Loading...
9 results
Search Results
Now showing 1 - 9 of 9
- Surface radiation balance of urban materials and their impact on air temperature of an urban canyon in Lisbon, PortugalPublication . Matias, Márcia; Lopes, AntónioUrban climate results from the modifications caused by the characteristics of cities, which modifies the regional climatic conditions of a city. When urban areas are warmer than the surrounding areas, the urban heat island (UHI) phenomenon occurs. Being a major phenomenon and a global topic of interest for all affected cities, there are already numerous studies that address this subject. However, most studies are only focused on the macro and mesoscales. This study looks at the micrometeorological scale in a neighborhood of Lisbon (Telheiras). Having as a main objective to evaluate how the radiation balance of urban materials influences air temperature in an urban canyon, thermal images of different urban materials were obtained using infrared thermography, a technique that allowed understanding how the temperatures registered in the facades and other urban surfaces can affect the air temperature of the urban canyon. The components of the radiation budget were obtained by using a pyranometer and a pyrgeometer. Moreover, a microclimatic network to monitor air temperature and relative humidity was installed in the study area. The results show that, when the streets are less exposed to the prevailing wind direction in Lisbon (north and northwest), air temperatures are slightly higher than those found in opposite conditions. Both the temperature and the radiative balance of the facades and other surfaces (asphalt, light Portuguese sidewalk, and tile floor) respond directly to incident solar radiation. As expected, it was found that south facades have the highest temperatures of the four exposures under study (>4 ◦C when compared to the opposite facade), and the highest radiative balance was always registered on asphalt when compared to the sidewalk (at 9:00 a.m. + 30 W·m−2 , at 1:00 p.m. + 149 W·m−2 , and at 7:00 p.m. + 66 W·m−2 ).
- Heat stress mitigation by exploring UTCI hotspots and enhancing thermal comfort through street treesPublication . Silva, Tiago; Matias, Márcia; Girotti, Carolina; Vasconcelos, João; Lopes, AntónioHeat stress mitigation actions must be carefully planned in order to achieve efective outcomes. By integrating urban planning guidelines with urban climate knowledge, substantial benefts can be achieved for the community. In Lisbon, the study area, urban planning guidelines are strict in relation to the tree species which should be used for planting. This study examined these species environmental contributions to the community, especially in regard to heat stress mitigation in two urban canyons previously found as UTCI hotspots. For this, microclimatic Envi-met simulations were run which allowed recalculation of the UTCI hotspot analysis and to assess individual species contribution to possible mitigation eforts. Results demonstrated the ability of these trees to lower air temperature and the Universal Thermal Climate Index (UTCI). By reducing UTCI temperatures between 3.19 °C and 6.27 °C on a hot summer’s day, these trees were also able to transform an identifed UTCI hotspot into a coldspot. From the studied species, Pyrus calleryana was found to be the most efective species for mitigating thermal stress, although all three species performed well. Regarding community services, according to the iTree tool, Cercis siliquastrum had the greatest overall impact. These results give to the municipal urban planning which tree species should be prioritized in terms of climate action, as well as a methodological framework to assess at local scale which areas should be intervened.
- Method for assessing volumetric solar potential within urban street canyonsPublication . Santos, Teresa; Matias, Márcia; Rocha, Jorge; Lobato, KillianWhile rooftops have been extensively studied for their photovoltaic (PV) potential, the volumetric space between buildings remains largely unexplored. This study introduces a replicable framework to quantify solar radiation within this unoccupied urban volume. The methodology leverages widely available city-scale datasets (e.g., LIDAR data, elevation contours, and building footprints) and accessible software to generate virtual surfaces at incremental heights between buildings. These surfaces serve as the basis for calculating solar insolation at 30-min intervals. The approach is demonstrated using neighbourhoods with differing urban morphologies to showcase its applicability across various contexts. This framework produces detailed insolation maps, revealing how volumetric solar radiation varies with urban form and time of year. The use of city-scale datasets makes this approach particularly suited for planning at the urban scale, enabling urban planners to identify optimal locations for PV installations, enhance urban thermal comfort, and improve street luminosity. The primary contribution of this study lies in the accessibility and generalizability of the methodology, which can be applied to support urban design decisions where solar insolation is a critical factor. By addressing the underexplored volumetric solar potential, this study provides actionable tools for advancing urban sustainability.
