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The present study is based on remote sensing techniques focusing on Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI) to investigate their influence on land use and land cover dynamics, and the assessment of the Urban Heat Island (UHI) effect in Delhi, India. The objective of this study is to calculate LST, NDVI, and UHI values to understand the changes in LULC patterns, urbanization, and temperature increase within the city. Unlike previous studies conducted with Landsat-8, the present study employs Landsat-9 data, ensuring a higher level of authenticity in the results. Landsat-9, equipped with state-of-the-art sensors and instrumentation, provides superior data quality, enhanced image resolution, and advanced capabilities for precise monitoring and analysis. The methodology encompasses six steps for LST retrieval, enabling the calculation of UHI values and intensity. Ground data from 32 meteorological stations validate the LST results. Pearson correlation coefficients between LST and NDVI exhibit correlations ranging from −0.58 to −0.68 for three dates. On Dec 8, 2023, there is a weak negative correlation of −0.004. The analysis of changing land cover with variation in NDVI and LST unveils a diverse landscape, primarily characterised by green cover (47.34%), followed by built-up area (44.57%), barren land (7.57%), and water (0.52%). The study identifies the minimum value of UHI intensity for Delhi to be 8.13 °C on 26-Feb 2023 and the maximum value of UHI was estimated 10.29 °C on 2-June 2023. The study of Urban Heat Island (UHI) patterns revealed distinctive seasonal trends. The urban areas exhibited relatively cooler temperatures compared to surrounding rural regions on Dec 8, 2023. The conclusion drawn from this comprehensive analysis is that rapid urbanization in Delhi has significantly contributed to the increase in LST and UHI values. This rise can largely be attributed to the extensive use of concrete in construction activities, which exacerbates the UHI effect. Moreover, this analysis signifies the dynamic nature of UHI and emphasizes the urgency for strategic urban planning and climate-sensitive design approaches. Implementing such measures can create more sustainable and resilient urban environments. • Landsat-9 provides superior data quality and enhanced image resolution for precise monitoring and analysis. • The analysis of changing land cover with variation in NDVI and LST unveils a diverse landscape characterized by green cover. • The study identifies the min and max values of UHI for Delhi to be 8.13 °C on 26-Feb 2023 and 10.29 °C on 2-June 2023. • The study of Urban Heat Island (UHI) patterns revealed distinctive seasonal trends. [ABSTRACT FROM AUTHOR]

• Different urban factors were identified to affect UHI during different seasons and times of day. • Spatial extents of the effect of various urban variables on UHI are presented. • Relationships between urban variables and UHI were strongly influenced by humidity. This study utilizes year-round temperature data observed in 15 cities around the United States (U.S.) to investigate the relationships between UHI and urban design attributes, and answer the following questions: (1) Whether and to what extent these relationships vary with the diurnal cycle and across seasons?, (2) What is the spatial extent within which UHI is affected by different urban variables?, and (3) Which climatic factors determine the correlations between UHI and urban variables? Our analysis revealed that while surface reflectance, vegetation and building height are more influential on winter UHI, the effect of anthropogenic heat and building density is independent of the season. Also, tree canopy cover, impervious area and built-up area were more dominant on nighttime UHI, and albedo, surface reflectance, vegetation and building height had stronger influence on daytime UHI. With regards to the spatial extent, while the effect of 3D urban variables and imperviousness was prominent in the immediate vicinity (250 m–1 km), the effect of vegetation, surface reflectance and anthropogenic factors extend to a larger surrounding area (4 km–8 km). Lastly, the relationships between UHI and urban variables were noted to be strongly driven by humidity in each location. [ABSTRACT FROM AUTHOR]

• Diurnal and seasonal pattern of UHI is evaluated using WRF with LCZ in Rasht, Iran. • The maximum (3.4 °C) and minimum (0.6 °C) UHI is recorded in summer over 2017-2019. • Daytime rainfall duration has different effects on diurnal UHI in cold and hot seasons. • An increase in midday cloudiness reduces (enhances) the nocturnal (daytime) UHI. • UHI of dry summer nights with low cloud cover is proportional to U−0.33. • Long-term SUHI has an increasing trend in hot seasons over the last two decades. Due to the complicated and uncertain dynamics of the urban heat island (UHI) in humid subtropical areas, the diurnal, seasonal and long-term variations of the UHI were investigated in Rasht, Iran. Besides, the study utilizes the heat and moisture transfer concepts to analyze the impacts of daytime rainfall duration on UHI. Meteorological data at five virtual stations was acquired by verified Weather Research and Forecasting (WRF) model. Overall, the nighttime UHI peaks in summer (3.4 °C) and is lowest in fall (1.4 °C) over 2017–2019. Moreover, the maximum and minimum daytime UHI occurred in winter (1.2 °C) and summer (0.6 °C), respectively. In hot seasons, an increase in daytime precipitation duration initially leads to an increase in daytime UHI, followed by a subsequent decrease. Conversely, in cold seasons, daytime UHI shows a decreasing trend regardless of rain conditions. Additionally, extended daytime precipitation attenuates nocturnal UHI in hot seasons, while no significant influence is observed in cold seasons. An increase in midday cloud cover during hot seasons reduces the nighttime UHI. The nighttime UHI is inversely proportional to the third root of wind speed, in low cloudiness conditions of hot seasons. Furthermore, the Ladsat-5/7/8 imageries revealed an increasing trend in the surface UHI (SUHI) during hot seasons over the past two decades, while SUHI in cold seasons remains insignificant. The article reports the most influential parameters on daytime, nighttime and seasonal UHI and the best mitigation policies for the humid subtropical climate, particularly in hot seasons. [ABSTRACT FROM AUTHOR]

To gain the insight into the impacts of different urban thermal conditions on precipitation, a series of simulations that modified the surface sensible heat from building is performed during a thunderstorm passage over Beijing. The UHI intensity changed from 0.8 to 2.2 °C with the increase sensible heat. Results showed that: (i) Under weak UHI conditions (≤1.4 °C), it is the urban dynamical effect that played the dominant role. The surface flow was blocked by the urban rough surface, inducing updrafts around the central urban area (CUA) and downdraft over the CUA. As the thunderstorm passed, its convergence line broke over the CUA. The precipitation thus bifurcated; (ii) Under strong UHI conditions (≥1.8 °C), it is the urban thermal factor that played the dominant role, overshadowing the urban dynamical impacts which still existed. The intensified UHI led to a more organized UHI circulation, with stronger updrafts over the CUA. When the storm arrived, the pre-existing updraft and convergence was conducive to convection initiation and enhancement. The precipitation thus concentrated over CUA and strengthened. Employment of a cooling tower scheme improved the simulated precipitation. This study thus represents an initial attempt to differentiate urban thermal and dynamic impacts on thunderstorms. • Under weak UHI conditions, the urban building barrier effect plays the dominant role affecting precipitation. While the urban thermal factor is more prominent under strong UHI conditions. • The precipitation max gradually concentrates into the urban area with the increase in UHI. • The coupling of a cooling tower scheme improves the precipitation pattern simulation. [ABSTRACT FROM AUTHOR]

