Modelling Topographic Variation In Solar Radiation In A GIS Environment

Data of solar radiation is needed by many research . But measurement of it by radiation measuring instrument in research area will cost a lot ; using empirical relationships will need many atmospheric and topographic parameters which are not readily available. In this research, we integrate solar radiation model into GIS, Modelling topographic solar radiation in GIS environment. The model presented here only uses a digital elevation model(DEM) to compute direct solar radiation,time of irradiation and simply diffuse radiation. Data of surface gradient(slope) and orientation(aspect) and shading by adjacent features is derived from digital elevation model.In this paper a new arithmetic of shading is put forward.There is a hypothesis of the model that sky is clear,many atmospheric parameters are not taken into account,such as cloud cover and precipitable water content of the atmosphere.Through verifying ,the reliability of the result of flux of direct radiation and time of irradiation from the model is more than 90%. The result of the model is displayed by digital models that we can directly recognize the distrbution of solar radiaton of study area.The algorithm of the model is efficient.The model has been successfully run in ViewGIS .