Análise espacial do estresse térmico humano em momento de onda de calor: modelagem multiescala em cidade costeira de baixa latitude

Abstract

Heatwaves are sporadic meteorological phenomena characterized by an increase in air temperature over a large area, generally causing high thermal stress in urban populations. Additionally, the morphological and thermal characteristics of the urban surface can intensify the rise in air temperature. In Brazil, particularly in the Northeast region, the increasing duration and frequency of these extreme heat events have been documented by several studies. However, research on the impact of heatwaves on human thermal stress at the city scale, considering microclimatic, urban, and human aspects, remains scarce. Within this context, this research aims to assess the spatial variability of human thermal stress resulting from a heatwave in the city of João Pessoa through high-resolution mapping of the PET thermal comfort index. The proposed method identifies heatwaves based on maximum and minimum air temperature data (combined threshold) and employs numerical modeling at mesoscale and microscale, using the WRF and UMEP models, respectively, to estimate the meteorological and spatial data required for PET index calculations at the microscale. By analyzing the historical series from 2010 to 2023, this study identified the occurrence of extreme heat events over the study period, with an average duration of 3.8 days, a frequency of 1.45 events per year, and an average intensity of 1.37°C. During a case study of a heat wave, the mesoscale WRF model indicated that air temperature (°C) and relative humidity (%) showed gradients of 2.29°C and 19.21 percentage points, respectively, across the city. However, the results of the UMEP microclimatic model revealed high average values of mean radiant temperature (above 40°C) and areas of wind stagnation in some neighborhoods, negatively impacting thermal comfort in parts of the city. The PET (°C) index mapping data revealed a high thermal amplitude over João Pessoa (15.06°C) on extreme heat days, with a maximum value of 41.95°C. These findings indicate that, during a heatwave, different patterns of urban land use and occupation in João Pessoa can intensify population thermal stress, even in areas where the highest air temperature values were not observed. Finally, based on the 2022 census data, it was found that 34.58% of the local population resides in sectors with a high degree of positive thermal stress. Identifying areas most susceptible to extreme heat caused by heat waves is crucial for urban planners and policymakers to enhance city resilience and protect public health against increasingly frequent and intense extreme heat events.