Solar energy mapping by using cloud images received from GMS

Solar energy maps that indicate the wide-ranging spatial distribution of solar irradiation are required by the researchers of the solar power systems. However, the irradiation measurement networks at ground level are not enough to obtain reliable information of the solar energy distribution in the world. On the other hand, geostationary meteorological satellites (GMS) have provided the images of cloud fields over the whole surface of the Earth. The main cause of an irregular change in the irradiation at the ground level is effect of the clouds; therefore, methods for estimating the irradiation by using the GMS images may be very useful. The solar irradiation for 14 sites in Japan was estimated by a semi-physical model developed by the authors. The RMS errors, averaged over 14 stations, were 0.0804 kWh/m/sup 2/ for hourly estimates, 0.534 kWh/m/sup 2/ for daily estimates and 7.14 kWh/m/sup 2/ for monthly estimates. There were little regional differences of estimate accuracy. An example of solar energy maps for Eastern Asia in 1992 is presented.