Distributed Modeling Of Global Solar Radiation Over Heterogeneous Surfaces In China

China spans a vast territory, with a complex topography and diverse surface conditions, which results in a great disparity in solar radiation distribution and causes a great effect on the distribution of local solar energy supply over the rugged terrains. Furthermore, these distribution characteristics of solar energy can influence other meteorological elements such as temperature and humidity etc, which then causes a complex distribution further. At present, there are about only one hundred solar radiation observation stations in China. They are installed on horizontal planes without the sheltering of surrounding objects. And it's obvious that based on routine observed data it's impossible to get the spatially explicit distribution of solar radiation on rugged topography. Therefore, we need develop a series of distributed models using principles of direct and diffuse solar radiation on tilted surfaces to study on solar radiation distribution over heterogeneous surfaces.According to the principles of solar radiation on tilted surfaces, with GIS software as data processing platform and DEM data as input , the influence of geographical factors , such as azimuth and slope angle of titled surfaces, the screening effect of surrounding terrains and heterogeneous surfaces, on the solar radiation was figured out .The model of topography openness was improved and surface albedo through satellite observation was taken into account in this study. Based on parameters of clearness index k, and direct transmittance k), etc., with different monthly observational data sets of solar radiation and routine meteorology stations from 1957-2001, a series of solar radiation models of different temporal and spatial scales were developed over heterogeneous surfaces, such as astronomical solar radiation, direct and diffuse solar radiation, terrains reflected solar radiation from surrounding topography and global solar radiation, which go on with the geometric character between sunray and topography. And the distribution of the solar radiations spatial distributions from January to December were mapped with resolution of 1km x 1km.In this study, solar radiation simulations for heterogeneous surfaces were achieved by the observational data of solar radiation routine meteorology stations, which gived a useful attempt onsolar radiation simulation for heterogeneous surfaces and furnishes a new line of thoughts to data extension in spatial for other meteorological elements. The proposed models were proved to be able to treat volumes of data and are applicable to satellite image processing platforms or GIS, which gives a paradigm for the integration of GIS and atmospheric science and enlarges the application scope of GIS. The radiation data are provided in the same way as other kinds of spatial information and can be employed as basic geographic data for many fields such as agriculture, forestry, meteorology, hydrology, remote sensing, building industry, solar engineering and other relevant studies as well, therefore has a promising prospect.