Water-retaining semi-flexible pavement (WRSFP) can effectively mitigate the urban heat island (UHI) effect by reducing the pavement temperature through water evaporation. To reduce environmental impacts and enhance the water retaining capacity and mechanical properties of WRSFP, this paper investigated the effect of proportion of water-retaining grout (WRG) on workability of fresh WRG, compressive strength, flexural strength, and water absorption of hardened WRG based on alkali-activated slag (AAS) system. The optimal proportion of WRG was recommended. The microstructure of the hardened WRG was observed with a scanning electron microscope (SEM), which allowed for a better characterization and understanding of the degree of hydration and mechanical properties of WRG. The WRSFP specimens (WRSFP-20%, WRSFP-25% and WRSFP-30%) with different porosities of porous asphalt mixture (PAM) were tested for moisture susceptibility, rutting resistance and low-temperature cracking resistance. WRSFP-25% had the best moisture resistance and rutting resistance, and the worst low-temperature cracking resistance. The maximum difference of upper surface temperature between WRSFP and stone mastic asphalt (SMA), which is commonly used in pavement, was 13.3 °C. The time to reach 60 °C on the upper surface of WRSFP was 3.4 times longer than that of SMA, which showed an excellent cooling effect of WRSFP. • Water-retaining semi-flexible pavement (WRSFP) was developed. • Proportion of grout based on alkali-activated slag was recommended. • The properties of WRSFP made from matrices with three porosities were evaluated. • The surface temperature of the WRSFP was up to 13.3 °C lower than that of the SMA. [ABSTRACT FROM AUTHOR]

Thermal environment within a typical street canyon can be represented by the heat exchange interactions between the microclimate and built-up urban fabric elements, consisting of walls, roofs and pavement surfaces. Morphology of these elements, material thermophysical and surface solar radiation characteristics under the prevalent weather conditions determine heat storage, convective as well as radiative heat exchanges within the street canyon. Predicting these heat transfer mechanisms using thermal model can facilitate assessing air temperature within the street canyon. Therefore, in this study, an easy-to-use resistance capacitance based thermal model is developed and verified using real-scale experimental measurements under the tropical climate of Singapore. Furthermore, the impact of increased solar reflectance of walls and the driveway surfaces (by application of cool coating) on the street canyon air temperature is predicted. Increasing the solar reflectance of wall from 0.5 to 0.8 and driveway from 0.2 to 0.7 can reduce the peak air temperature up to 1.70°C and daily mean air temperature up to 0.85°C as observed in this study. The results of the proposed cool coating thermal model can be used in early-stage design by the designers and planners for assessing the thermal impact of cool coating implementation on the street canyon surfaces under any weather conditions. • A simplified resistance and capacitance based cool coating thermal model is developed for urban canyons. • The proposed model is validated using real-scale experimental measurements. • Increasing the wall reflectance by 0.30 and driveway reflectance by 0.50 can reduce the maximum air temperature up to 1.7 °C. • The proposed thermal model can be used in early-stage design decisions. [ABSTRACT FROM AUTHOR]

Temperature in cities cores has realized always warmer than the surroundings, which is described as Urban Heat Island (UHI) phenomenon. Using of vegetation is one of the effective methods to combat this phenomenon. This study used urban parks (27 parks) located on three distance levels from the Melbourne city centre, which were choose by graduated size. Parks were heavily tested eight measuring time per day (six major and two minor) per month. Handheld measurement device used to measure Land Surface Temperature (LST) used to collect data during all transect points, which extended up 0.295–3 km beyond each park's perimeter. Study results presented that average maximums Park Cool Island (PCI) between 3 °C and 10 °C for all rings, however, parks close to the city centre showed higher PCI than the others during the first part of average maximums of Park Cooling Distance (PCD) up to 1100 m. Closest parks to the city (Ring 1) extended PCD to 3000 m, however, the other parks reached farther than 2000 m. Study concluded that all parks provided cooling benefits to the surrounding urban area. Urbanization was strongly effected on cooling magnitude (PCI) in the first cooling distance, which reached to 746 m. In the other words, parks decreased temperature in the built up areas started from the edge of parks to 746 m (Ring 1 > Ring 2 > Ring 3). [ABSTRACT FROM AUTHOR]

Numerous studies have showed that landscape composition and configuration can significantly affect land surface temperature (LST). Most of these studies focus on the horizontal dimension of landscape structure. Few studies, however, have explored the effects of vertical dimension of urban landscape. This study aims to fill this gap. We focused on the residential landscapes in the central area of Beijing, and quantified the relationships between the vertical structure of buildings and LST. We delineated the boundaries of residential neighborhoods based on high resolution imagery, which were latterly used as the unit of statistical analysis. Building height, and proportional cover of buildings and vegetation were also mapped from high resolution imagery, with aid of digital maps. LST was retrieved from thermal band of TM imagery. We used Pearson correlation, partial correlation and ordinary least squares(OLS) regressions to quantify the relationships between these variables and LST. We found: 1) Land surface temperature varied greatly among residential neighborhoods, ranging from 53.5 °C to 37.0 °C, with a mean of 44.2 °C and a standard deviation of 2.4 °C. High-rise residential neighborhoods had the lowest LST, and mean LST decreased from low-rise to high-rise residential neighborhoods. 2) Building height, building density and vegetation coverage were all significantly correlated with LST. Building height and vegetation coverage has significantly negative effects on LST, but building density had a significantly positive one. 3) Among these variables, building height had greater impact on LST than the other two variables. These results have important implications for urban design and management. • Mean LST decreased from low-rise to high-rise residential neighborhoods. • Building height has significantly negative effects on LST in residential neighborhoods. • Building height had greater impacts on LST than building density and vegetation coverage. [ABSTRACT FROM AUTHOR]

Highlights • The impact of land cover on microclimate and indoor thermal comfort was studied. • Maximum measured UHI in Manchester was 2.3 °C at 4:00. • Maximum cooling impact of the campus park was during the hottest hours of the day. • 17% more trees in the campus improved indoor thermal comfort by up to 20.8%. Abstract Higher air temperatures in large cities like Manchester, UK, reduce human thermal comfort. In this paper, the impact of land cover on microclimate, and consequently on indoor thermal comfort is studied. Through different stages, field measurements and computer modelling were carried out for a heat wave episode in summer 2017 in Manchester: First, the urban heat island (UHI) was measured between the city centre of Manchester and the campus of the University of Salford (between May to October 2017). Maximum detected UHI was 2.3 °C at 4:00, during the hottest day of the year. Parallel measurements within the university campus showed that the park was 0.9 °C cooler than the paved areas (maximum cooling effect was 3.6 °C at 14:45). Finally, the impact of the current land cover of the campus, and a greener land cover (as a renaturing scenario) with more planted trees on indoor thermal comfort of a house within the campus were studied. It was found that by adding 17% more trees to the campus, indoor thermal comfort was improved by 20.8% during the hottest day of 2017 in Manchester. These showed that renaturing cities could be a solution for future warmer climates. [ABSTRACT FROM AUTHOR]

Abstract Urban redevelopment practices have received substantial attention in urban planning. Remotely sensed thermal infrared monitoring of urban heat island (UHI) is a well-documented topic, however, there is a lack of understanding of the influence on UHI change caused by urban redevelopment process. The objectives of this study was to investigate the urban redevelopment-induced efforts incorporating remote sensing of UHI and land use change. Multi-temporal ASTER thermal infrared images were employed to characterize UHI change; and high resolution Worldview images were employed to perform land use classification. UHI dynamic was quantified with urban heat island ratio index. Analysis of urban redevelopment-induced land use change with response to UHI were carried out. Landscape ecology methods were employed to quantitatively identify land use change with landscape metrics. Result demonstrated that UHI effect had a trend of mitigation during urban redevelopment process in the study area. Urban heat island intensity could be significantly eliminated or weakened by changes of land use composition and spatial configuration. These phenomena were closely related to redevelopment practices such as industrial relocation, buildings demolition, and brownfield transformation. This article presented a case study for characterizing urban redevelopment process with remote sensing monitoring, quantifying the change with urban heat island ratio index and landscape ecology analysis, research findings could be utilized as indicators for urban planning. [ABSTRACT FROM AUTHOR]

