An Improvement of the IGMK Model to Derive Total and Diffuse Solar Radiation at the Surface from Satellite Data

Abstract For a better understanding, of climate, as well as all kinds of solar power applications it is necessary to know about incoming solar radiation at the surface (global radiation) and its partition into disuse and direct components Over the last ten years, several studies have been undertaken to demonstrate the capability of satellite-based methods for analyzing the downward solar radiation at the surface. At the University of Koin the so-called IGMK model was developed by Moser and Raschke to determine global radiation from geostationary satellite data. We now present some improvements of this IGMK model. These improvements include a totally new treatment of cloud transmittance in combination with the clear-sky atmospheric state. In this new algorithm we now explicitly account for multiple reflections between surface and atmospheric layers, which is most important for the diffuse component of global radiation. Thus, one additional major advantage of the new IGMK model is that the diffuse component...