Abstract
The phenomenon of urban heat islands (UHI) is caused by the increase in temperatures of an urban area as a result of the development of human activities within that area, this phenomenon is usually studied in medium and large cities. This study aims to verify if the phenomenon of UHI occurs in the municipality of Três Rios – RJ, a small sized city. This study included the use of mobile transect, through pre-established data collection points/stations. Five data collection points were selected, from which one was included in a rural area, one in the Parque Natural Municipal (Urban Park, within the city), and three points within the urbanized area. The equipment used was the Brunton® / ADC PRO handheld weather station. The data collection period ranged from September 2018 until July 2019, which included the four seasons. Measurements were taken at 6:00, 12:00, 15:00, 18:00, and 21:00h, in alternate days during the study period. Considering the temperature measurements, two different indicators of thermal variability were used. Strong magnitude heat islands were detected, taking into consideration the relevant variation of maximum temperatures observed in the urban area when compared to the rural area. The results indicate the most affected populations to be the ones located within urban areas, mostly individuals under socioeconomic vulnerability. The results obtained can be used as support for the development of strategies to minimize the thermal discomfort to populations exposed to the influence of higher magnitude urban heat islands.
Highlights
Gunawardena et al (2017) explained that the energy absorbed by urban surface is related to solar radiation and to the anthropogenic heat generated, and that its balance is established by convection and humidity evaporation processes and by the configuration of the urban environment
The phenomenon of urban heat islands (UHIs) is characterized by an increase in temperatures in an urban area when compared to the surrounding rural areas, and this is considered a consequence of anthropogenic influence (Ward et al, 2016)
Analyzing the phenomenon of heat islands, in terms of an “urban energy balance,” the way energy enters and leaves a system considers that the solar radiation that enters the system is retained for a longer period on artificial surfaces when compared to natural surfaces (Oke, 1988; Gartland, 2010; Gunawardena et al, 2017)
Summary
Air temperature can be affected by the human interventions in a region, once urbanization creates a new space and shifts general environmental conditions, such as creating changes in energy flow (Fialho, 2009). Gunawardena et al (2017) explained that the energy absorbed by urban surface is related to solar radiation and to the anthropogenic heat generated, and that its balance is established by convection and humidity evaporation processes and by the configuration of the urban environment. Gunawardena et al (2017) explained that the energy absorbed by urban surface is related to solar radiation and to the anthropogenic heat generated, and that its balance is established by convection and humidity evaporation processes and by the configuration of the urban environment. The impacts of urban development on energy balance can define the climate within the cities, by not just causing thermal discomfort and affecting habitat conditions and human health (Oke, 1988). Considering this scenario, the increasing level of temperatures within urban areas can lead to the phenomenon of urban heat islands (UHIs). The formation of UHI is influenced by several factors, such as the reduction in wind circulation, as a consequence of tall buildings; atmospheric pollution; reduction in tree cover; reduction of humidity rates; and the emission of particles (Yow and Carbone, 2006)
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