Urban is a term that describes anything related to cities or densely inhabited places. It is often employed to define the traits, way of life, and problems unique to metropolitan locations. An extensive range of social, cultural, and economic activities may be found in urban regions, also noted for their dense population density and robust infrastructure. Tall buildings, congested streets, well-established public transit systems, and a diversity of residential, commercial, and industrial zones are just a few characteristics that set it different from other cities. The most significant urban environmental issue is urban heat island studies, and cities worldwide are experiencing terrible circumstances due to urbanization, industry, population strain on the transportation system, and climate change. Sao Paulo, Brazil, and South America have experienced rapid urbanization and growth over the past few decades. The city has experienced massive infrastructure expansion, modernization, and higher living standards due to a burgeoning population and a booming economy. Given the challenges this rapid expansion has also produced, such as traffic congestion, environmental problems, and resource demands, a sustainable urban planning approach is necessary for a balanced growth trajectory. The detection of the urban heat island in the Sao Paulo area using remote sensing and GIS techniques. Over four decades, from 1992 to 2022, many components have been researched, including NDVI, NDBI, LST, UTFVI, and UHI. According to NDVI statistics, healthy vegetation was generally (0.86, 0.96, 0.58, and 0.58) in 1992, 2002, 2012, and 2022—continuous declines from 1992 to 2022, as determined by NDVI data. Overall, the NDBI analysis shows little habitation in 1992 and a significant increase by 2022. LST research findings indicate that the land surface temperature was lower in 1992 and much higher in 2022. Because of UTFVI, fewer condition zones were occupied in 1992; over the years, this number grew. Overall data point to UHI covering a sizable area in 2022. • Urban heat island mapping using remote sensing and geospatial application. • Analysis of NDVI, NDBI, LST, UTFVI, and UHI for Sao Paulo City, Brazil, South America. • Urbanization impact analysis for Sao Paulo City, Brazil, South America. [ABSTRACT FROM AUTHOR]

Urban growth and development caused by urbanization influence the urban heat island (UHI) phenomenon. With the rapid development of urbanization, China's major cities are facing more serious climate change problems, especially the UHI phenomenon. Proper planning and urban design of compact cities may improve the ventilation of street canyons and change the heat balance in the urban canopy and thus mitigate the UHI phenomenon. The aim of this study is to evaluate and discuss the mitigation of UHI with different types of land-use and land-cover (LUCC), as well as different development patterns for compact cities. To this end, we applied the weather research and forecasting model (WRF) with urban canopy model (WRF/UCM) in this study. To evaluate the impact of LUCC changes on the UHI, we set 2 cases based on land use and land cover statistical data from 1965 and 2008 of Wuhan. Also, to evaluate the impact of urban morphology changes on the UHI, we designed 2 hypothetical cases based on 2 different urban developing patterns, one is high rise case and another is high density case, to simulate the impact of urban morphology on the UHI. As for the results of this study, with different LUCC of 1965 and 2008, UHI intensity of Wuhan increased by 0.2 °C–0.4 °C in average. Moreover, the critical wind speed which can mitigate UHI of case 1965 is much lower than case 2008. With different urban morphology, the high-rise case may lead to lower UHI intensity at the pedestrian level due to the shading effects of high-rise buildings. However, the critical value of wind speed in the high-rise case was almost 1.5–2 times greater than that of the high-density case, which illustrates the reduced possibility of mitigating the UHI phenomenon for high-rise buildings in Wuhan City. [ABSTRACT FROM AUTHOR]

An urban heat island is one of the most vital environmental risks in urban areas. The aim of this study was to assess the spatial-temporal patterns of land use changes and heat island intensity for the city of Babol, Iran, between 1985 and 2015 and to predict likely future heat island intensity variations. Multi-temporal Landsat images were acquired and analysed in this study. First, single channel algorithms were used to calculate the land surface temperature (LST), and a Maximum Likelihood Algorithm was utilized to classify images. Second, land use changes (LUCs) and LST were examined, and the relationship between the fractional vegetation cover (FVC) and land-use changes was analysed using the normalized land surface temperature. By using the mean and the standard deviation of the normalized thermal images, the area was divided into five thermal categories: very low, low, medium, high and very high. Then, by applying the heat island intensity index, the heat island changes in the studied period were investigated. Possible future land use changes were investigated using a cellular automata-Markov model, and the heat island intensity changes were anticipated. The results indicate that the area of built-up land increased by 92% between 1985 and 2015, and that the area of agricultural land noticeably decreased. The built-up land changes trend has an inverse relationship with the trend of FVC changes and follows the same trend as the normalized surface temperature changes. Most changes in the surface temperature of the area are located within 0–800 m of a built-up area. The main reason for these changes could be the conversion of agricultural and green space land areas into built-up land. The largest area of the temperature categories in all years is the medium temperature category, which covers the suburban land areas. The low- and very low-temperature categories, which follow a decreasing trend, are related to land areas far from the city. In addition, the high- and very high-temperature categories, whose areas increased annually, are adjacent to the city core and the exits from the city. The average surface temperature in all land uses increased during the studied period. Nevertheless, the rate of temperature rise is higher in the built-up uses. The index ratio of the heat island during this period shows an increasing trend, and its value changed from 0/5 in 1985 to 0/67 in 2015. An increase in the heat island intensity has a direct relationship with the area population growth and, thus, the increase in the built-up land area. Anticipation of land use changes and the process of heat island intensity variations for the studied area show alarming results that call for decision-makers to address this important challenge. [ABSTRACT FROM AUTHOR]

The extreme effects of urban heat island (UHI) on energy consumption, air quality, and human health are significantly detrimental. Increasing the albedo of urban surfaces has been proposed as a potentially efficient mitigation strategy. In this study the Weather Research and Forecasting (WRF) mesoscale model has been used to simulate the urban climate of Rome (Italy).Four different scenarios have been analyzed: the Base Scenario as control case; the Base-ALB Scenario, in which the albedo of roof, walls and road have been increased; the Morph Scenario in which the morphology of urban area has been parameterized more accurately; the Morph-ALB Scenario in which the urban albedo of the improved model has been increased. This study demonstrates that a more accurate parametrization of the urban morphology leads to a more accurate representation of UHI phenomenon. The simulation results show that albedo increase leads to the decrease of the 2-m air temperature at day-time and at night-time. Albedo increase offers very promising results in terms of UHI mitigation, reducing the temperature in the urban area by up to 4 °C at daytime and a little increased (up to 1 °C) in some locations at night time, compared to the control cases. [ABSTRACT FROM AUTHOR]

Climate change and its effect on human life and comfort have taken increase attraction. In this paper effect of UHI is analyzed using quantitative thermal, temporal remote sensing and GIS techniques. Series of Landsat TM/ETM, 8 and ASTER images of Suez Governorate acquired in winter season were used to investigate the variation in land surface temperature (LST) from 1988 to 2014 as well as land-use/cover change. NDVI NDBI and LST have been used for classification of the study area. Vulnerable areas for UHI have been assessed over Suez district. The effect of UHI was quantitatively described using urban thermal field variance index (UTFVI). Results indicate that there are increases in the overall temperature between years 1988 and 2014. Suez and Al-Arbin districts which are the most populated, highly density built-up and rarely vegetation zones in Suez governorate experiences a huge problem of UHI. UHI phenomenon represents total weight of 40.84% and 46.3% of their areas respectively. It is found that the mean temperature of UHI areas of Al-Arbin and Al-Suez districts was 7.5 above mean of District temperature. While the value of UHI of suburban zone e.g. Ataqa and AL-Ganayin was 2.5 degree above district mean. The results indicate that changes in UTFVI distribution can be predominantly related to the expansion of urban area during the study time period. The hot spot of UTFVI were found mainly in the built-up areas especially densely populated district and in heavily industrial district. It is the vulnerable areas to UHI. [ABSTRACT FROM AUTHOR]

