Ondas de calor e (des)conforto térmico em Dourados (MS) em 2020

Abstract

The climate studies in urban areas have been justified by their process and expansion, this condition is also cited as a factor capable of aggravating impacts resulting from extreme events such as droughts, floods and heat waves.This research work aimed to identify and analyze the occurrence of temperature extremes - Heat Waves (HW) - and thermal discomfort at different points in Dourados (MS), where different structures and socioeconomic conditions were observed. Was used hourly and daily data collected with data logger-type equipment in the urban area and from the Meteorological Station Embrapa CPAO in the rural area from March 2020 to February 2021 were used. The daily data were used in the Intergovernmental Panel Changes Climates (IPCC) HW classification methodology, which considers a period of five days or more with a maximum temperature higher than the average maximum temperature added to 5°C. The average maximum temperature in the study area is 29.40°C, plus the 5°C indicated in the methodology, the limit value of 34.10°C was defined. The picture of occurrences of HW between the years 1980 to 2019 was also raised, observing the frequency and intensity of these events in the study area. While the hourly data were used to calculate the daily average and apply the Thom Thermal Discomfort Index (ID), adapted by Gilles et. al. (1990). This index verified the existence and behavior of episodes of thermal discomfort during the research and possible correlations between the results and the sampled points and thery characteristics. The results identified 75 heat waves throughout the period and indicated an increase in the number of occurrences and duration of HW. An increase of 77.8% was observed when the period was divided into two moments, from 1980 to 1999 and from 2001 to 2019, that is, an rise in the frequency of these events. As for the episodes of HW at the points sampled in 2020, it was observed that urban areas had more intense and longer-lasting episodes compared to the point in rural areas. Still on this relationship, these points had higher average temperature and lower relative humidity. This difference was also observed in the results of the application of the ID, since only in the urban areas were classes of strong and dangerous discomfort registered. There are also differences between the points. The point 1, located in the downtown and with high-income variables and more urban afforestation, had a less registers of the classe of strong discomfort compared to points 2 and 3 located in urban subdivisions on the periphery of the study area.. Through the results presented, we seek to justify the need for future studies on the impacts of this type of event on the population, considering the socioeconomic aspects in the analysis of thermal discomfort and the risks associated with it. There is a consensus on the vulnerability of groups such as the elderly and children when exposed to these episodes, however, the vulnerabilities related to social and economic conditions need attention, as this population has difficulties in accessing devices to mitigate the effects of high temperatures and has been living , in the case of Dourados, in places where the effects of these climatic variables are amplified.