Irradiance Reconstructions - Evolution of Sources

Natalie Krivova [], Max-Planck-Institut fuer Sonnensystemforschung, Katlenburg-Lindau, Germany.

Measurements of solar irradiance having sufficient precision to reveal itsvariability are available for less than 30 years. This variability is ofobvious interest for Sun-climate studies. The length of the record is,however, to short to allow quantitative estimates of solar influence on theEarth's climate, necessitating a reconstruction of the irradiance change forearlier times. A successful reconstruction is only possible if goodunderstanding of the mechanisms and the sources of the variations is gained. Recent models attributing variations in solar total and spectral irradianceto the evolution of the Sun's surface magnetic features (sunspots, faculaeand the network) reproduce the directly observed variations in great detail. These models and possible lines of their further improvements are discussed. Also considered is the relative contribution of different surface features to the total irradiance variations.