SOLARNET Conference: The Many Scales of the Magnetic Sun

Measurements of solar irradiance and surface magnetic flux sufficiently accurate as to allow assessment of their variability are only available for roughly half a century. Variability on longer time scales is evidenced by proxies. Upon emergence, the magnetic field on the Sun manifests itself as dark (sunspots and pores) and bright (faculae/plage and network) features. The combined effect of their evolution and the solar rotation is the modulation of the solar irradiance. Models relating the variability of the solar irradiance to the evolution of the solar surface magnetic flux account for almost all of the measured variability. Reconstructions of past variability are, however, thwarted by the lack of reliable long-term proxies of solar surface magnetism, in particular those describing bright magnetic features (faculae and network). We will review our recent efforts to improve understanding of the long-term changes in solar magnetic activity and irradiance. These include recovery and analysis of suitable proxies of past solar magnetic activity, examination of the link between sunspot and facular emergence and evolution, as well as modelling efforts to tighten constraints on the long-term solar variability.