Urban Heat Island Formation in Greater Cairo: Spatio-Temporal Analysis of Daytime and Nighttime Land Surface Temperatures along the Urban–Rural Gradient

Abstract

An urban heat island (UHI) is a significant anthropogenic modification of urban land surfaces, and its geospatial pattern can increase the intensity of the heatwave effects. The complex mechanisms and interactivity of the land surface temperature in urban areas are still being examined. The urban–rural gradient analysis serves as a unique natural opportunity to identify and mitigate ecological worsening. Using Landsat Thematic Mapper (TM), Operational Land Imager/Thermal Infrared Sensor (OLI/TIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS), Land Surface Temperature (LST) data in 2000, 2010, and 2019, we examined the spatial difference in daytime and nighttime LST trends along the urban–rural gradient in Greater Cairo, Egypt. Google Earth Engine (GEE) and machine learning techniques were employed to conduct the spatio-temporal analysis. The analysis results revealed that impervious surfaces (ISs) increased significantly from 564.14 km2 in 2000 to 869.35 km2 in 2019 in Greater Cairo. The size, aggregation, and complexity of patches of ISs, green space (GS), and bare land (BL) showed a strong correlation with the mean LST. The average urban–rural difference in mean LST was −3.59 °C in the daytime and 2.33 °C in the nighttime. In the daytime, Greater Cairo displayed the cool island effect, but in the nighttime, it showed the urban heat island effect. We estimated that dynamic human activities based on the urban structure are causing the spatial difference in the LST distribution between the day and night. The urban–rural gradient analysis indicated that this phenomenon became stronger from 2000 to 2019. Considering the drastic changes in the spatial patterns and the density of IS, GS, and BL, urban planners are urged to take immediate steps to mitigate increasing surface UHI; otherwise, urban dwellers might suffer from the severe effects of heatwaves.

Urbanization Impacts on Evapotranspiration Across Various Spatio‐Temporal Scales

“…Note that a 25 km buffer size in this analysis was centered around a point feature (circle in Figure 1f) while the buffer area from the other analyses was an extension of urban raster cells with a size of 10 km (i.e., selecting raster cells within 10 km of MODIS urban grid cells; black/orange cells in Figure 1). The choices of these buffer sizes are adapted from UHI studies (Athukorala & Murayama, 2021; Rasul et al., 2015).…”

Workers’ Satisfaction vis-à-vis Environmental and Socio-Morphological Aspects for Sustainability and Decent Work

“…Land surface temperatures can be affected by error ratios because of the calibration noises in Landsat 8 Band 11 and the reliance on Band 11 measurements [16,51,52]. Hence, the average of the two bands' mean brightness temperatures was used as the average temperature.…”

Past and Future Impacts of Urbanisation on Land Surface Temperature in Greater Cairo Over a 45 Year Period

“…These changes have been related to land use/ land cover, where the urban growth in the high density population areas as Greater Cairo showed the greatest increase in thermal radiation from land surfaces (Abutaleb et al, 2015). Recent studies (Athukorala and Murayama 2021) have shown differences in LST along an Urban-rural gradient, between the day and night, and the spatial characteristics of nighttime surface urban heat island effects over Greater Cairo. However, the long-term changes of LST have not been studied, and relatively little attention has been given to specific urban land covers that exacerbate heating or provide cooling.…”