  Context. The Sun shows an activity cycle that is caused by its varying global
magnetic field. During a solar cycle, sunspots, i.e. extended regions of strong
magnetic fields, occur in activity belts that are slowly migrating from middle
to lower latitudes, finally arriving close to the equator during the cycle
maximum phase. While this have been well known for centuries, much less is
known about the solar cycle evolution of small-scale magnetic fields. Aims. To
address this question, we study magnetic bright points (MBPs) as proxies for
such small-scale, kG solar magnetic fields. This study is based on a
homogeneous data set that covers a period of eight years. Methods. An automated
MBP identification algorithm was applied to the synoptic Hinode/SOT G-band data
over the period November 2006 to August 2014, i.e. covering the decreasing
phase of Cycle 23 and the rise, maximum, and early decrease of Cycle 24. This
data set includes, at the moment of investigation, a total of 4 162 images,
with about 2.9 million single MBP detections. Results. After a careful
preselection and monthly median filtering of the data, the investigation
revealed that the number of MBPs close to the equator is coupled to the global
solar cycle but shifted in time by about 2.5 years. Furthermore, the
instantaneous number of detected MBPs depends on the hemisphere, with one
hemisphere being more prominent, i.e. showing a higher number of MBPs. After
the end of Cycle 23 and at the starting point of Cycle 24, the more active
hemisphere changed from south to north. Conclusions. These findings suggest
that there is indeed a coupling between the activity of MBPs close to the
equator with the global magnetic field. The results also indicate that a
significant fraction of the magnetic flux that is visible as MBPs close to the
equator originates from the sunspot activity belts.
