Forecasting Solar Irradiance Using NWP Models: An Evaluation Study in Andalusia (Southern Spain)
Abstract
In this work, results of a study about the role of the spatial averaging of the WRF model DNI and GHI forecasting errors are presented. The study was conducted for two stations located in the region of Andalusia (southern Spain) along the period 2007 and 2008. Firstly, WRF three days ahead GHI and DNI forecasts, with 3 km of spatial resolution, were analyzed. Secondly, these forecasts were spatially averaged, in a post processing procedure, in increasing areas of up to 24 km x 24 km. Results showed that the spatial averaging increased notably the reliability of the WRF estimates in terms of the RMSE. For instance, for 24-hours-ahead forecasts and during summer, relative RMSE improved from 22%, when the evaluation station location grid point is considered (3 km x 3 km), to 15%, when averaging over the nearest 9 by 9 grid points (24 x 24 km).