Name: | Description: | Size: | Format: | |
---|---|---|---|---|
8.51 MB | Adobe PDF |
Authors
Advisor(s)
Abstract(s)
Atualmente, a mitigação da ilha urbana de calor (IUC) é uma das grandes para a melhoria das condições de habitabilidade da população urbana. No presente trabalho pretendeu-se a determinação do potencial de arrefecimento dos espaços verdes em Lisboa, quantificando o volume de vegetação necessário para a redução de 1ºC na temperatura do ar. Para tal, foram selecionadas algumas áreas amostra: um jardim de média dimensão (Jardim da Fundação Calouste Gulbenkian), um jardim de pequena dimensão (Jardim Fernando Pessa) e duas ruas, uma com vegetação (Avenida Defensores de Chaves) e outra sem vegetação (Rua Actor Isidoro). Em todos os espaços foram recolhidos dados climáticos (instalação de redes meteorológicas urbanas e medições itinerantes) e, posteriormente, interpolaram-se as temperaturas no interior e no exterior de um jardim, de modo a caraterizar o comportamento térmico destes espaços verdes e a sua influência na área construída envolvente. Ao mesmo tempo, estimou-se a biomassa da cidade de Lisboa, a partir de modelos de deteção remota que recorreram ao índice de vegetação NDVI. Com o volume de massa verde, estimou-se a densidade de vegetação que, juntamente com a interpolação das temperaturas, permitiu a construção de um modelo de regressão linear simples de estimação do potencial de arrefecimento dos espaços verdes.
Concluiu-se que todos os espaços verdes estudados conseguiram, em algum momento, arrefecer o ambiente térmico envolvente. No entanto, a intensidade das ilhas de frescura (PCI – Park Cool Island) e as distâncias máximas de arrefecimento registaram grande variabilidade espacial e temporal. No Jardim da Gulbenkian registou-se uma intensidade média da PCI de 2,2ºC, em dias com nebulosidade moderada a forte e uma grande variabilidade em termos de velocidade média do vento. O Jardim Fernando Pessa esteve quase sempre mais quente que a sua área envolvente. Os fatores que poderão explicar estas diferenças prendem-se com a dimensão dos espaços verdes e a densidade e o tipo de vegetação presente, tendo-se constatado que o efeito de arrefecimento de jardins compostos maioritariamente por espécies herbáceas como a relva é muito reduzido ou nulo. Quanto às ruas analisadas, concluiu-se que a rua arborizada esteve, em média, 1ºC mais fresca que a rua sem vegetação, tendo as diferenças máximas atingido 3,7ºC.
A partir do modelo de regressão linear simples (temperatura do ar vs densidade da vegetação), concluiu-se que para a redução de 0,02ºC na diferença da temperatura entre um ponto de medição e um ponto fixo é necessário um incremento na vegetação de 1m2 (no plano).
Em suma, a metodologia utilizada neste estudo é um ponto de partida para a estimação do potencial de arrefecimento de toda a massa verde da cidade de Lisboa, sendo necessário prosseguir esta investigação estudando um maior número de jardins de Lisboa.
Nowadays, urban heat island’s mitigation is an important goal to improve health and comfort conditions of urban population. The purpose of this research is to evaluate the cooling potential of Lisbon’s green spaces, quantifying the volume of vegetation needed to reduce 1ºC in air temperature. Therefore, several green spaces were chosen as samples: a medium size green space (Jardim da Fundação Calouste Gulbenkian), a small size green space (Jardim Fernando Pessa) and two streets, one with vegetation (Avenida Defensores de Chaves) and one without vegetation (Rua Actor Isidoro). In all green spaces climatic data were collected (installation of urban meteorological stations and mobile measurements in predefined transects) and air temperature was interpolated in Jardim da Gulbenkian to characterize the thermal behavior of green spaces and its influence in the surrounding building area. Furthermore, the city’s biomass was estimated through several remote sensing models using NDVI. From this, the density of vegetation in Jardim da Gulbenkian was calculated. This output and the interpolated temperatures were used to develop a linear regression model to estimate the influence of vegetation on air temperature and the cooling potential of green spaces in the city. The main results indicate that all green spaces analyzed, at some moment, reduced air temperatures in their surroundings. However, the intensity of park cool islands (PCI) registered high temporal and spatial variability. In Jardim da Gulbenkian, the medium PCI recorded was 2,2ºC in days with moderate to high nebulosity and high variability of winds. Jardim Fernando garden was often hotter than surroundings. These differences may be explained by the dimension of green spaces and the type and area occupied by vegetation, since the cooling effect of green spaces covered mostly by grass is often small or absent. Regarding the two streets analyzed, Avenida Defensores de Chaves was, in average, 1ºC cooler than Rua Actor Isidoro, and maximum differences reached 3,7ºC. Considering the linear regression model built with air temperature and density of vegetation (predictive variable), it was concluded that, in order to reduce 0,02ºC in difference of air temperature between one measure point and a fixed station the area occupied by vegetation must be increased in 1m2 (planar measure). The methodology applied in this study may be considered as a base to estimate the cooling potential of all green spaces in Lisbon. Further research with a great number of green spaces is needed in the future in order to better quantify this effect.
Nowadays, urban heat island’s mitigation is an important goal to improve health and comfort conditions of urban population. The purpose of this research is to evaluate the cooling potential of Lisbon’s green spaces, quantifying the volume of vegetation needed to reduce 1ºC in air temperature. Therefore, several green spaces were chosen as samples: a medium size green space (Jardim da Fundação Calouste Gulbenkian), a small size green space (Jardim Fernando Pessa) and two streets, one with vegetation (Avenida Defensores de Chaves) and one without vegetation (Rua Actor Isidoro). In all green spaces climatic data were collected (installation of urban meteorological stations and mobile measurements in predefined transects) and air temperature was interpolated in Jardim da Gulbenkian to characterize the thermal behavior of green spaces and its influence in the surrounding building area. Furthermore, the city’s biomass was estimated through several remote sensing models using NDVI. From this, the density of vegetation in Jardim da Gulbenkian was calculated. This output and the interpolated temperatures were used to develop a linear regression model to estimate the influence of vegetation on air temperature and the cooling potential of green spaces in the city. The main results indicate that all green spaces analyzed, at some moment, reduced air temperatures in their surroundings. However, the intensity of park cool islands (PCI) registered high temporal and spatial variability. In Jardim da Gulbenkian, the medium PCI recorded was 2,2ºC in days with moderate to high nebulosity and high variability of winds. Jardim Fernando garden was often hotter than surroundings. These differences may be explained by the dimension of green spaces and the type and area occupied by vegetation, since the cooling effect of green spaces covered mostly by grass is often small or absent. Regarding the two streets analyzed, Avenida Defensores de Chaves was, in average, 1ºC cooler than Rua Actor Isidoro, and maximum differences reached 3,7ºC. Considering the linear regression model built with air temperature and density of vegetation (predictive variable), it was concluded that, in order to reduce 0,02ºC in difference of air temperature between one measure point and a fixed station the area occupied by vegetation must be increased in 1m2 (planar measure). The methodology applied in this study may be considered as a base to estimate the cooling potential of all green spaces in Lisbon. Further research with a great number of green spaces is needed in the future in order to better quantify this effect.
Description
Keywords
Espaços verdes biomassa PCI (Park Cool Island) temperatura do ar efeito de arrefecimento