Images of total O VI 1032 line intensity and profile width in the
north polar coronal hole observed on April 6-9, 1996.  In the intensity
plot on the left, brighter regions are white and dimmer regions are
dark.  In the line-width plot on the right, black/blue regions
correspond to narrow profiles and yellow/red regions correspond to
wider profiles.  Note the general anti-correlation between intensity
and line width.  This indicates either a lower ion temperature or a
smaller level of transverse wave broadening in dense polar plumes,
compared to the dimmer interplume regions.

(Giordano et al. 1997, ESA SP-404, p. 413; Giordano et al. 2000,
Astrophys. J., 531, L79)