Increase in Intensity, Frequency and Duration of Heat Waves in Porto Alegre, Brazil From 1961 To 2018

Authors: Thiago Pereira Rosa*, Centro Polar e Climático/Departamento de Geografia - UFRGS, Francisco Eliseu Aquino, Centro polar e Climático/Departamento de Geografia - UFRGS, Pedro Teixeira Valente, Centro Polar e Climático/Departamento de Geografia - UFRGS, Pedro Amaral Reis, Centro Polar e Climático/Departamento de Geografia - UFRGS
Topics: Hazards and Vulnerability, Global Change, Climatology and Meteorology
Keywords: Climate Change, Extreme events, Heating, Surface temperature.
Session Type: Guided Poster
Day: 4/3/2019
Start / End Time: 4:30 PM / 6:10 PM
Room: Roosevelt 3.5, Marriott, Exhibition Level
Presentation File: No File Uploaded

Heat waves (HW) are natural hazard that impact health, environment, services and infrastructure according to the WMO and the WHO. This study identified the occurrence of HW in Porto Alegre, Brazil, from 1961 to 2018, using the daily data of minimum temperature (Tmin), maximum (Tmax), ambient dry bulb temperature (DBT) and relative humidity (RH). Data was collected by the automatic weather station (WMO 83967) located in Porto Alegre (Lat 30°3'12"S, Long 51°10'29"W, 46.97m), available in the Meteorological Database for Teaching and Research of the Brazilian National Institute of Meteorology. Two methodologies were used to identify the HW: 1) Fixed indices for Tmin>22°C (71.6°F), Tmax>33°C (91.4°F) with at least 3 consecutive days between 1961 and 2018; 2) Heat Index (HI) used by the National Weather Service/NOAA was calculated for each day of the period 1961-2018 and was considered as a hot day HI> 27.5°C (81.5°F). A positive trend (R²=0.8602) was observed in the occurrence of HW when compared to previous series to Porto Alegre (1912-1948 to 1961-2018). We found an increase in frequency (+27.73%) of HW when comparing with the 1961-1990 and 1991-2018 periods; and also, 50.75% increase of in the HW number of days in the period 1961-1970 to 2011-2018, and an increase of 0.45°C (32.8°F) in the 1991-2018 mean temperature series when compared to 1961-1990. These results agree with HW future scenarios predicted by the Brazilian Panel of Climate Change and the IPCC evaluations resulting from the increase of extreme events due to anthropogenic forced climate changes.

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