• Public transport stops in cities can be transformed into self-sufficient short-stay climate shelters. • Radiant cooling can be used in an innovative way for thermally conditioning urban open spaces. • The prototype bus shelter presents notable efficacy in conditions with temperatures over 30 °C, with a radiant flux of over 50%. • The creation of a digital model, using the Q-COMFA method, may improve the planning of climate shelters in cities. • The feeling of thermal discomfort decreases by between 40 and 50% when the prototype is in operation. In response to the challenges posed by climate change and the growing heat patterns in cities, this study addresses the design and implementation of climate shelters integrated into public transport stops through the installation of surface radiant cooling modules. The aim is to improve the thermal comfort of short-stay users in cities in hot, dry climates. To this end, a fully sensorized thermal camera was used in a controlled setting to simulate real outdoor climate conditions and evaluate the efficacy of the radiant system. The prototype was modelled and characterized by means of in situ measurements, paying special attention to the temperature and radiant heat flux. The radiant modules maintained a temperature between 18 °C and 20 °C, even under oppressive conditions, with over 50% of the cooling flux due to radiation. The radiative performance of the prototype did not increase proportionally with increased water flow, stabilizing at high flows. The analysis of the thermal comfort index showed a decrease in feelings of discomfort of between 40% and 50% when the modules reached the set point temperature. The study shows that implementing these climate shelters in public transport stops such a bus shelters is feasible in hot, dry climates. This may be an effective strategy for mitigating the effects of climate change in urban areas and can be applied in any city that suffers from recurring heatwaves, thereby improving living conditions for city goers. [ABSTRACT FROM AUTHOR]

Growing urbanization over the past decades has increased energy consumption and vehicle usage across the world, which in turn has contributed to the phenomenon called urban heat island (UHI) effect. The most important variable to characterize UHI is the urban-rural air temperature differential. This study aims, generally, at deriving a correlation between air temperatures measured at ground weather stations and land surface temperatures estimated using remotely sensed thermal infrared data. Alternatively, we correlate the air temperature directly to the infrared data. Artificial neural network modelling is shown to be superior to other approaches. While weather stations can be costly to install and maintain, satellite images have become more accessible with technological advances and offer greater land coverage. It is therefore relevant to find the most accurate correlation in order to enable future studies to access air temperature values without the need for ground stations. Another important contribution is the assessment of the conditions of portability of the correlation model derived for one geographical location to another nearby location. This will enable to cover a large range of land with inputs from the same 'reference' ground station. The application of this correlation has demonstrated to be valid for high temperatures, which justifies its applicability in the Middle East region, and more so in Abu Dhabi where automobile and air conditioning usage is high, increasing the effects of UHI. [ABSTRACT FROM AUTHOR]

Cool materials benefits for the mitigation of the urban microclimate overheating caused by Urban Heat Island (UHI) effect are well-established at international level. Since the need for building energy efficiency is more and more pushing towards highly insulated envelope, there is a growing need for studies that address the correlation between the optical properties of building coatings and the thermal transmittance of the envelope where they are applied, also assessing their mutual impact on the UHI. The present paper reports a study, carried out through a fluid-dynamic microclimate simulation software in an Italian urban context, aiming at understanding the impact of the combination of several roof covering optical properties and building envelope U-value levels on the UHI, given the recent nation threshold values for both. The outcomes of the simulations, performed in urban contexts with a typical morphology of Italian town centres and under different climatic conditions, highlight how the increase of the environment air temperatures is influenced by the combinations of the following factors: lower urban canyons, roof surfaces with low solar reflectivity and highly insulated envelopes. In fact, the high insulation levels, in response to current regulatory standards for the reduction of winter energy consumption, inhibit the ingoing thermal fluxes (thermal decoupling phenomenon) leading to an increase of the external surface temperatures and consequently heating up the surrounding area. In this regard, the adoption of reflective materials can be beneficial in attenuating the overheating. Simulation results demonstrate that these materials are able to mitigate the outdoor air temperature until 2°C, depending on specific building envelope configurations and geographical locations. [ABSTRACT FROM AUTHOR]

Weather data plays an important role for energy performance assessment in the design of buildings and urban environments. Many researches have been carried out to generate and analyse various weather files for different simulation platforms. However, investigations have been lacking in the development of weather files reflecting on urban texture variables that account for urban heat island (UHI) problems. The objective of this research is to demonstrate the importance for creating a micro-scale typical meteorological year (TMY) weather file that is based on actual urban texture values. A method is demonstrated to generate new TMY weather files for different micro-scale areas in Singapore based on recent years’ weather data. A comparative impact analysis is made between using the current weather file and the new weather files in terms of energy consumption. Based on the results, the dry bulb temperature of the new TMY is 1–2 °C higher, while the energy consumption prediction increased from 3.25% to 11%. Comparing with actual energy consumption figures the results show to be closer than when using the old TMY. Hence the new weather files will be more credible than the original TMY for energy performance simulation in the design process. [ABSTRACT FROM AUTHOR]

The main objective of this study is to evaluate the genuine effect of green roofs on Tehran's microclimatic conditions and air quality parameters. Two buildings with different roof covers (green and bitumen roof) were selected and air temperature, relative humidity and carbon dioxide concentration data loggers were installed on both of them in two different conditions. Also, the effect of roofs materials on indoor air temperature, heat exchange and energy consumption of each building was assessed by installing internal thermometer inside the rooms to study the indoor thermal conditions of the buildings. Results demonstrated that average air temperature above the green roof was 3.06 and 3.7 °C cooler than that of reference roof inside and outside the screen box, respectively. Also, RH above the green roof was 11.94 and 8.46% higher than the reference roof inside and outside the screen box, respectively. Furthermore, the average air CO 2 concentration inside and outside of the screen box above the green roof during the studied period was 27.98 and 20.71 ppm lower than the reference roof. Similarity, interior spaces of the buildings with green roof showed lower measured air temperature than buildings with bitumen roof. [ABSTRACT FROM AUTHOR]

• A simplified process to obtain UHI measurements through mobile transects is developed. • A low-cost device is connected to a new APP, which performs the UHI calculations automatically. • The results may be exported easily and viewed in the APP with graphs and maps. • An additional web-based tool is included, to obtain maps with spatially-continuous data. • The method has the potential for crowdsourcing, extending UHI data acquisition around the world. The main purpose of Urban Heat Island (UHI) studies and the monitoring of ambient temperatures at large scales is to gather temperature information in a certain area, so as to understand temperature heterogeneity and its drivers or detect locations that lack thermal comfort. However, these studies originate mostly from some research projects, with sufficient budget and manpower to carry out the measurements and the necessary calculations. Thus, there is a scarcity of air temperature information, making it difficult to implement appropriate mitigation actions worldwide. The present work aims to greatly simplify the process to monitor air temperatures and carry out UHI estimations through mobile transects. This is done by introducing the design of a low-cost device and a new APP, which performs automatically most necessary UHI calculations. A web tool based on the Inverse Distance Weighting interpolation method is also included to obtain heat maps. The methodology is illustrated using case studies in Seville (Spain) and New York city (USA). By introducing a straightforward and reproducible methodology, we aim to open the path for a more widespread availability of ambient temperature data anywhere in the world, without the need for costly equipment and many hours of dedication by the researchers. [ABSTRACT FROM AUTHOR]

