On the Dynamic Character of the Polar Solar Wind

Abstract:

SOHO LASCO C2 and STEREO SECCHI COR 2 coronagraph images, when analyzed using correlation tracking techniques, show a surprising result in polar coronal hole regions ordinarily thought of as “quiet” solar wind. Here what we observe is not the static well-ordered flow and gradual acceleration expected of quiescent regions. Rather, the coronagraph images show outflow in polar coronal holes as intermittent, highly-variable solar wind speed structures. We compare measurements of these structures in different simultaneously-measured coronagraph images, and with coronal brightness. The distribution of structure speeds shows a gradual decrease with speed in the overlap regions of the two coronagraphs. Measurements of the mean speed derived versus height shows the solar wind acceleration with position angle, and are compared with mass flux and other determinations of solar wind outflow over the large polar coronal hole regions. In this presentation we give the most recent work on this ongoing analysis.