  The chromospheric H-alpha spectral line is a strong line in the spectrum of
the Sun and other stars. In the stellar regime, this spectral line is already
used as a powerful tracer of stellar activity. For the Sun, other tracers (i.e,
CaII K) are typically used to monitor solar activity. We used observations of
full-disk H-alpha filtergrams of the Chromospheric Telescope (ChroTel) to
extract the imaging H-alpha excess and deficit, which are related to bright
features (plage regions) and dark absorption features (filaments and sunspots),
respectively. The aim of this study is to introduce the imaging H-alpha excess
and deficit as tracers of solar activity and compare them to other established
indicators: the relative sunspot number, the F10.7cm radio flux, and the MgII
index. The H-alpha excess and deficit follow the behavior of the solar activity
over the course of the cycle, whereby the peak of the H-alpha deficit is
shortly after the solar maximum. The H-alpha excess is closely correlated to
the chromospheric MgII index. The highest correlation of the H-alpha deficit is
found with the F10.7cm radio flux. The H-alpha deficit reflects the cyclic
behavior of polar crown filaments and their disappearance shortly before the
solar maximum. We investigated the mean intensity distribution for H-alpha
excess regions for solar minimum and maximum, whereby the shape of the
distributions is very similar, but with different amplitudes. Furthermore, we
investigate whether the area coverage fraction or the changing H-alpha excess
in the active regions dominates temporal variability in solar H-alpha
observations. The area coverage fraction and the H-alpha excess are strongly
correlated, whereas the weak correlation between the area coverage fraction and
mean intensity leaves us pessimistic that the degeneracy between these two
quantities can be broken for the modeling of unresolved stellar surfaces.