The resilience of bacterial and fungal spores to common decontamination methods is a major concern in several fields including food industry. In contaminated products, those latent forms can lead to a delayed microbial development with potential hazardous health effects. This study investigates the efficiency of an ultra-high irradiance (UHI) LED device to induce inactivation of spores Bacillus cereus , Saccharomyces cerevisiae and Penicillium spp. Suspensions of bacterial and fungal vegetative cells and spores were exposed to UHI 385 and 405 nm light for periods up to 30 min. The 385-nm wavelength showed a higher potential than 405 nm with a reduction of S. cerevisiae spores of 4.2- and 0.8- log 10 CFU/ml after 30 min, respectively. Similar results were observed on B. cereus endospores with a 4.2 log 10 CFU/ml reduction after 30 min at 385 nm. As expected, due to the documented resistance of spores, the doses required inactivating vegetative cells of B. cereus and S. cerevisiae were significantly lower with a 4.5-log 10 CFU/ml reduction achieved after 2 and 15 min at 385 nm, respectively. After a 15-min treatment, spore population of the filamentous fungi P. digitatum and P. expansum were reduced by 4 and 1.5 log 10 CFU/ml, respectively. The application potential of UHI 385-nm has been assessed in a challenge test on infected mandarins. After 6 days, a reduction of mycelial and sporulation areas of 72% and 85%, respectively, has been observed on treated fruits. Great promises go along with UHI 405 and 385 nm light treatment for applications in fields where microbial resistance is a hurdle. • Short blue light treatments with a UHI LED-based device inhibit microbial spores. • Treatment at 385 nm shows more efficiency than 405 nm. • Reduction of fungal spoilage of fruits can be achieved with adjusted short treatments. [ABSTRACT FROM AUTHOR]

Today the most substantial threats facing cities relate to the impacts of climate change. Extreme temperature such as heat waves and the occurrence of Urban Heat Island (UHI) phenomena, present the main challenges for urban planning and design. Climate deterioration exacerbates the already existing weaknesses in social systems, which have been created by changes such as population increases and urban sprawl. Despite numerous attempts by researchers to assess the risks associated with the heat-health nexus in urban areas, no common metrics have yet been defined yet. The objective of this study, therefore, is to provide an empirical example of a flexible and replicable methodology to estimate the micro-scale UHI risks within an urban context which takes into account all the relevant elements regarding the heat-health nexus. For this purpose, the city of Turin has been used as a case study. The methodological approach adopted is based on risk assessment guidelines suggested and approved by the most recent scientific literature. The risk framework presented here used a quantitative estimate per each census tract within the city based on the interaction of three main factors: hazard, exposure, and vulnerability. Corresponding georeferenced maps for each indicator have been provided to increase the local knowledge on the spatial distribution of vulnerability drivers. The proposed methodology and the related findings represent an initial stage of the urban risk investigation within the case study. This will include participatory processes with local policymakers and health-stakeholders with a view to guiding the local planning agenda of climate change adaptation and resilience strategies in the City of Turin. • Example of a flexible and replicable methodology to estimate the UHI risks within cities. • First micro-scale UHI risk assessment investigations with this methodology in Italy. • An insight into indicators and metrics to assess the impacts of climate change. • A methodology to support developing policies towards a more climate-resilient future. [ABSTRACT FROM AUTHOR]

The planting of trees in streets and parks is critical for urban greening efforts that seek to improve climate-change resilience in cities around the world. Ecosystem services provided by urban trees range from mitigating urban heat island effects to enhancing human well-being and conserving native biodiversity. At the same time, such tree services trade off with disservices that include risk to human safety from falling branches and infrastructure damage from root growth. Here, we performed a survey of residents of a sub-tropical region in eastern Australia to determine community perceptions of the ecosystem services and disservices linked to urban tree plantings. Our aim was to better understand the diverse perceptions of the community, prior to on-the-ground implementation of urban greening, to help guide planting programs in streets and parklands that are vulnerable to UHI effects in the region. We found strong evidence for a high level of public awareness about the beneficial ecosystem services that urban trees can provide. A broad spectrum of beneficial tree services were valued highly by the community in their urban environment including the planting of native trees that can attract and provide food for preferred wildlife; provide shade and reduce heat; allow for a strong connection with nature; have the potential to store carbon to mitigate climate change; provide a level of protection from bushfires; have aesthetically pleasing properties; and produce food for people. At the same time, however, community concerns about tree disservices were concentrated primarily on root damage to infrastructure as well as property damage and injury from falling branches. Our elicitation of community attitudes to tree services and disservices will allow for residents' most important values and strongest concerns about trees to be explicitly taken into account when establishing a community-inclusive approach to urban tree planting. [ABSTRACT FROM AUTHOR]

Characterisation of the effects of varying atmospheric mixing states (stability) in urban climate studies has historically been hampered by problems associated with the complexity of the urban environment, representativity of measurement techniques, and the logistical and financial burdens of maintaining multiple long-term comprehensive measurement sites. These shortcomings, together with a lack of a consistent measurement approach, have limited our ability to understand the physical processes contributing to the urban heat island effect. In this study, we analyse 4 years of continuous hourly near-surface meteorological and atmospheric radon data from an urban–rural site pair in central Poland. A recently-developed radon-based stability classification technique, previously developed for urban pollution characterisation, is employed to characterise the Urban Heat Island Intensity (UHII) and other climatic factors over the full diurnal cycle by season and atmospheric mixing state. By characterising the UHII over a range of atmospheric mixing states in a statistically robust way, this technique provides an effective tool for assessing the efficacy of mitigation measures for urban climate effects in a consistent way over timescales of years to decades. The consistency of approach, ease of application, and unprecedented clarity of findings, provide a strong argument for atmospheric radon observations to be included as part of the ‘standard measurement suite’ for urban climate monitoring networks for non-coastal cities. [ABSTRACT FROM AUTHOR]

Increased population and rapid urban development have raised the consumption of energy and affected to the urban environment. It creates the rising temperature in certain areas that is called urban heat island (UHI) phenomenon. Mitigating UHI on the most influencing factors based on the characteristics of a certain city is important due to the effectiveness and efficiency of the purposing strategies. As a matter of fact, municipality and community are lack of awareness to the activities that worsening UHI in urban development. This research therefore analyzes significant factors influencing UHI in Surabaya city, one of the metropolitan cities in Indonesia. A mixed method using city development documents and statistical data related to (Urban Heat Island Intensity), changes in surface cover, use of air conditioning and greenhouse gases has been applied in this study. The results show that provision of green space, electricity consumption and use of asphalt are the significant factors that influence UHI in the city. Furthermore, consideration to development and management of environment related strategies and measures is being needed. Municipality can focus to implement or establish for emphasizing most significant factors. Hence, this result can be a reference to mitigate UHI in Surabaya or other cities with similar characteristics. [ABSTRACT FROM AUTHOR]

Climate change projections estimate a rise of approximately 3 °C by the 2080s for most of the UK (medium emissions scenario at 50% probability level, 1961–1990 baseline). Warming is a particular concern for urban areas due to urban densification and the Urban Heat Island (UHI) effect. To counteract the UHI, one adaptation strategy for urban areas is increasing the proportion of greenspace, such as parks, street tree plantings, and green roofs. This research employed an interdisciplinary approach to measure and model fine-scale microclimate changes due to greenspace and explore the implications for building energy demand in Manchester, UK. Both the modelled and measured microclimate data informed development of a series of weather files for building energy modelling of three commercial building types. For a scenario adding 5% mature trees to the urban case study, the combination of microclimate modelling and data analysis estimated a maximum hourly air temperature reduction of nearly 1.0 °C under peak UHI conditions and wind speed reductions up to 1.0 m/s. These results were used to change the weather files in the building energy modelling, which estimated a reduction of 2.7% in July chiller energy due to the combination of reduced UHI peak hours and eight additional trees shading a three-storey shallow plan building. Energy savings increased to 4.8% under a three-day period of peak UHI conditions. [ABSTRACT FROM AUTHOR]

