Exploring the seasonal and annual nonlinear relationships between daily solar irradiance and maximum temperature in Iraq

Empirical relationships explore and understand an advanced effectively methodology for predicting maximum temperature (Tm) in regions with different climatic conditions based on solar irradiance (SI) readings taken from NASA/POWER for the period 2014–2024. Using seasonal and annual daily means, the SI-Tm correlations during the four seasons (winter, spring, summer, and autumn) and annual cycle were investigated in six cities (Basra, Shanafiya, Baghdad, Rutba, Kirkuk and Shakhan) in Iraq using quadrate and cubic polynomial regression models. These models provided strong fit lines between the data points for SI and Tm, which effectively capture the seasonal (R2>0.4 in winter and summer and >0.8 in spring and autumn) and annual daily Tm (R2 > 0.9) as a predictor variable. The results show that Iraq experiences high SI and extreme Tm, especially in the southern regions. In contrast, the northern provinces have lower SI and Tm values due to higher altitudes and increased weather activity. This study offers valuable information for policymakers and planners to highlight the potential for solar energy generation and distribution in accordance to climatic conditions.