Predicting urban thermal comfort from calibrated UTCI assessment scale - A case study in Belo Horizonte city, southeastern Brazil

Silva, Thiago José Vieira; Hirashima, Simone Queiroz Silveira

doi:10.1016/j.uclim.2020.100652

Cited by 27 publications

(8 citation statements)

References 31 publications

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“…Therefore, while thermal conditions in southern Africa are on average largely classified as thermophysiologically acceptable by global standards, they, and especially the large degree of day-time heat stress and night-time cold stress experienced, might not be suitable in the context of a population spending more time outdoors, and with less infrastructural amelioration; with less infrastructural amelioration, and due to limited availability of resources, day-time activities (and in particular those outdoors) have limited availability of adaptation and mitigation strategies against heat stress, for instance (Ncongwane et al, 2021). There may, thus, be a need for more regional-specific tuning of the UTCI thermal classifications to consider the thermal comfort of people taking part in activities more common to southern Africa; as has been suggested for China (Ge et al, 2017) and South Korea (Shin et al, 2022), and similar to the regional-specific tuning undertaken in Belo Horizonte city in southeastern Brazil (Silva and Hirashima, 2021). Nonetheless, foundational work has demonstrated the universal nature of the UTCI, highlighting that it is more sensitive to changes in ambient stimuli (e.g., temperature, relative humidity, solar radiation, and wind conditions, all of which are included in the index), depicts temporal variability of thermal conditions better than other indices, and is valid at all spatiotemporal scales and not only specific meteorological and geographical situations (Błażejczyk et al, 2012;Jendritzky et al, 2012).…”

Section: Discussionmentioning

confidence: 96%

Spatiotemporal characteristics of human thermal comfort across southern Africa: An analysis of the Universal Thermal Climate Index for 1971–2021

Roffe

Walt

Fitchett

2023

Intl Journal of Climatology

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The 6th Assessment of the Intergovernmental Panel on Climate Change projects increasing thermal-associated morbidity and mortality under anthropogenically induced warming. Over 100 indices exist to quantify thermal stress, and among these, the Universal Thermal Climate Index (UTCI) was developed for regional investigations of thermal stress influences on human health. Although by definition a universal index, current applications are mainly limited to Europe. For regions such as Africa, use of the UTCI has been hampered by a lack of available requisite input variables from ground-based meteorological stations. To overcome this, a gridded dataset, derived from ERA5 reanalysis, of UTCI equivalent temperatures was developed by the European Centre for Medium-Range Weather Forecasts. Using this dataset for daily average, minimum and maximum UTCI values, we explore spatiotemporal patterns and changes thereof over annual, seasonal, and monthly scales across southern Africa from 1979 to 2021. Across these scales, 9 of 10 UTCI thermal stress categories were observed, ranging from very strong cold stress to extreme heat stress. Spatially, no thermal stress was most widespread for daily mean values, whereas for daily maximum (minimum) values there was a wider heat (cold) stress incidence, with frequent occurrences of moderate and strong heat stress (slight and moderate cold stress). Interannually, a clear El Niño-Southern Oscillation influence on thermal stress was evident during summer, with El Niño (La Niña) phases extending (reducing) heat stress incidences by up to 13.8% (2.9%). Over the study period, heat stress increased at statistically significant rates in many instances, with the strongest, most widespread increases, for the daily average and maximum (minimum), during spring (summer), averaging 0.28 and 0.29 CÁdecade −1 (0.23 CÁdecade −1 ); few regions experienced statistically significant decreasing trends. Overall, the trend results highlight regions vulnerable to significant thermal climate changes, and thus should be considered in decision-making regarding outdoor activities.

