Analysis of Urban Heat Island and Heat Waves Using Sentinel-3 Images: a Study of Andalusian Cities in Spain

David Hidalgo García

doi:10.1007/s41748-021-00268-9

Abstract

At present, understanding the synergies between the Surface Urban Heat Island (SUHI) phenomenon and extreme climatic events entailing high mortality, i.e., heat waves, is a great challenge that must be faced to improve the quality of life in urban zones. The implementation of new mitigation and resilience measures in cities would serve to lessen the effects of heat waves and the economic cost they entail. In this research, the Land Surface Temperature (LST) and the SUHI were determined through Sentinel-3A and 3B images of the eight capitals of Andalusia (southern Spain) during the months of July and August of years 2019 and 2020. The objective was to determine possible synergies or interaction between the LST and SUHI, as well as between SUHI and heat waves, in a region classified as highly vulnerable to the effects of climate change. For each Andalusian city, the atmospheric variables of ambient temperature, solar radiation, wind speed and direction were obtained from stations of the Spanish State Meteorological Agency (AEMET); the data were quantified and classified both in periods of normal environmental conditions and during heat waves. By means of Data Panel statistical analysis, the multivariate relationships were derived, determining which ones statistically influence the SUHI during heat wave periods. The results indicate that the LST and the mean SUHI obtained are statistically interacted and intensify under heat wave conditions. The greatest increases in daytime temperatures were seen for Sentinel-3A in cities by the coast (LST = 3.90 °C, SUHI = 1.44 °C) and for Sentinel-3B in cities located inland (LST = 2.85 °C, SUHI = 0.52 °C). The existence of statistically significant positive relationships above 99% (p < 0.000) between the SUHI and solar radiation, and between the SUHI and the direction of the wind, intensified in periods of heat wave, could be verified. An increase in the urban area affected by the SUHI under heat wave conditions is reported.Graphical

Highlights

In recent decades, numerous studies warn that the transformation of the landscape owing to the expansion of urban areas is one of the processes that contributes most to climate change (Li et al 2011; Carvalho et al 2017; Jiang et al 2019; Yang et al 2019; Song et al 2020)
The Land Surface Temperature (LST) and Surface Urban Heat Island (SUHI) were studied by analyzing Sentinel day and night images of the eight capitals of Andalusia both in periods of normal environmental conditions and in periods of heat wave, during the years 2019 and 2020
Our results detect mean LSTs based on Sentinel day and night in inland cities—both under normal environmental conditions and in periods of heat wave—that are higher than the mean LSTs of coastal cities

Summary

Introduction

Numerous studies warn that the transformation of the landscape owing to the expansion of urban areas is one of the processes that contributes most to climate change (Li et al 2011; Carvalho et al 2017; Jiang et al 2019; Yang et al 2019; Song et al 2020). Changes in land cover increase the surfaces of impermeable materials, such as asphalt and concrete, reducing evapotranspiration (Stewart and Oke 2012) These materials are known to store the heat coming from solar radiation and subsequently release it into the atmosphere (Arnfield 2003; Zhou et al 2015; An et al 2020). Episodes of increased anthropogenic heat are known to be among the natural phenomena having the greatest social, economic and environmental impact (An et al 2020) They imply more consumption of electricity and water in homes (Valor et al 2001), and increased morbidity and mortality (Semenza et al 1996; Poumadère et al 2005; Jiang et al 2019; An et al 2020). Proof can be found in the heat wave of Chicago in 1995, which caused 800 deaths (Semenza et al 1996), that of the summer of 2003 in Europe, when 70,000 people died (Robine et al 2008), the one occurring in Russia during the summer of 2010 (Grumm 2011), that of eastern China in 2013 (Xia et al 2016), or Northwestern USA and Western Canada (Lytton) in 2021, with temperatures over

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