Coordinated SOHO Observations of Polar Plumes

On 7 and 8 March 1996, SOHO instruments engaged in their first joint science operation, a 12-hr observation of polar plumes over the South polar coronal hole. The observing mini-campaign included observations from SOHO, other spacecraft, and ground-based observatories. Contributing SOHO instruments -- in order of altitude, MDI, CDS, SUMER, EIT, UVCS, and LASCO -- made overlapping, simultaneous observations of plume structures from the photosphere out to the LASCO C3 limit of 32 solar radii. MDI provided line-of-sight surface magnetograms with a one-min cadence and 0.6 arcsec resolution; CDS, SUMER, and EIT supplied temperature-sensitive images of the lower corona with varying cadences and resolutions; UVCS measured fluctuations in Ly B intensity across the coronal hole with a one-min cadence at 1.4 R0; and LASCO imaged the entire corona out to 30 R0 in various visible passbands. Plume footpoints in the lower corona are observed by EIT and CDS to vary by a factor of two in EUV brightness with a timescale of tens of minutes, while the structures above are (as as been previously observed) quiescent on at least a ten-hr time scale. We present preliminary results of cross-instrument analysis of the observed plumes, and suggest how this and similar future data sets can be used to constrain quiet-sun wind acceleration and coronal heating models for the coronal hole. This research is supported by the SOI-MDI NASA contract NAG5-3077 at Stanford University. SOHO is project of international cooperation between NASA and ESA.