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- Application of climatic guidelines to urban planning: the example of Lisbon (Portugal)Publication . Alcoforado, Maria Joao; Andrade, Henrique; Lopes, António; Vasconcelos, JoãoIn order to contribute to the sustainability of the urban environment, knowledge about the urban climate should be translated into climatic guidelines for planning. However, there are hardly any studies on applied urban climatology in areas with a Mediterranean type of climate. The study presented in this paper has several aims: to identify the climatic needs in a coastal city with Mediterranean climate; to describe the methodology, which can be adapted in order to be used in other cities; to discuss some of the problems that arise when applying climatic knowledge to urban planning, including the selection of the adequate scale of analysis, the required data and tools, the selection of the planning priorities, and the need to develop a shared language among planners and climatologists; and last to contribute to furthering the debate on the advantages of including climatic guidelines in Master Plans of urban municipalities in a systematic way. Lisbon’s case study is presented. As planners need spatialized guidelines, the mapping of Lisbon’s physical features was carried out using a Geographical Information System. Based on a Digital Terrain Model and on data of urban roughness a “ventilation map” was produced. A “building-density” map was also prepared based on the analysis of a Landsat image and field work. By crosstabulating these two layers, a final map depicting Lisbon’s “homogeneous climatic-response units” was prepared. Finally, a series of climatic guidelines for planning were put forth for the different units.
- 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.
- Thermal preference and pleasantness of a students’ population in a coastal urban area during summerPublication . Silva, Tiago; Lopes, António; Vasconcelos, João; Morgado, PauloIn thermal comfort research, two main domains are identified: objective and subjective. This study focusses on the latter, examining various aspects of preference, sensation, and pleasantness. It also clearly distinguishes each concept and sets the groundwork for their standardised use in urban planning and urban climate studies. Additionally, this study emphasises the often-overlooked geographical perspective, aiming to address previous gaps in this research area. Environmental conditions were found to be the main determinants influencing pedestrians' thermal sensation, preference, and pleasure. Key factors include air temperature, solar radiation, and wind speed, which exhibit strong correlations with pleasure responses. Additionally, urban density, clothing type and colour, shading, sex, and weather type significantly impact thermal sensation and reported pleasantness. It was observed that people who overdressed for the season, wore dark or warmer clothes, experienced air temperature and solar radiation more intensely. Similarly, those in high-density urban areas, without shade, or when weak continental wind conditions were observed, reported stronger thermal sensations. Women generally sensed air temperature and solar radiation as more intense compared to men. These factors influence thermal pleasantness, varying in importance, spatial distribution, and statistical relationship. Higher wind speeds, particularly from an Atlantic direction, were found to enhance thermal pleasantness by balancing conditions and reducing thermal sensation votes for air temperature and solar radiation. Green areas also increased thermal pleasantness by lowering air temperature and solar radiation sensations and promoting a sense of happiness among pedestrians.
- A micro-scale look into pedestrian thermophysiological comfort in an urban environmentPublication . Silva, Tiago; Lopes, António; Vasconcelos, JoãoDiferent spatial scales enable the analysis of thermophysiological conditions of pedestrians in an urban environment. A higher resolution hotspot analysis was conceived using GIS technology in some areas of Lisbon with diferent morphological conditions. Eleven hotspots were found across six study areas, located in high to moderate urban density conditions and in diferent types of urban spaces. So, six hotspots were found in avenues (high urban density conditions), three in streets, and two in general open spaces (moderate urban density conditions). These spaces are characterized by being busy areas with high anthropogenic infuence, with high-absorbing and refective materials, and with very poor green infrastructure. Environmental conditions, namely, radiation, mean radiant temperature, and air temperature, were the main cause of hotspot existence, and the main propellers for UTCI intensifcation. The urban density variable was also found to be important, especially in avenues and open spaces. In these areas, the adjusted component for environmental and urban density conditions can increase 0.60 to 1.35 °C in open spaces and 0.30 to 0.60 °C in avenues, each time there is a one-unit increase in the component. Trees, either in the street or in parks, have generally been found to decrease the UTCI.
- Thermal stress and comfort assessment in urban areas using Copernicus Climate Change Service Era 5 reanalysis and collected microclimatic dataPublication . Silva, Tiago; Lopes, António; Vasconcelos, João; Chokhachian, Ata; Wagenfeld, Malte; Santucci, DanieleIn this initial study of a research project, this paper seeks to understand the thermal conditions in the cities of Lisbon and Munich, specifcally focusing on Urban Heat Island intensity and on thermal comfort using the Universal Thermal Climate Index modeling data at the Local Climate Zone scale. Based on these datasets, Munich has exhibited more unfavourable thermal conditions than Lisbon. In terms of UHII, both cities have shown that low, medium, and high rise compact urban areas and bare rock or paved areas have the highest values, while sparsely built areas have the lowest. These results difer from the UTCI, which indicates that in Lisbon and Munich, these sparsely built areas as well as areas with low plants and vegetation are the most uncomfortable. In Munich, the population was exposed to very strong heat stress, while Lisbon experienced strong heat stress conditions. Conversely, low, medium, and high rise compact urban areas and densely wooded areas in Munich, and scattered trees areas and large low-rise urban areas in Lisbon, have demonstrated the lowest monthly mean and average maximum values. These results will be further explored in future studies in the city of Lisbon and crosschecked with data obtained from roving missions. This will enable a more detailed temporal and local analysis.
