Utilizing Geographic Information Systems Techniques to Study Solar Radiation Variations in Iraq for the Period (2008-2022)

Abstract

Calculating net solar radiation (Rn) is of great importance in various fields, including agriculture, the environment, and industry. Several methods are used to calculate Rn, including the direct method (composite net solar radiation (CNR4)) and the indirect method using several empirical equations that depend primarily on temperature and astronomical location. The primary objective of this research is to calculate and evaluate changes in net solar radiation values for Iraq during the period 2008-2022, using several variables such as (Rnl, Rns, Rso, Rs, Ra, and ea). The secondary objective is to determine the nature of the relationship between Rn and Tmax.

The results showed that Rn values in the northern regions of Iraq are consistently lower than in the central and southern regions, due to Iraq's high latitude and continental climate. The criterion Rn for Iraq was determined by averaging the most appropriate values from the studied stations that cover Iraq approximately equally. The year 2013 recorded the lowest solar radiation readings, while 2021 recorded the highest. Furthermore, this work demonstrates that net solar radiation controls daytime air temperature and is a major contributor to the temperature increase in Iraq, as every change in Rn behavior is accompanied by a corresponding change in Tmax. The results showed a positive linear relationship between Rn and Tmax.