Investigating Surface Urban Heat Islands in South America Based on MODIS Data from 2003–2016

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.

The Impact of the Land Cover Dynamics on Surface Urban Heat Island Variations in Semi-Arid Cities: A Case Study in Ahmedabad City, India, Using Multi-Sensor/Source Data

“…Consequently, a SUHI characterization over Ahmedabad in a semi-arid climate during summer daytime was provided. This negative SUHI effect during daytime is reported for some urban areas of north-western China [53], the western United States [54], central Asia [55], and South America [20]. All these areas are situated in arid or semi-arid regions, a climate rather similar to the pre-monsoon summer season in Ahmedabad, where the presence in the rural area of large zones of bare croplands with very low vegetation covers and soil moisture reduces cooler transpiration effects [22,55,56].…”

“…The population growth, acting as an indicator of the built-up sprawl, positively impacts the SUHII only in winter daytime and summer nighttime. In [20], SUHI in South American arid cities exhibited an insignificant correlation with the population both day and night for all seasons. A positive impact of WT on SUHI means that urban warming causes greater water consumption in the city.…”

“…For a specific parameter, the variable correlations suggest how a driver can have significant effects or not on SUHI depending on the season and time. Such variations are also different depending on the arid city’s location [20,32]. Also, other important variables may influence SUHI, such as thermal inertia and soil moisture, which were not considered in this study due to a lack of data.…”

“…Arid and semi-arid cities exhibit an inversion of the typical SUHI phenomenon in daytime, with the city core appearing cooler compared to the suburbs and rural surroundings [16]. Cooling effects have been found in arid cities during the summer months in different parts of the world [17,18,19,20].…”

Spatial Configuration and Extent Explains the Urban Heat Mitigation Potential due to Green Spaces: Analysis over Addis Ababa, Ethiopia

“…Changes in land use and land cover result in an abundance of built impervious surfaces and depletion of green vegetation covers, causing alterations in the surface energy fluxes [6][7][8][9], distribution and composition of biodiversity [10,11], increasing anthropogenic heat releases [12], and human health [13,14]. As a result, how to understand and mitigate these adverse impacts has become a key study topic in urban ecology, geography, and climatology [15][16][17][18].…”