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Urban heat islands (UHIs) exist when temperature in the atmospheric boundary layer is warmer above the urban area than it is above rural areas. Surface UHIs (SUHIs) exist when the temperature of the surface is warmer in urban areas than in rural areas. Several cities in arid climates have showed a weak or negative UHI and SUHI. In addition, UHIs and SUHIs have not been thoroughly studied in many arid environments around the globe, especially in cities of the Arabian Peninsula. By integrating Landsat remote sensing data and long-term air temperature data from 1985 through 2010, we analyzed changes in the SUHI and UHI to better understand their behavior in Riyadh City, Saudi Arabia. Signals of both UHI and SUHI sinks were found and significant decreasing trends were found in the mean annual nocturnal UHI, nocturnal UHI in winter and autumn, and in diurnal UHI during winter. Rural areas were found to exhibit warmer land surface temperatures (LSTs) than urban areas, which was evidence of the incidence of the SUHI sink in the study area. Within the built-up areas, the main road areas and surfaces in the east parts of the city exhibited higher LSTs in all the studied years.
Alghamdi et al. (Fri,) studied this question.