- The Climate of My Neighborhood: Households’ Willingness to Adapt to Urban Climate ChangePublication . Matias, Márcia; Lopes, Sara; Lopes, AntónioRegarding the predisposition of individuals to change when confronted with future climate scenarios, it is necessary to understand the perception of the groups under analysis and how to engage with society to collectively act toward climate change mitigation. A question remains to be answered: how to ensure that people engage, participate, and gain awareness of the undergoing problem that urban climate change poses for the future of cities’ management? This research intends to contribute to solving this question by raising another question: “How willing are residents of the Alvalade neighborhood (Lisbon) to change their behavior and way of life when faced with climate change scenarios?” We present a methodology using microclimatic modeling with ENVI-met and questionnaires for the resident community. The present and future local climate scenarios (representing a present hot day versus the extreme IPCC RCP 8.5 scenario) were presented to a set of residents. These figures show the projected UTCI (Universal Thermal Climate Index) in a dramatic but accurate aggravated way. The inquiries allowed us to conclude that people are more aware of local climate change and health risks from extremely hot summer weather, but they continue to resist adopting behavior change for adaptation, although most of them declared this could be important to tackle climate change. The second conclusion is that people think that local authorities should be more active than themselves and will have greater responsibility for climate change adaptation and interventions. In times of climate crisis, the participation of the resident community can be an important help in decision making and finding measures to mitigate adverse climate effects in urban environments.
- Climate walking: A comparison study of mobile weather stations and their relevance for urban planning, design, human health and well-beingPublication . Silva, Tiago; Ramusga, R.; Matias, Márcia; Amaro, J.; Bonifácio, Ana; Reis, Cláudia; Chokhachian, A.; Lopes, G.; Almeida, A.; Frazão, J.; Vasconcelos, J.; Lopes, António; Morgado, PauloMicroclimate conditions affect the outdoor urban way of life for humans. These conditions directly impact people’s health and well-being, such as access to medical care or a healthy lifestyle. Human thermal comfort is paramount for people’s health, both physical and mental. In this paper, the study compares two microclimate mobile weather stations (MWS) based on a set of users’-based assessment criteria (usability, user-friendliness, sensors) and thermal comfort (UTCI) results accuracy. The comparison was carried out through continuous mobile transect measurements lasting an hour and a half, conducted on two summer days in Lisbon across distinct urban morphological settings. This research was developed to assist future researchers in urban climatology with the design of microscale studies, particularly in relation to equipment selection, performance assessment, and methodological procedures. In terms of performance, we found the RMSE to be 1.3 ◦C for air temperature, 1.6 % for relative humidity, 1.3 m/s for wind speed, and 8.4 W/m2 for solar radiation for MWS 1, and 1.5 ◦C for air temperature, 2.9 % for relative humidity, 1.5 m/s for wind speed, and 11.6 W/m2 for radiation for MWS 2. Both MWS units exhibited a consistent performance, however, MWS 1 demonstrated greater overall accuracy, particularly in the measurement of air temperature, relative humidity, and wind speed. Differences were also observed between the sensors of MWS 1 and MWS 2, as well as in the MWS usability, factors which may be significant depending on the users’ objectives and available resources. Despite this, both MWS units were deemed suitable for deployment in urban environments, with MWS 2 offering a more intuitive user experience. The findings of this study are particularly relevant for those beginning mobile meteorological measurements, as well as for researchers aiming to address urban heat stress and enhance public well-being and thermal comfort through their work. However, the study is limited by its short duration and geographic scope, and further research is needed to expand its applicability to diverse urban settings.
- O balanço radiativo de um conjunto de edifícios em Telheiras com recurso a termografia infravermelhaPublication . Matias, Márcia Alexandra Neves; Lopes, António Manuel SaraivaO presente trabalho tem como objetivos calcular o balanço radiativo de um conjunto de fachadas em Telheiras (Lisboa), obter imagens térmicas das fachadas dos edifícios em estudo, através da termografia infravermelha, compreender de que forma as temperaturas registadas nas fachadas e superfícies da área de estudo afetam as temperaturas do ar registadas no canyon urbano, perceber de que modo os valores do balanço radiativo registados nas fachadas e diferentes superfícies influenciam as temperaturas do ar e comparar os valores obtidos através do modelo micrometeorológico ENVI-met com as observações realizadas em campo. Para atingir estes objetivos foram calculadas as temperaturas de superfície, através de imagens de satélite, procedeu-se à instalação de uma rede microclimática na área de estudo, para a monitorização da temperatura e humidade relativa do ar, e com recurso a uma câmara térmica FLIR, foram recolhidas as temperaturas de superfície das fachadas e respetivos materiais. Foi igualmente calculado o balanço radiativo destas superfícies e das fachadas dos diferentes edifícios com recurso a um piranómetro e a um pirgeómetro. Os valores observados foram comparados com os resultados obtidos na modelação tridimensional, através do cálculo das diferenças entre os valores observados em campo e os estimados pelo modelo. Os resultados obtidos mostram que os locais mais expostos à direção predominante do vento (norte e noroeste) apresentam temperaturas do ar relativamente mais baixas do que os que se encontram em abrigo (ruas perpendiculares a essa direção). Tanto a temperatura como o balanço radiativo das fachadas e outras superfícies (asfalto, calçada portuguesa de cor clara e pavimento em azulejo) respondem diretamente à radiação solar incidente. São as fachadas expostas a sul onde se verificam sempre as temperaturas mais elevadas das quatro exposições em estudo. As temperaturas e o balanço radiativo mais elevado são quase sempre registados no asfalto. O modelo ENVI-met, utilizado para a modelação tridimensional de diferentes variáveis recolhidas em campo conseguiu, de certa forma, modelar corretamente a variação diurna da temperatura do ar no canyon urbano. Relativamente à temperatura das fachadas e ao balanço radiativo destas superfícies, o modelo 3D estima valores superiores aos observados em campo, maioritariamente, quando as fachadas se encontram a receber radiação solar. Este estudo tem um cariz totalmente inovador em Portugal, sendo necessário prosseguir a investigação noutras áreas de estudo e períodos do ano, de modo a encontrar soluções de materiais que possam ajudar a mitigar o efeito de ilha urbana de calor de Lisboa.
