Caracterização de ilhas de calor e conforto térmico em áreas urbanas do semiárido brasileiro.

Abstract

This study aimed to identify heat islands (HI), determine the thermal discomfort level and evaluate the influence of tree planting on the microclimate in urban areas of the Brazilian semiarid. Field activities were divided into three phases, obtaining data from automatic weather stations installed in municipalities of Mossoró-RN, Serra Talhada-PE, Petrolina-PE and Juazeiro-BA during the wet period (05/12/2007 to 05/26/2007) and dry period (11/15/2008 to 12/05/2008). In the second phase, data were collected in Petrolina-PE throughout the year 2012. The third phase evaluated the influence of tree planting in the urban microclimate in Juazeiro-BA during the dry period (10/24/2012 to 11/09/2012). Heat islands were characterized by differences in air temperature between urban and rural environments in the cities surveyed, while thermal discomfort was determined by adapting the calculation proposed by Thom of the thermal discomfort index (TDI), obtaining adjusted equations for maximum (TDIx) and minimum (TDIm) values of TDI. Finally, the influence of tree planting on the microclimate was assessed by comparing climatic data area shaded and unshaded in Juazeiro-BA. The results indicated the existence of high intensity heat islands, especially HI = 5.3 °C on 04/28/2012 in urban area of Petrolina-PE, where, during the year 2012, the TDIx indicated thermal discomfort for seven months (occasionally form January to May and intensely from November to December) and partial comfort in the remaining months (June to October). However, in the rural area of the same city, the TDIx indicated thermal discomfort in only two months (November and December) and partial comfort from January to October. Regarding TDIm, the urban area of Petrolina-PE presented thermal comfort in four months of 2012 (mid-June to mid-October), whereas the remaining months were characterized by partial comfort. In the rural area, TDIm indicated that thermal comfort was occasionally detected from February to May and intensely detected from June to October, while the other months were characterized by partial comfort. It was evident that the constituent elements of the urban area effectively contribute to the formation and expansion of heat islands bringing thermal discomfort to its inhabitants. The results also suggest that urban trees can be an effective way to mitigate the thermal discomfort characterized in the surveyed cities. Keywords: urban and rural areas, air temperature