Spatial Variability of Urban Heat Islands in Cairo City, Egypt using Time Series of Landsat Satellite Images

Abstract

Global warming has obtained more attention because of increasing global mean surface temperature since the late 19th century. Urbanization is considered an important contributor to global warming in big cities. Cairo is one of the heavily populated cities in the world, which has rapid urbanization that resulted in remarkable temperature variation compared to the rural surrounding areas. This phenomenon is known as "Urban Heat Islands" (UHIs) that influence both local and regional climate, environment, and socio-economic development. In this research time series of satellite images were used to map the spatial variability of Land Surface Temperature (LST) and Heat Islands in Cairo city. Historical and contemporary record of Landsat images nearly 16 dates from 1990 to 2014 were used to retrieve LST and land cover categories. Results showed that LST was highly influenced by Land use and land cover changes; heat island effect was dominant in urbanized areas, bare/desert land and industrial zones (e.g. Shobra El-khema). The industrial zones, in particular, were possibly high due to the aluminum roof material plus the thermal energy from production activities and high emissions of air pollutants. The pattern of spatial distribution of heat islands has significantly changed from bare/desert land and built up areas (as warmer) to cultivated land and water bodies (as colder). To analyze the relationship between Heat Islands and land-cover changes a quantitative correlation between LST and Normalized Difference Vegetation Index (NDVI), Modified Normalized Difference Water Index (MNDWI) and Normalized Difference Build-up Index (NDBI) was employed. It was found that the correlation between LST and NDVI and MNDWI was negative with r 2 of 0.8 and 0.57 respectively; however, the correlation with NDBI was strongly positive with r 2 of 0.81. It is anticipated that the outcomes of this research will contribute to GEOSS for global integration and correlation.

Spatio-temporal variations of land surface temperature using Landsat and MODIS: case study of the City of Tshwane, South Africa

“…The results are in accordance with the consensus that there was higher LST in urban areas compared to the surrounding areas. This agrees with the finding from cities such as Cairo in Egypt, where there is little or no vegetation in urban areas (El-Magd et al, 2016). CoT is also known as the Jacaranda City a pseudonym that was derived from the Jacaranda trees in the streets together with other different indigenous and alien tree species.…”

“…where N is the pixel normalised value of the LST, Ti is the LST of the i th pixel, Tmin is the minimum value of the LST and Tmax is the maximum LST. The normalised LST can be divided into five zones, which are strong heat islands zone (0.8-1.0), heat islands zone (0.6-0.8), normal zone (0.4-0.6), green islands zone (0.2-0.4) and strong green islands zone (0-0.2) (El-Magd et al, 2016;Xu et al, 2013).…”

Investigation of Aerosol Climatology, Optical Characteristics and Variability over Egypt Based on Satellite Observations and In-Situ Measurements

“…In addition, in a study conducted by El-Metwally et al [35] on the impacts of aerosols on solar radiation transfer using AERONET data, it was concluded that the three dominant aerosol components in Egypt are (1) the highly absorbing aerosols produced by daily activities, (2) aerosols produced from burning agricultural wastes in the Nile delta region and (3) desert dust. Each of these aerosol components combine with human activities and lead to the occurrence of heat islands over Cairo, Abou, El-Magd, et al [39]. The purpose of this research is to intensively examine for the first time the temporal and spatial variations of atmospheric aerosols over Egypt from 2012 to 2018 using both MODIS Terra and AERONET data.…”

“…Various studies have used satellite data to observe atmospheric aerosol characteristics worldwide [4,20,21,[29][30][31][32][33][34]. In Egypt, research studies have been carried out on atmospheric aerosols with a particular focus on Cairo and the Nile delta region [33,[35][36][37][38][39][40][41][42] due to their high pollution load. Shokr [36] discussed aerosol characteristics over five Egyptian cities using MODIS Aqua aerosol data.…”

Mitigating Heat Islands Effect in Mega Cities through Districts' Prioritisation for Urban Green Coverage Applications: Cairo – Egypt as a Case Study

“…In summer 2012, land surface temperature (LST) varied from 27°C to 61°C [7]. The UHI intensity index in Cairo has five dominant levels, with least intensity in vegetated areas/water bodies, while highest in scattered bare land areas and industrial zones [9]. Thus, the above observations make it a necessity to develop means to determine the hot spots in Cairo Governorate, to prioritize and propose strategies for high temperatures mitigation.…”