Análise temporal da temperatura de superfície na área urbana do município de Caxias do Sul - RS

Abstract

Urban expansion is a global phenomenon that has the consequence of increasing the rate of urbanization in the cities. This factor causes a temperature of densely urbanizes centers to be higher than the green areas represented mainly by parks, tree-lined streets and even lakes. In this sense, this work was analyzed by the temperature of the urban area of Caxias do Sul-RS through the use of remote sensing data, in the years 1993 and 2017 year for the aforementioned dates. Initially the land use maps were elaborated for both years, discriminating five classes of use, one knowledge: forest, agriculture, naked soil, urbanization and water depth. Afterwards, the effects of the atmosphere were corrected and, afterwards the images were translated to the surface temperature. The results indicate an increase of about 110% in the extension of the urban areas during the studied period, with an increase, less expressive, in the area of water depth. As other classes were decreasing of their areas, justified by the advance of urbanization. For surface temperatures, it was observed that the year 2017 presented the highest values in all the seasons of the year when compared to the same periods of the year 1993. It was possible to identify seven heat islands in the study area, and these are located in the class od urbanization and represented parking areas and rusted metal roofs of industrial pavilions. The temperatures in the heat islands varied from 40.26ºC to 42.47ºC, while the cooler areas, said islands of freshness, presented temperatures between 27.16ºC and 32.01ºC. the islands of freshness are represented by parks, forest areas and artificial water reservoirs. In these places, the temperature difference of the island of freshness to its surroundings reached 8.6ºC, case of the Dam Dal'Bó and the urbanized areas in its proximities. Note the importance of green areas as thermal refuges in densely urbanized environments. Public policies that value the creation of green spaces in urban centers promote, besides leisure spaces, a greater sense of comfort, especially on high temperature days (sic).