Urban heat island (UHI) is an important issue of regional thermal environment in urban climate, which is affected by airborne particulates. However, the influences of various aerosol compositions on the UHI have been rarely reported. This study investigates the radiative effects of particulates on regional thermal environment and the UHI intensity (UHII) in the YRD during January 2018 using the WRF-Chem model. The model performs reasonably in reproducing the observed evolutions of the key meteorological fields and air pollutants. Our results show that the UHI effect is prevalent over megacities of the YRD, with markedly higher surface UHII compared to the canopy one. The UHI effect generally gets more significant during nighttime and reaches the maximum in the late afternoon. Fine particulates nonlinearly reduce the surface and air temperature, which lowers the UHII throughout the day, but significant differences exist among different UHI indices. We highlight that these influences are predominantly attributed to the radiative effect of sulfate, nitrate, and ammonium aerosols. As a comparison, the effects of organic aerosols are much less and black carbon reduces the UHI almost negligibly. This study would contribute to a comprehensive understanding of radiative effects of aerosols on the UHI. • The UHI reaches the minimum and maximum in the late morning and late afternoon, respectively. • Airborne particulates can significantly reduce surface and air temperature via the aerosol-radiative effect, which lowers the UHII. • The influence is predominantly attributed to the radiative effect of sulfate, nitrate, and ammonium aerosols. • Black carbon exhibits a warming effect, but negligibly reduces the UHII due to its low mass loading. [ABSTRACT FROM AUTHOR]

Cold environment supports a large diversity of local climates. Among them, urban climates in northern cities stand out for their pronounced warm temperature anomaly known as the Urban Heat Island (UHI). UHI in northern cities has been already studies through satellite images and in-situ observations in the urban canopy layer (UCL). Yet, the vertical structure of the urban atmospheric boundary layer (UBL) has not been studied there. This work presents new observations of UBL in Nadym – a sub-Arctic Siberian city. During several intensive observing periods we run simultaneous registration of urban and rural meteorological parameters with unmanned drones, a microwave temperature profiler and a dense network of ground-based sensors. The data analysis reveals details of UHI development in the UCL and UBL, and links together horizontal urban-rural canopy-layer temperature differences, boundary layer stability, and UHI vertical extent. We show that during strong temperature inversions, UBL is less stratified than its rural counterpart, but it still remains very thin and limited in height by a few tens of meters. The observations disclose that the ground-based (50 m – 100 m above ground) temperature inversion is one of the strongest control factors for UHI in cold climate conditions in winter. • ABL over a cold-climate city was observed using drones and microwave temperature profiler in very cold winter conditions • Intense canopy-layer UHI appears when stable ABL with a strong ground-based temperature inversion develops over rural area • In such conditions, the urban boundary layer typically remains well-mixed, but is limited in height by only about 50 m • Strength of the ground-based inversion is one of the strongest controls for UHI in a cold-climate city in winter [ABSTRACT FROM AUTHOR]

The urban heat island (UHI) is an important phenomenon due to its direct and indirect impacts on the health of the population residing in urban environments. Very few studies have been conducted on the relationships between UHI and outdoor thermal comfort in the Amazonia biome. In this work, we analyzed the behavior of hourly variability of the UHI, heat index (HI), thermal discomfort, and Land Surface Temperature (LST) in Manaus (Brazil). The novelty of the study is to assess the degree of alteration of the UHI with changes in vegetation cover in the Amazon biome. Temperature and air humidity data were collected from six weather stations from July 2013 to July 2014. In addition, satellite images of the TM and OLI/TIRS sensors onboard the Landsat 5 and Landsat 8 satellites for the years 1987, 1998, 2007, and 2015 were used. The intensity of the UHI increased during the analyzed period. The weather stations located in the urban area had temperatures above 30.0 °C, while the temperatures in the rural area ranged from 25.0 to 26.5 °C. As a direct implication of the results found, it is noted that in Manaus, the UHI can reduce thermal comfort in urban spaces, directly impacting people's quality of life and health. The periods with the least amount of precipitation in the city (August and September) can generate thermal discomfort inside houses during the night period, meaning an increase in the number of hours in which people are exposed to heat. [Display omitted] • Southern Manaus presented higher values of UHI and HI. • The average UHI was approximately 4.0 °C. • Substantial increase in LST over the last decade. • Atmospheric UHI and HI were well evidenced at night. • Surface UHI is present at all hours of the day and night. [ABSTRACT FROM AUTHOR]

Remotely sensed Land Surface Temperature (LST) is widely used to characterize Surface Urban Heat Island (SUHI) intensity and spatial variability. SUHI may differ significantly from the Urban Heat Island (UHI), which is related to air temperature and is more representative of human wellbeing. The lack of information and results on UHI development is due to the difficulty in having measurements with high spatial density within the city and the uncertainties in finding relationships between air and surface temperatures. Characterizing UHI is fundamental when dealing with human thermal wellbeing especially when extreme events occur. A new index, named Urban Heatwave Thermal Index (UHTI), was presented here to quantify daytime air temperature variability patterns in an urban environment during a meteorological heatwave. UHTI integrates a) air temperature recorded by local sensors; b) structural microclimatic Envi-met fluidodynamic modeling simulations; and c) remotely sensed environmental indicators. UHTI is a reliable representation of thermal criticalities in the city for its inhabitants. A case study on Bologna (Italy) municipality is presented. Moreover, UHTI was calculated and compared with the Urban Thermal Field Variance Index (UTFVI), commonly used for urban climate characterization. Results showed a high degree of correlation (R2 = 0.795) between the two indexes; residual mapping and hot-spot detection indicated that their biggest differences are next to dense urban fabric areas like historical centers and water body areas. • A new index, named Urban Heatwave Thermal Index (UHTI), is presented here. • UHTI depicts daytime air temperature patterns in urban areas during a heatwave. • UHTI integrates: a) ground data, b) satellite data and c) Envi-met modeling output. • A case study on Bologna (Italy) municipality is presented. [ABSTRACT FROM AUTHOR]

The purpose of this study is to investigate different heat mitigation strategies and determine the optimal choice for old neighborhoods renovation. A residential building with the parking lot in front of it was selected as the research object. Various critical factors affecting outdoor thermal condition, such as tree location, pavement material, wind speed and direction, "hedge" type, were simulated and examined with ENVI-met and Rayman model. Air temperature, mean radiant temperature (MRT), physiological equivalent temperature (PET) were used to assess the outdoor thermal comfort level. The results show that: 1) concrete replacing asphalt as pavement material could effectively lower air temperature; 2) planting trees on the west or south side is a better choice in creating a more thermally comfortable outdoor environment when available space is limited in the targeted area; 3) compared with wind direction, wind speed has a more significant influence on outdoor thermal condition; 4) water body's cooling efficiency is superior to that of grassland. The findings of this study could provide useful guidance in the process of renovating old neighborhood in the city. • Planting trees on the west or south side of the study area could provide more cooling benefit. • Compared with wind direction, wind speed has a more significant influence on outdoor thermal environment. • Concrete replacing asphalt as pavement material could effectively lower air temperature. • Water body's cooling efficiency is superior to that of grassland. [ABSTRACT FROM AUTHOR]

Urban heat island (UHI) studies have traditionally focused on the relative difference between air temperatures measured at an urban area and those at a rural location, taken as a reference. Whereas the influence of urban areas on UHI intensity has been abundantly explored, the impact of the choice of an adequate rural reference location, due to the frequent agricultural use of rural areas, still remains understudied. The issue of climate variability of rural areas is a determining factor for assessing UHI intensity. Brazil is the world's largest sugarcane producer, with a 33% share of the global market. Many mid-sized cities in the Brazilian state of São Paulo are located close to sugarcane fields, which all undergo the sugarcane growth cycle with defined pre-harvest and post-harvest stages. The aim of this study is to understand the interference of seasonal harvesting periods in sugarcane plantations on the development of UHI magnitudes in and around (at suburban locations) Piracicaba, located in the state of São Paulo, Brazil, at 22° 42′ 30" S and 47° 38' 01" W and characterized by Köppen-Geiger's Cfa, humid subtropical climate. We deployed a fully-equipped weather station at the site of a sugarcane crop at post- and pre-harvest and a small network of three weather stations provided with air temperature and humidity sensors in the city center and in suburban neighborhoods in Piracicaba. Pre-harvest showed the highest UHI intensities, though not confounding the analysis of intra-urban temperature differentiation patterns. Results stress the relevance of the choice of the baseline rural station in terms of temporal variability related to the sugarcane harvesting cycle. • Changes in UHI intensity between two periods analyzed in the sugarcane plantation. • Larger UHI intensity at all points at the pre-harvest stage. • During pre-harvest no observed confounding impacts on intra-urban temperature variability versus LCZ. [ABSTRACT FROM AUTHOR]

