Leseprobe
Of all the stars in the Universe, the Sun occupies a vital position for us, as it is the closest star to our planet Earth. It has been long observed and studied. Already by the year 800 B.C. the Chinese had their eyes on the Sun, and have the first written record of an observed sunspot. However, it was not until the time of Galileo Galilei and Christoph Scheiner at the beginning of the 17th century when the first telescopic observations of sunspots began. With these observations also came the notion that the sunspots are actually features on the solar surface and a continuous record of the sunspot number exists since then. Later on in 1843, Schwabe published the first work arguing that the sunspots on the solar surface varied in number with a period of approximately 11 years. Nowadays, the modern space instrumentation has proved the Sun to vary on even shorter time scales down to minutes through phenomena such as flares, coronal mass ejections and other transient events, the 5 minute oscillations (p-modes), or the changing granulation patterns. On the other hand, other proxies like cosmogenic isotope concentrations have implied variations of solar activity on even longer time scales up to centuries and millennia. To describe the evolution of the solar surface magnetic fields we use a surface flux transport model which calculates daily synthetic full-disc magnetograms at the solar surface starting from sunspot positions and areas. These synthetic data are then used as input data in the SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era) model to reconstruct the TSI.