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Section: Discussionmentioning

confidence: 96%

Spatiotemporal characteristics of human thermal comfort across southern Africa: An analysis of the Universal Thermal Climate Index for 1971–2021

Roffe

Walt

Fitchett

2023

Intl Journal of Climatology

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“…However, systematic errors are common amongst current reanalyses and are mostly related to resolution issues. Thus, it is important to work on the further development of better local calibrations, as suggested by Silva and Hirashima (2021). A comparison between different indices should also be encouraged as different heat stress levels vary depending on how temperature and humidity are considered in the equations (Freychet et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

“…However, few studies globally analyzed thermal comfort indexes such as UTCI and heat stress based on gridded data (Di Napoli et al, 2018;Antonescu et al, 2021). In the case of SA, the overwhelming majority of studies using UTCI rely on single-point analysis using in-situ data and are limited to a few regions in Brazil, namely the main cities (Silva and Hirashima, 2021).…”

Section: Introductionmentioning

confidence: 99%

Heat stress in South America over the last four decades: a bioclimatic analysis

Miranda

Santos

Peres

et al. 2023

Preprint

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The observed continuous rise in the frequency of extreme heat events in South America (SA) poses a serious challenge for public health. However, there is a lack on the understanding of the large-scale and long-term variability and trends of thermal stress in this continent. Accordingly, here we developed the first comprehensive bioclimatology of thermal stress over SA during the past four decades. Consecutive heat stress hours were analyzed using the Universal Thermal Climate Index (UTCI) from ERA5-HEAT reanalysis according to the Köppen–Geiger climate classification and also focusing on the 31 most populated cities of SA. Results show an inland/coastline contrast and a marked latitudinal northward increase in the number of hours under heat stress. Heat stress hotspots are located mostly around the Amazon, northern and central parts of SA with 26–35% of the hours between 1979 and 2020 under strong heat stress. The annual number of hours within heat stress increased significantly between 1979 and 2020, varying from + 1.16 hour/year to + 8.25 hour/year depending on the Köppen–Geiger class. The past 20 years (2000 forward) presented not only more consecutive hours under heat stress than the previous two decades in all the analyzed cities, but also a higher persistence of such extremes. The bioclimatology of thermal stress developed here may provide important guidelines to decision-makers for exploring adaptation strategies to increase societal resilience.

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“…This definition leaves open what is meant by the condition of mind or satisfaction, but it correctly emphasizes that the judgment of comfort is a cognitive process involving many inputs influenced by physical, physiological, psychological, and other processes [4][5][6]. Different approaches are used to assess the outdoor thermal comfort in cities characterized by different climates (e.g., Brazil [7], Hong Kong [8], The Netherlands [9], Spain [10], and other European cities [11], United States [12], and India [13]). As is well known, built areas alter the local surface energy balance, impacting micrometeorological variables (e.g., air temperature and humidity) and local atmospheric circulation, with consequences for pedestrian comfort conditions.…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Study of Summer Thermo-Hygrometric Comfort under Different Environmental Conditions in a Mediterranean City

et al. 2022

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The thermo-hygrometric sensation of pedestrians in outdoor environments can be quantified by means of bioclimatic indices. In this work, the Mediterranean Outdoor Thermal Comfort Index (MOCI) is applied in the city of Rome (Italy) for the purpose of investigating the effect of local environmental conditions (urban, suburban, rural) on pedestrian thermal comfort. Hourly values of MOCI are calculated for the May–September period in the years 2015–2021 using weather quantities acquired by the four monitoring stations of the Regional Agency for Environmental Protection included in the metropolitan area of Rome. MOCI data are analyzed based on the comfort and (cold/hot) discomfort conditions during both daytime and nighttime. At the urban station, 26% of daily records exceed the comfort threshold revealing the effect of urban overheating, whereas only 0.1% of hot discomfort occurrences are recorded overnight. Here, greater nighttime thermal comfort is experienced than in non-urban locations suggesting that the nocturnal thermo-hygrometric conditions are satisfactory for inhabitants in downtown Rome, despite the urban heat island. It also suggests that other factors, such as orography and atmospheric circulation, influence outdoor thermal comfort. The development of this work will therefore include at least these two elements.

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Predicting urban thermal comfort from calibrated UTCI assessment scale - A case study in Belo Horizonte city, southeastern Brazil

Cited by 27 publications

References 31 publications

Spatiotemporal characteristics of human thermal comfort across southern Africa: An analysis of the Universal Thermal Climate Index for 1971–2021

Spatiotemporal characteristics of human thermal comfort across southern Africa: An analysis of the Universal Thermal Climate Index for 1971–2021

Heat stress in South America over the last four decades: a bioclimatic analysis

A Preliminary Study of Summer Thermo-Hygrometric Comfort under Different Environmental Conditions in a Mediterranean City

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