  We investigate the magnetic characteristics of a persistent coronal hole (CH)
extracted from EUV imagery using HMI filtergrams over the timerange February
2012-October 2012. The magnetic field, its distribution as well as the magnetic
fine structure in form of flux tubes (FT) are analyzed in different
evolutionary states of the CH. We find a strong linear correlation between the
magnetic properties (e.g. signed/unsigned magnetic field strength) and area of
the CH. As such, the evolutionary pattern in the magnetic field clearly follows
the three-phase evolution (growing, maximum and decaying phase) as found from
EUV data (Part I). This evolutionary process is most likely driven by strong
FTs with a mean magnetic field strength exceeding 50 G. During the maximum
phase they entail up to 72% of the total signed magnetic flux of the CH, but
only cover up to 3.9% of the total CH area, whereas during the growing and
decaying phase, strong FTs entail 54-60% of the signed magnetic flux and cover
around 1-2% of the CHs total area. We conclude that small scale-structures of
strong unipolar magnetic field are the fundamental building blocks of a CH and
govern its evolution.
