SOLARNET Conference: The Many Scales of the Magnetic Sun

The total and spectral solar irradiance, TSI and SSI, respectively, vary on many timescales from sub-daily variations to annual, decadal, centennial timescales. The variations of the SSI are also wavelength dependent, with larger relative variations in the EUV/UV and smaller variations in the visible and IR. These irradiance variations allow us to understand, on the one hand, the physics of the Sun as a star and, on the other hand, the key energy source for the Earth's climate system. In this talk I will review the available irradiance measurements, composite datasets, models and how the underlying physics, which drives the irradiance variations, is implemented.