  Although the Sun's polar magnetic fields are thought to provide important
clues for understanding the 11-year sunspot cycle, including the observed
variations of its amplitude and period, the current database of high-quality
polar-field measurements spans relatively few sunspot cycles. In this paper we
address this deficiency by consolidating Mount Wilson Observatory polar faculae
data from four data reduction campaigns, validating it through a comparison
with facular data counted automatically from MDI intensitygrams, and
calibrating it against polar field measurements taken by the Wilcox Solar
Observatory and average polar field and total polar flux calculated using MDI
line-of-sight magnetograms. Our results show that the consolidated polar
facular measurements are in excellent agreement with both polar field and polar
flux estimates, making them an ideal proxy to study the evolution of the polar
magnetic field. Additionally, we combine this database with sunspot area
measurements to study the role of the polar magnetic flux in the evolution of
the heliospheric magnetic field (HMF). We find that there is a strong
correlation between HMF and polar flux at solar minimum and that, taken
together, polar flux and sunspot area are better at explaining the evolution of
the HMF during the last century than sunspot area alone.
