scholarly journals REMOTE SENSING AND NIGHT TIME URBAN HEAT ISLAND

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 15-22
Author(s):  
B. Arellano ◽  
J. Roca
Keyword(s):  
Heat Waves ◽  
Urban Climate ◽  
Construction Materials ◽  
Thermal Inertia ◽  
Cooling Capacity ◽  
Night Time ◽  
Urban Heat ◽  
Materials Used ◽  
Significant Health

Abstract. The urban climate literature has highlighted the remarkable prominence of nighttime UHI phenomenon. During nighttime the UHI effects become more evident due to the greater thermal inertia of the materials used in urban fabric. It is during the night when the heat accumulated in urban materials, especially in contexts of heat waves, can generate significant health risks. The low cooling capacity of urban construction materials negatively affects the comfort and the health of urban dwellers. However, and despite the great importance of night stress due to heat, the study of night UHIs is still underdeveloped. In this context, this paper aims to determine nighttime LST contrasting Landsat's very limited nighttime images with daytime ones. The example developed refers to heat wave situations during the summer 2015. The case study is the Metropolitan Area of Barcelona (35 municipalities, 636 km2, 3.3 million inhabitants).

scholarly journals Effects of Infills in the Seismic Performance of an RC Factory Building in Pakistan

Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 276
Author(s):  
Nisar Ali Khan ◽  
Giorgio Monti ◽  
Camillo Nuti ◽  
Marco Vailati
Keyword(s):  
Numerical Model ◽  
Construction Materials ◽  
Building Codes ◽  
Construction Technique ◽  
Infill Walls ◽  
Mortar Strength ◽  
Materials Used ◽  
Seismic Response Of Buildings

Infilled reinforced concrete (IRC) frames are a very common construction typology, not only in developing countries such as Pakistan but also in southern Europe and Western countries, due to their ease of construction and less technical skills required for the construction. Their performance during past earthquakes has been in some cases satisfactory and in other cases inadequate. Significant effort has been made among researchers to improve such performance, but few have highlighted the influence of construction materials used in the infill walls. In some building codes, infills are still considered as non-structural elements, both in the design of new buildings and, sometimes, in the assessment of existing buildings. This is mainly due to some difficulties in modeling their mechanical behavior and also the large variety of typologies, which are difficult to categorize. Some building codes, for example, Eurocode, already address the influence of infill walls in design, but there is still a lack of homogeneity among different codes. For example, the Pakistan building code (PBC) does not address infills, despite being a common construction technique in the country. Past earthquake survey records show that construction materials and infill types significantly affect the seismic response of buildings, thus highlighting the importance of investigating such parameters. This is the object of this work, where a numerical model for infill walls is introduced, which aims at predicting their failure mode, as a function of some essential parameters, such as the friction coefficient between mortar and brick surface and mortar strength, usually disregarded in previous models. A comprehensive case study is presented of a three-story IRC frame located in the city of Mirpur, Pakistan, hit by an earthquake of magnitude 5.9 on 24 September 2019. The results obtained from the numerical model show good agreement with the damage patterns observed in situ, thus highlighting the importance of correctly modeling the infill walls when seismically designing or assessing Pakistani buildings that make use of this technology.

Revaluation of Ksar El-Haouita in Laghouat, Algeria

2021 ◽  
Author(s):  
Fatiha Imane Mahcar ◽  
Belkacem Takhi
Keyword(s):  
Morphological Analysis ◽  
Construction Materials ◽  
Architectural Heritage ◽  
Theoretical Underpinning ◽  
Great Resistance ◽  
Basic Principles ◽  
Construction Techniques ◽  
Materials Used ◽  
Local Materials