Urbanization is known to cause noticeable changes in the properties of local climate. Studies have shown that urban areas, compared to rural areas with less artificial surfaces, register higher local temperatures as a result of Urban Heat Islands (UHIs). Hong Kong is one of the most densely populated cities in the world and a high proportion of its population residing in densely built high-rise buildings are experiencing some degrees of thermal discomfort. This study selected Mong Kok and Causeway Bay, two typical urban communities in Hong Kong, to gather evidence of microclimate variation and sources of thermal discomfort. UHIs were estimated from 58 logging sensors placed at strategic locations to take temperature and humidity measurements over 17 consecutive days each in the summer/hot and winter/cool periods. By employing geographic information and global positioning systems, these measurements were geocoded and plotted over the built landscape to convey microclimate variation. The empirical data were further aligned with distinct environmental settings to associate possible factors contributing to UHIs. This study established the existence and extent of microclimate variation of UHI within urban communities of different environmental configuration and functional uses. The findings provided essential groundwork for further studies of UHI effects to inform sources of local thermal discomfort and better planning design to safeguard environmental health in public areas. [ABSTRACT FROM AUTHOR]

Climate change will lead to more warm and hot days in the Netherlands. Climate adaptation measures are needed to reduce the vulnerability of urban areas. Moreover, proven adaptation measures, such as increased vegetated areas or water surfaces, are not always possible due to a lack of space or undesired aesthetic effects. An alternative option is to make use of coloured façades to create drafts and accelerate wind speed in a street canyon or on a square to attract fresh air from cooler places. Differences in colour and material types already influence the air flow in street canyons in an uncontrolled manner. If this thermal comfort principle can be implemented, it will potentially have a significant impact on many cities throughout the world. This paper presents the results of a first exploratory research based on measurements on scale models and at full scale. This pilot study indicates success of the intended draft principle, advocating further research. [ABSTRACT FROM AUTHOR]

Man-made islands, created by reclaiming land from the sea, have become more prevalent in the Gulf Corporation Council countries (GCCC) in recent years as demand for additional land to develop grows. The creation of such islands will affect the landscape, climate and environment through the replacement of sand and water with hard artificial surfaces and buildings. Exposing urban man-made surfaces, such as roads and buildings, to the sun increases the temperatures of their surfaces and the atmosphere, and consequently impacts upon the local weather, building energy consumption and people's thermal comfort through the modification of microclimatic variables such air temperature, relative humidity and wind speed. The current body of work represents the results of field measurements and simulation studies that assessed modifications in urban temperatures of the man-made AMWAJ Islands in the Kingdom of Bahrain, and examined thermal comfort and cooling energy demand on the islands. This work argues that the urban temperatures of AMWAJ Islands were altered in part due to human contributions such as urban geometry, urban surfaces and land use. The modification in temperature could reach almost 5 °C. In turn, thermal comfort and cooling demand within AMWAJ islands were affected by the modified temperatures. The increase in urban cooling load was within the range of 14–26% when compared with uninhabited islands. The presence of green surfaces, in conjunction with water bodies that overlap with the infrastructure, help to improve thermal comfort and consequently reduce cooling energy requirements in AMWAJ Islands. [ABSTRACT FROM AUTHOR]

Ultra-high-intensity lasers have opened up a new avenue for the creation and detailed spectral measurements of dense plasmas in extreme thermodynamic conditions. In this paper, we demonstrate the possibility of heating a dense plasma ( ρ > 1 gcm −3 ) to a maximum temperature of 560 ± 40 eV using a few-Joule, relativistic-intensity laser pulse. Particle-in-cell, radiation-hydrodynamic and atomic physics simulation tools are used together for a full description of the plasma dynamics, from laser interaction to late-time expansion and x-ray emission, yielding overall good agreement with the spectral measurements. We discuss the sensitivity of our analysis to space-time gradients, non-equilibrium ionization processes and hot electron effects. [ABSTRACT FROM AUTHOR]

• Urban morphology had more influence on MRT/PET during daytime than at night. • 3D urban spatial configuration was more significantly correlated with MRT/PET than 2D pattern. • Local thermal comfort was mainly impacted by BFAR during daytime and by TCCR at night. • Evaluating effects of urban morphology on local thermal comfort should control the effects of BFAR. Urban morphology has significant effects on local thermal comfort. To investigate the correlation between thermal condition and urban spatial configuration, 24 typical scenarios were extracted from complex urban area, and 17 2D/3D indicators were selected to represent urban morphology characteristics. Different statistical approaches were employed to quantify the relationship between the selected indicators and MRT/PET. The results showed: (1) urban morphology exerted more influences on local thermal condition during daytime than at night, leading to the spatial heterogeneity of MRT/PET being much higher in the daytime; (2) the correlations between urban morphology indicators and MRT/PET changed dramatically when using different statistical approaches. This finding highlights the necessity of controlling the effect of building floor area ratio when quantifying the impacts of urban spatial configuration on local thermal comfort; (3) 3D urban morphology indicators were more significantly correlated with local thermal comfort than 2D indicators. Specifically, building floor area ratio and tree canopy coverage ratio were the most important predictor of MRT/PET during daytime and at night respectively. This study could further strengthen our understanding the effects of urban morphology on UHI. It could also offer useful insights to urban planners and decision makers on designing and constructing climate-adaptive urban environment. [ABSTRACT FROM AUTHOR]

The urban heat island (UHI) phenomenon is a serious concern for urban planners and policymakers, requiring effective and efficient mitigation policies. To develop such policies, accurate and pre-emptive estimations of current and future UHI manifestations are vital elements that help determine efficient policies and mitigation techniques. There are two fundamental approaches for modelling overheating in an urban environment: white-box and black-box based methods. The first one is characterized by the easily interpretable working process, while the unclear working procedure defines the second one. The present study comprehensively reviews the commonly used white-box and black-box based approaches applied for UHI predictions, analyses the existing literature adopting these tools for UHI prediction, and discusses the effectiveness of fusing both methods at the design and operation stages of the urban area for effective prediction and mitigation of UHI effect. The literature analysis showed that the transparent working process and high prediction accuracy of the physical-based white-box models make them a popular and reliable tool for UHI evaluation. Nevertheless, some white-box based simulation tools are too complex and require a high level of expertise to operate, leading to potential inaccuracies in the obtained outcomes. Black-box models, in turn, despite their opaque working process, are more straightforward in use and require less computation time. The fusion of these two methods is a novel approach that may benefit both UHI prediction and mitigation at the design and operation stages, respectively. • Current use of white-box and black-box modelling of UHI is discussed. • Future research directions and areas of effective discourse are identified. • Fusion of white-box and black-box approaches for city design stages are discussed. • Coupling White-box modelling and machine-learning for city operations are proposed. [ABSTRACT FROM AUTHOR]

