Seasonal and daily effects of the sea on the surface urban heat island intensity: A case study of cities in the Caspian Sea Plain

This study aimed to explore the effect of the sea on the spatial and temporal changes in surface urban heat island (SUHI) intensity. Therefore, 11 cities located along the Caspian Sea Plain were selected as the case studies. Firstly, the SUHI intensity of both coastal and non-coastal cities was calculated for different seasons and times of day and night. Finally, the effect of distance from the sea on the SUHI intensity was calculated by modeling the relationship between the SUHI intensity and a set of independent parameters such as urban surface biophysical properties, population density, and distance from the coastline. The results showed that by increasing the distance of cities from the sea, the daily SUHI intensity increased, while it reversed during the night. The RMSE values between the actual and simulated SUHI intensities based on population density and surface biophysical properties in spring, summer, autumn, and winter were 0.9, 1.1, 0.5, and 0.3 °C, respectively. By factoring in the distance from the sea in the modeling, the RMSE values for different seasons were obtained at 0.7, 0.8, 0.3, and 0.2 °C, respectively. The results show that distance from the sea has a significant effect on UHI intensity.