Estudo de ilhas de frescor urbano em Porto Alegre - RS

Past studies developed in the Porto Alegre City and the State of Rio Grande do Sul of southern Brazil suggests that deforestation and urban developments (i.e. pavements, buildings, roads) interfere with the thermal quality of its urban spaces. The urban heat island is already recognized as phenomenon occurring in large cities. In this study we obtain estimates and evaluate surface temperature (TS) in urban parks and surroundings inside the Porto Alegre, using remote sensing data and land-use mapping. The surface temperatures were obtained by processing the thermal band of Landsat 7 ETM +, using a simplified energy balance model that accounts for atmospheric correction and terrestrial surface emissivity. Analysis of temperature differences in urban parks (and around) was performed for winter and summer seasons. It was observed that the temperature tends to increase with the distance from the parks, towards more urbanized areas. The temperature differences between the coldest points (inside) and warmer (park surrounding) was varied between 3.8 and 5.6°C in the winter; and from 6.2 to 8.6 °C in the summer. The radius of influence of each park in the TS values was estimated at between 50 and 200m from the edge, although it depends on particular characteristics of each park.