- A micro-scale look into pedestrian thermophysiological comfort in an urban environmentPublication . Silva, Tiago; Lopes, António; Vasconcelos, JoãoDifferent spatial scales enable the analysis of thermophysiological conditions of pedestrians in an urban environment. A higher resolution hotspot analysis was conceived using GIS technology in some areas of Lisbon with different morphological conditions. Eleven hotspots were found across six study areas, located in high to moderate urban density conditions and in different types of urban spaces. So, six hotspots were found in avenues (high urban density conditions), three in streets, and two in general open spaces (moderate urban density conditions). These spaces are characterized by being busy areas with high anthropogenic influence, with high-absorbing and reflective materials, and with very poor green infrastructure. Environmental conditions, namely, radiation, mean radiant temperature, and air temperature, were the main cause of hotspot existence, and the main propellers for UTCI intensification. The urban density variable was also found to be important, especially in avenues and open spaces. In these areas, the adjusted component for environmental and urban density conditions can increase 0.60 to 1.35 °C in open spaces and 0.30 to 0.60 °C in avenues, each time there is a one-unit increase in the component. Trees, either in the street or in parks, have generally been found to decrease the UTCI.
- Modeling the influence of summer sea and estuarine breezes on heat stress in Lisbon (Portugal) using GRAMM-SCIPublication . Reis, Cláudia; Oettl, Dietmar; Lopes, António; Nouri, A. Santos; Vasconcelos, JoãoIn this study, the influence of the Tagus river and Atlantic Ocean breezes in a Mediterranean city (Lisbon) on outdoor thermal comfort was analyzed during the thermal summer days. Hourly wind fields were modeled using the GRAMM-SCI software, initialized with ERA5 reanalysis data. The Universal Thermal Climate Index (UTCI) was calculated for 80 weather stations across the city. Additionally, the UTCI anomalies (ΔUTCI) relative to a reference site (the airport weather station) were calculated during breeze and non-breeze events (typically N/NW winds). Results showed that sea breezes can reduce UTCI levels by up to 2,2◦ C during typical breeze days and up to 5,1◦ C during heatwave breeze events. The effect of these breezes on heat stress conditions is felt up to 4 km from the Tagus river, but especially on the areas up to 500 m. However, in 50 % of the cases where no thermal stress was recorded at the airport during breeze events, Lisbon’s riverfront can be more uncomfortable (moderate heat stress) than the northern part of the city (from 2 to 8 km). Additionally, cooling effect of the breezes is only significant enough to cause a transition to a more comfortable UTCI class (especially from very strong to strong heat stress and from strong to moderate heat stress) during heatwaves (strong to very strong heat stress) and on areas up to 1,5 km from the estuary. The promotion of wind corridors is, therefore, crucial to insuring the progression of sea breezes in urban areas and to reduce heat stress.
- Unveiling the Thermo‐Hygrometric Influence of Summer Sea and Estuarine Breezes (SEBs) in Lisbon (Portugal)Publication . Reis, Cláudia; Lopes, António; Nouri, A. Santos; Vasconcelos, JoãoLocal wind, such as sea breezes, play a crucial role in cooling coastal cities. This study presents new insights about the thermo-hygrometric influence of the Tagus and Atlantic Ocean breezes(sea and estuarine breezes [SEBs]) in Lisbon’s urban climate (Portugal). SEB events were identified in the summer of 2022 according to a wind rotation criterion: the interruption of prevailing North and Northwest (Nortada) winds during the morning, the wind shift to Northeast/East/Southeast and, sometimes, to further South/Southwest/West (rotation between 22.6° and 292.5°) and the return of the regional flow at late afternoon. Additionally, air temperature and absolute humidity anomalies (ΔT/Haurb) were calculated according to the distance to the riverfront area. Results show that SEB occurred on 37 (31%) out of 120 days, mainly in July (43%) and August (32%), between, on average, 10:00 AM and 4:00 PM, and average wind speeds of 3.4 m/s. According to the daily thermo-hygrometric cycle, the areas up to 4 km of the Tagus estuary were, on average, cooler than northern Lisbon during SEB events, especially the areas up to 500 m (average ΔTurb reached −1.7°C). Additionally, there was a significant increase in the moisture content during SEB hours across the city but especially close to the riverfront area: the areas up to 500 m registered, on average, ΔHaurb of 4.2 g/m3 on SEB events (12:00 PM) against 2.1 g/m3 during typical Nortada days. This research is a starting point for a future delimitation and preservation of SEB penetration zones in Lisbon to address outdoor thermal discomfort during summer.
- Climate walking and linear mixed model statistics for the seasonal outdoor thermophysiological comfort assessment in LisbonPublication . Silva, Tiago; Reis, Cláudia; Braz, Diogo; Vasconcelos, João; Lopes, AntónioTo measure urban outdoor pedestrian thermophysiological comfort mobile roving missions were conducted in all seasons of the year during the day and at night. Six routes were chosen, representing areas of the city with varying urban morphological layouts. The thermal comfort conditions were analysed using the Local Climate Zone spatial scale. This enabled the identification of typologies of areas where pedestrians might feel (un)comfortable. To achieve the proposed objectives, quantitative and qualitative analysis were run, namely a Linear Mixed-Effect Model. This model was useful to understand the thermal behaviour of the roved areas by comparison to a reference area. The city was found to be generally cooler, except at night when it can have a 44% increased UTCI. Most collected values throughout the year had ‘no thermal stress’, except in the summer when ‘moderate’ and ‘strong heat stress’ was predominant. Compact and large low rise urban areas were found to be the most uncomfortable. Significant amplitudes were found in some LCZs, reaching as high as 7 ◦C in some scenarios. Sparsely wooded areas exhibited higher values in all seasons and at night, except in the summer. This showed that for a local heat stress analysis a higher resolution scale is needed.