Solar Variability and its Relevance for the Solar-Terrestrial Environment

Our nearest star, the Sun, has through its radiation a direct influence on the Earth and the terrestrial climate. However, the solar irradiance is not constant but changes on the average with a period of 11 years - the solar activity cycle. Some of the phenomena in relation to the changing solar activity are e.g. the dark sunspot, the bright faculae, the high energetic flare events or the solar wind. Large sunspot groups produce a decrease of the solar constant, due to their lower temperature compared to the surrounding solar atmosphere. The solar constant is the amount of solar energy which reaches the Earth outside of its atmosphere per unit time and per unit area. Strong flare events can influence the orbits of satellites, the terrestrial radar contacts or can even cause the failure of electric power lines. These are only a few examples demonstrating the direct influence of solar activity on the terrestrial environment. To detect changes in solar activity and possible influences on the Earth as soon as possible, a continuous monitoring of the Sun from ground-based observatories as well as from space by satellite missions is necessary. With this research project a new program for the synoptic monitoring of the Sun with high time cadence (up to one observation per minute) and with various instruments, including a new photometric solar telescope, will be initiated, obtaining photometric full-disk observations in different wavelengths, magnetograms, and dopplergrams practically simultaneously. Using these observations, the influence of the various activity phenomena on the variations of the solar constant will be studied. This will also lead to improved models for the reconstruction of the solar variability in the past Another key point is the analysis of the conditions and processes which are responsible for flaring activity. This analysis of the conditions and processes which are responsible for flaring activity. This analysis will be based on the new techniques of artificial neural networks and non-linear dynamics. A long-term goal will be the development of a flare forecasting system. All observations obtained will be available to the public via the Internet and will also serve as ground-based support data for space missions. Therefore, this project will be incorporated into an international network devoted to the observation and analysis of solar variabilities.