A Reconstruction of Total Solar Irradiance Since 1700

Abstract. The irradiance of the Sun is reconstructed from 1700 to the present, whereby the contributions of active re-gions and the quiet Sun are modelled separately. A method is proposed which allows the contribution of active-region faculae and sunspots to irradiance changes to be isolated even when only a single proxy of solar activity, such as sunspot relative number, RZ, is available. The resulting reconstruction explicitly takes the non-linear relationship between RZ and irradiance variations into account. Nev-ertheless, due to the decreasing accuracy of the solar proxy data the accuracy of the reconstruction decreases at earlier epochs. The main uncertainty, however, lies in the recon-struction of the quiet-sun irradiance variations