Urban areas are known to have a local climate different from that of surrounding rural landscapes and the temperature difference constitutes an urban heat island (UHI). Despite being described as ‘heating islands’, cities are not isolated from their environment. But only few studies respect the UHI as a relative measure and consider both the drivers of the temperature level of the urban area and of the surrounding landscape in their UHI assessments. A series of 124 Landsat satellite images spanning four decades were used to derive land surface temperatures (LST) of 77 urban areas (between 20 and 1600 ha) and their surroundings in the Province of South Tyrol, northern Italy. These data were used to calculate urban–rural LST differences (ΔLST UHI ) and NDVI differences (ΔNDVI) for quantifying the urban heat island effect. ΔLST UHI were recorded between 1.0 K and 8.1 K, with a mean ΔLST UHI of 4.2 K. The results show pronounced UHI effects already for small cities of less than 1 km 2 , but suggest that the urban size is of only minor importance for the ΔLST UHI magnitude in case of urban areas smaller than about 10 km 2 . Urban–rural land surface temperature difference (ΔLST UHI ) was identified to be primarily driven by ΔNDVI, together with solar irradiance and land use. Threshold values for the occurrence of ΔLST UHI extremes are provided. Implications for landscape and urban planning are presented that underpin the crucial importance of considering the surrounding landscape for quantitative assessments of UHI intensity. [ABSTRACT FROM AUTHOR]

Climate change in cities has received much focus in the past few decades. Heat stress in urban areas has an adverse effect on human health and is expected to worsen in the future due to the global warming. Vegetation has been shown to mitigate this effect, but introducing ‘green’ areas into the metropolitan space is a challenging task. We assessed the thermal load in terms of surface temperature in Tel Aviv, the biggest metropolitan area of Israel. The thermal effect of four different urban land uses was estimated. Specifically, we compared the cooling effect of residential areas with high vegetation cover (referred here as ‘green’ residential) to that of small to medium size (2–40 ha) public parks. To this end, we used satellite data of land surface temperature (LST) and the Normalized Difference Vegetation Index (NDVI), as a surrogate for vegetation cover. High-temporal data were combined with high spatial resolutions data to produce 10-year average LST and NDVI maps at high spatial resolution over Tel Aviv. As expected, industrial areas had the highest LST due to lowest ratio of vegetation to free space area (1%), while ‘green’ areas displayed the lowest LST. Green residential and small-medium public parks had comparable thermal loads, with green residential having slightly lower LST (by 0.5 °C). In general, small-medium public parks displayed higher LST than expected. Inefficient use of free spaces for vegetation, i.e., relatively low vegetation cover to free space ratio, was probably the main cause for this. Public parks had a higher local cooling effect, but a less continuous one on the proximate surrounding (30–90 m from the park), probably due to their relative location in the urban fabric. Our results suggest that ‘greening’ areas within the private urban space should be encouraged at the expense of building new small-medium parks in metropolitan areas that lack the sufficient free space for larger parks. The outcome of this study may have key implications for urban planners seeking to mitigate urban heat island effects under the limitation of existing dense urban layout. [ABSTRACT FROM AUTHOR]

Temporal and spatial trends of the surface urban heat island (UHI) formation over Delhi are examined with respect to aerosol load and land-cover variations. The study reveals that temperatures over Delhi are higher than those over the surrounding regions almost through-out the year during the night time. The nocturnal heat island intensity is minimum (0–2 K) during the monsoon months and maximum during the month of March (4–6 K). The UHI trends during the day-time are however, significantly different. It is observed that a day-time cool island forms over Delhi twice during the year in the months of May–June and October–December. Analysis of temporal variations in urban heat island intensity (UHII) and aerosol load over Delhi reveals a significant negative correlation between UHII and aerosol optical depth (AOD). Spatial analysis of LST, land-cover and AOD for the months of March, May and November confirms the significant role of AOD along with land-cover variables such as percentage area under the classes built-up, rock, vegetation and bare soil. Comparative analysis of LST in the regions lying north, south, east and west of Delhi in relation to the prevailing land-cover suggests that thermal inertia is also a very important factor determining the urban-rural thermal structure. [ABSTRACT FROM AUTHOR]

Urban heat island (UHI) is a global issue as a result of urbanization. Land surface temperature (LST) is closely related to the thermal environment and energy budget of the earth surface, and is an important parameter in identifying UHI effects. Previous studies have proved the effects of landscape pattern on LST by using landscape metrics. However, the metrics used were inconsistent in number and type. Further, fewer studies tried to select representative metrics from the numerous metrics for LST indication. In this study we tried to explore the effects of landscape pattern on LST in Beijing by using the representative class level metrics selected through cluster analysis, factor analysis and regression. The results showed a composition metric such as PLAND (e.g. percentage of impervious surface in a landscape) alone explained about 56% of the landscape mean LST, whereas adding a configuration metric such as LSI (landscape shape index) or Gyrate_MN (mean gyration index) explained approximate another 6-12%. Adding more other configuration metrics does not improve the regression model performance more than 1%. The regression results also revealed that without targeted dependent variables, the factor analysis is of no use for choosing landscape metrics. These indicate that landscape composition and configuration both have effects on landscape mean LST, while composition is much more important than configuration, and that a combination of one composition metric with no more than four configuration metrics of impervious surface is sufficient for LST prediction. These results can help landscape ecologists in using landscape metrics and further help landscape planners to balance land cover in urban planning. [ABSTRACT FROM AUTHOR]

Urban Heat Island (UHI) has become a growing concern to the quality of densely built urban environments, particularly in tropical cities. Wind speed has widely been reported to have decreased the intensity of heat island effect in urban areas. The cooling effect of the wind helps to mitigate the adverse effects of heat island on the micro climate and human thermal comfort. This paper investigates the existence of heat island in Muar, one of the fast growing cities in southern part of Malaysia and its possible causes, and then examines the effects of different urban geometry on the wind flow. The results of this study indicate that the chaotic development in Muar has caused reduced ventilation in urban canyons. The heat island intensity in the city center was recorded as 4°C during the day and 3.2°C during the night. Investigation of various urban geometry modifications showed that step up configuration was the most effective geometry as it can distribute the wind evenly allowing the wind to reach even the leeward side of each building. [ABSTRACT FROM AUTHOR]

Urban heat island (UHI) effects were first observed in London in the 19th century. The urban heat island is identified by developing higher temperatures in urban areas than the surrounding rural areas that directly surround them. However, there are some main mitigation strategies to deal with subtropical UHI, such as increasing the albedo of the urban environment (reflective pavement) and developing the green infrastructure (green roof) in urban areas. This study would analyse the microclimate in a subtropical city by evaluating meteorological parameters with a three-dimensional model simulation software of computational fluid dynamics (CFD) named ENVI-Met. To evaluate Urban Heat Island mitigation strategies for a Subtropical City Centre, subtropical city Osaka, Japan, is selected to investigate UHI with modelling. The simulation has been used to applicate the five scenarios (base scenario, cool pavement scenario, cool roof scenario, increasing vegetation coverage scenario, and integrated scenario) with different albedo and vegetation coverage ratios. In this study, outdoor air temperature, sky view factor, net radiation, mean radiant temperature and thermal radiative power are considered as five criteria for evaluating the efficiency of UHI mitigation strategies. The simulation results of the base model (scenario A) with Osaka's current condition are considered the reference value. The relative percentage differences between each scenario with a base model are determined. The increased albedo of urban fabric material (scenario B Cool pavement model) showed the most efficient to mitigate UHI. The relative percentage differences of the five criteria in the Cool pavement model are more significant than other models. Therefore, the results of this study can provide valuable guidance, both for keeping subtropical residents cooler and informing subtropical climate cities that would be sustainable in the future. • Three main urban heat island (UHI) mitigation strategies in subtropical city centres were reviewed and proposed. • Five scenarios with different albedo and vegetation coverage ratios have been simulated in ENVI-met. • Five criteria are considered as standards to evaluate the efficiency of each UHI mitigation strategy. • The increased albedo of urban pavement fabric material is the most effective way to mitigate UHI in the research city centre. [ABSTRACT FROM AUTHOR]