Modelling global solar radiation to optimise agricultural production

Aim of study: To present a complete global radiation model that includes direct, diffuse sky and ground-reflected radiation, and compare the values with those obtained by the pyranometers.Area of study: The data were analyzed at the meteorological station network in Extremadura, Spain, to validate the results calculated by the model.Material and methods: The method uses the maps from meteorological station data are based on a single piece of daily solar radiation data for an area of 8,000 to 9,000 ha, whereas the maps created by the models are obtained using the spatial resolution of the digital elevation model, in this case 25 × 25m.Main results: The analytical model used in the study obtained global radiation values with a difference of 1.44% relative to the values captured by the meteorological stations in Extremadura. Analysis of the data indicates that on days with a specific type of fog or very diffuse cloud, the global radiation captured by sensors is greater than it would be on clear-sky days in the same area. The method was suitable for calculating global solar radiation on any type of terrain with its corresponding diversity of crop types.Research highlights: The research highlights the importance of understanding and modelling solar radiation for efficient use of water resources in agriculture. Adding these global radiation models to a GIS would provide a very valuable tool for developing regions.