Estimation and Comparison of the Clearness Index using Mathematical Models - Case study in the United Arab Emirates

An accurate knowledge of the properties of solar radiation has a fundamental importance to study and to design solar energy systems. The clearness index plays a key factor in providing information about the transmitted solar radiation through the atmosphere compared to the extraterrestrial solar radiation. It plays a major role in understanding the meteorological phenomena, variations in the atmosphere, and sky conditions. However, the astronomical calculation requires a geographical consideration and precise measurement of the solar radiation. This study carried out an evaluation of the clearness index by applying mathematical approaches, a multiple linear regression function and a neural network approach, to the accumulated data of solar radiation, monthly temperature variation, humidity, and pressure of Dubai and Abu Dhabi meteorological stations in the United Arab Emirates.