Babak Jahani, PhD student of Dr. Josep Calbó, has published the paper entitled “A comparison between the application of empirical and ANN methods for estimation of daily global solar radiation in Iran”, in collaboration with other researcher from the College of Hydrology and Water Resources, Hohai University (China). This paper has been published in the Theoretical and Applied Climatology journal.

Theoretical and Applied Climatology offers the latest and most significant developments from studies around the world in climate, atmosphere and meteorology. The journal covers climate modelling, climatic changes and climate forecasting, micro- to mesoclimate, applied meteorology as in agro- and forest-meteorology, biometeorology, building meteorology and atmospheric radiation problems as they relate to the biosphere; effects of anthropogenic and natural aerosols or gaseous trace constituents; hardware and software elements of meteorological measurements, including techniques of remote sensing, among other topics of current interest.

In this paper, the authors aim to provide a comparison between the performance and suitability of different types of models for estimation of daily global solar radiation in Iran, based on duration of sunshine hours and diurnal air temperature. These models consist of empirical, ordinary ANN, and ANN models coupled with genetic algorithm (so called coupled ANN models). The models’ performance was evaluated and compared based on the error statistics root mean squared error (RMSE), mean bias error (MBE), and coefficient of determination (R²). The empirical models (median of R², MBE, RMSE for AP 0.93, 37.0, and 179.3 J/cm²/day) could generally perform much better than the ordinary ANN models (median of R², MBE, RMSE for MLP(n) 0.90, 55.7, and 243.5 J/cm²/day). The performance of the ordinary ANN models was improved considerably after being coupled by genetic algorithm (median of R², MBE, RMSE for MLP-GA(n) 0.92, 38.4, and 185.5 J/cm²/day), making them the most accurate models at most of the stations studied. However, the difference between the overall performances of these coupled ANN models and empirical ones was slight. Lastly, despite the coupled ANN models had relatively better accuracy compared to the empirical ones, when taking different metrics such as the required processing time, skill, and equipment into account, the empirical models appear to be the most suitable models for estimation of daily global solar radiation in Iran.

This research was conducted within the “Clouds, Radiation to the Atmosphere and Climate” research line of the Environmental Physics group.

The Islamic Republic of lran Meteorological Organization (IRIMO) provided the required data.