Abstract
Surface urban heat islands (SUHIs) have been investigated in many regions around the world, but little attention has been given with regard to SUHIs in South America. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data was used to investigate the diurnal, seasonal, and interannual variations in the SUHI intensity (SUHII, the urban LST minus the rural LST) in 44 South American cities in different climate zones and types of rural land. To examine the effects of factors that may influence the SUHII, correlations between the SUHII and the enhanced vegetation index (EVI), urban area, population, altitude, and anthropogenic heat emissions were performed. The results showed that the SUHI effect was obvious in South America. The mean daytime SUHII was higher than the mean night-time SUHII in all areas except for the arid climate zone. In the daytime, the summer displayed a stronger SUHII in the warm temperate climate zone than the other seasons. The night-time SUHII showed less obvious seasonal variations. In addition, the surrounding land cover influenced the SUHII. During the day, the SUHII was therefore stronger in rural areas that were covered by forests than in other types of rural land. Interannually, most cities showed an insignificant temporal trend in the SUHII from 2003 to 2016. The daytime SUHII was significantly and negatively correlated with the ∆EVI (the urban EVI minus the rural EVI) across the 44 cities, but a poor relationship was observed at night. In addition, anthropogenic heat emissions were positively correlated with the night-time SUHII. Urban area, population, and altitude were weakly correlated with the SUHII, which suggested that these factors may not have a significant impact on the spatial variations in the SUHII in South America.
Highlights
Accompanying rapid urbanization, the proportion of the global urban population increased from 45% in 1995, to 54% in 2015, and it will reach up to 66% in 2045 [1]
Correlation analyses were conducted to reveal the relationships between the SUHII and ∆enhanced vegetation index (EVI), and urban area, population, altitude, and anthropogenic heat emissions
The results showed that the daytime SUHII values were higher than the night-time SUHII, except in the arid climate zone
Summary
Accompanying rapid urbanization, the proportion of the global urban population increased from 45% in 1995, to 54% in 2015, and it will reach up to 66% in 2045 [1]. A series of environmental problems caused by rapid urbanization have raised public concerns. One of these problems is the urban heat island (UHI) phenomenon, where the air temperature of an urban area is higher than that in nearby areas during the night [2]. UHI has negative effects on water and air quality [3], net primary productivity [4], biodiversity [5], human health [6,7,8], and climate [9,10,11,12,13]. The air UHI effect is considered to be more closely related to human health, both types of UHI are still highly related to health [9,15,16]. It is of great importance to understand the driving mechanism and ecological effects of SUHI on regional and global scales
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