initiated concurrently with active region (AR) hares. the other three involved the restructuring of low-intensity, polar crown arcades. Significantly, however, all fiv e events exhibited an ''LDE'' signature, though only the two AR events generated a detectable signal above the GOES integrated background X- ray flux. The characteristics of the interplanetary CMEs were not well correlated with their coronal X-ray signatures: similar-looking coron al events produced very different interplanetary held structures, and different-looking coronal signatures evolved into remarkably similar s tructures at Ulysses. Although Eve suspect that all of the events may have had an initially helical held structure, only three of the events displayed coherent field rotations characteristic of nearly force-fre e flux ropes (two of these were associated with polar crown arcades an d one with an AR flare). It appears that the most important factor in determining the magnetic held evolution of a CME in interplanetary spa ce is its plasma beta, but that it is very difficult to predict the in terplanetary beta based on the post-eruption coronal X-ray signature.