- Modelação do crime em Lisboa no espaço e no tempoPublication . Rocha, Jorge; Matias, Márcia; Almeida, Ana RitaO crime é um evento dinâmico, distribuído segundo tendências espaciotemporais. Neste artigo implementa-se um processo de análise criminal para a cidade de Lisboa através do mapeamento e análise de ocorrências geolocalizadas. Através de Sistemas de Informação Geográfica (SIG) procura-se otimizar a identificação de padrões espaciotemporais, analisar o fenómeno criminal, identificar zonas específicas e promover a adoção de políticas preventiva mais eficazes. Para esse efeito, foi efetuada a geocodificação das ocorrências registadas no espaço público entre janeiro de 2014 e dezembro de 2017. Dentro do variável espaço, verificam-se quais os diferentes espaços onde ocorrem os mesmos tipos de crime e correlaciona-los com as condições físicas e sociais. Relativamente à variável tempo, pretende-se entender através dos dados disponíveis, a existência de padrões temporais para os diferentes tipos de crime. No intuito de alcançar o objetivo foram utilizados hotspots, data mining, método de Kernel, Índice de Moran, Distância-Custo e Regressão Bayesiana. Os dados analisados permitem observar a densidade criminal segundo os tipos de crime, e propor sugestões a nível da gestão de recursos das esquadras, calculando o custo do percurso esquadra-ocorrência, considerando a sua densidade criminal e permitindo identificar as variáveis ou padrões relevantes para a prevenção do crime.
- LCZ thermal and exoatmospheric albedo assessment using Landsat 8 land surface temperature and reflectance dataset: case study of LisbonPublication . Matias, Márcia; Lopes, AntónioThis study investigates microclimate changes induced by urbanization, with a focus on the Urban Heat Island (UHI) phenomenon and the crucial role of Land Surface Temperature (LST). Using the Landsat 8 Land Surface Temperature and Reflectance dataset obtained from the USGS Earth Explorer platform, the research evaluates LST and exoatmospheric albedo characteristics within Lisbon's Metropolitan Area across a defined set of thermal periods from 2015 to 2020. Among the findings, the Bare Soil or Sand LCZ consistently exhibits heightened LST values, while the Large Low Rise urban LCZ consistently records the highest temperatures, exceeding 54 °C and 55 °C in spring and summer and 43.8 °C and 37.8 °C in autumn and winter, respectively. These insights, derived from a meticulous examination of the Landsat 8 dataset and advanced processing methods, bear critical implications for climate change adaptation strategies, providing valuable insights to mitigate the adverse effects of the Urban Heat Island and foster sustainable urban development practices.
- Uso inteligente do potencial solar em espaços públicos da cidade lisboaPublication . Matias, Márcia; Lobato, Killian; Santos, Teresa; Rocha, JorgeA energia tem um papel central na nossa vida e sobretudo nas economias dos países. Nas últimas décadas tem-se assistido a um aumento do consumo de energia muito devido à contínua expansão urbana. Esse aumento de consumo tem originado um impacto negativo sobre o ambiente, levando a uma procura por soluções energéticas alternativas que visem o equilíbrio entre a viabilidade económica e o abastecimento energético sobretudo nas áreas urbanas, como o caso da energia solar. No entanto para que seja possível promover o uso da energia solar em ambiente urbano é necessário, em primeiro lugar, conhecer as características e a distribuição geográfica das melhores localizações para se implementar sistemas solares. Neste contexto, o presente trabalho tem como objetivo criar um modelo solar que permita caracterizar, estimar e quantificar o potencial solar dos espaços públicos a diferentes altitudes acima do nível do solo. Este modelo foi testado em 4 áreas do concelho de Lisboa, recorrendo aos Sistemas de Informação Geográfica. Estas áreas prefiguram diferentes morfologias urbanas, capazes de influenciar de forma diferenciada a radiação incidente sobre a superfície. É dada ainda especial importância aos espaços públicos existentes, sejam de uso livre ou não, como potenciais espaços de implementação de estruturas de aproveitamento de energia solar descentralizadas; considera-se que estes representam um ativo muito importante e ainda por explorar. Pretende-se assim elaborar um modelo solar bem parametrizado, para futuros estudos de radiação solar fornecendo uma informação detalhada sobre a disponibilidade dos recursos energéticos em espaços públicos.