Algeria has a rich urban and architectural heritage, which presents regional specificities. Once the ksour was a symbol of balance and perfect harmony with its environment, unfortunately today they no longer reflect their former function. The Ksourian architecture, including that of Laghouat is a prestigious heritage of high value; it is the testimony of genius knowledge and the capacity of their occupants to adapt to the difficult environment. The housing is considered the essential core of this architecture it represents the entire composition of the ksar, its design is inspired by the immediate environment and respects ancestral social values. It is characterized by a simple architecture and simple construction techniques which are based on the construction in load-bearing walls, the construction materials used are local materials of great resistance and less expensive. This study addresses the theme revaluation of heritage, particularly our case study ksar El-Haouita which has experienced a neglecting and depopulation due to several factors. The ksar El-Haouita is among the most famous ksour located in the south of Algeria and exactly in the region of Laghouat. It is built with simple materials and techniques of construction. The construction materials used are local materials like stones and lime found in the environmental surroundings of the ksar. The aim of this study is to identify the major causes of the degradation of ksar, also to preserve ksar El-Haouita through specific operations and to improve the tourist attractiveness of ksar El-Haouita in order to promote heritage, to convert it back into sustainable Saharan tourism. Our study based in the first place; on a theoretical underpinning which contains the notions that have a relation with our theme, the problematic and the envisaged objective, then a presentation of ksar followed by a morphological analysis accompanied by identification of the problems to identify the phenomena of damage and its disfigurement. The last step is to treat an aspect for the development of ksar, this aspect is devoted to the restitution of the defensive system (doors, ramparts, ramparts of houses and towers) of the ksar, through a diagnostic and several operations like (rehabilitation and reconstruction). The aim result of this study is to show that the revaluation of the ksar is a very vast operation and proposes interventions that allow the preservation of the ksar and also to understand the elements that help the success of interventions and to put some of the parameters considered as reference elements and basic principles for the operations on the ksar and among these operations it is (the case study, which is the restitution of the defensive system of ksar El-Haouita).

scholarly journals Advancement in Urban Climate Modelling at Local Scale: Urban Heat Island Mitigation and Building Cooling Demand

Atmosphere ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1313
Author(s):  
Aytaç Kubilay ◽  
Jonas Allegrini ◽  
Dominik Strebel ◽  
Yongling Zhao ◽  
Dominique Derome ◽  
...  
Keyword(s):  
Climate Model ◽  
Heat Waves ◽  
Urban Climate ◽  
Building Energy ◽  
Urban Heat Islands ◽  
Heat Island ◽  
Meteorological Model ◽  
Heat Islands ◽  
Urban Heat ◽  
Building Cooling

As cities and their population are subjected to climate change and urban heat islands, it is paramount to have the means to understand the local urban climate and propose mitigation measures, especially at neighbourhood, local and building scales. A framework is presented, where the urban climate is studied by coupling a meteorological model to a building-resolved local urban climate model, and where an urban climate model is coupled to a building energy simulation model. The urban climate model allows for studies at local scale, combining modelling of wind and buoyancy with computational fluid dynamics, radiative exchange and heat and mass transport in porous materials including evaporative cooling at street canyon and neighbourhood scale. This coupled model takes into account the hygrothermal behaviour of porous materials and vegetation subjected to variations of wetting, sun, wind, humidity and temperature. The model is driven by climate predictions from a mesoscale meteorological model including urban parametrisation. Building energy demand, such as cooling demand during heat waves, can be evaluated. This integrated approach not only allows for the design of adapted buildings, but also urban environments that can mitigate the negative effects of future climate change and increased urban heat islands. Mitigation solutions for urban heat island effect and heat waves, including vegetation, evaporative cooling pavements and neighbourhood morphology, are assessed in terms of pedestrian comfort and building (cooling) energy consumption.

scholarly journals Large model structural uncertainty in global projections of urban heat waves

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Zhonghua Zheng ◽  
Lei Zhao ◽  
Keith W. Oleson
Keyword(s):  
Heat Waves ◽  
Global Climate ◽  
Urban Climate ◽  
Central India ◽  
Structural Uncertainty ◽  
Single Model ◽  
High Stake ◽  
Socioeconomic Impacts ◽  
Climate Simulations ◽  
Urban Heat

AbstractUrban heat waves (UHWs) are strongly associated with socioeconomic impacts. Here, we use an urban climate emulator combined with large ensemble global climate simulations to show that, at the urban scale a large proportion of the variability results from the model structural uncertainty in projecting UHWs in the coming decades under climate change. Omission of this uncertainty would considerably underestimate the risk of UHW. Results show that, for cities in four high-stake regions – the Great Lakes of North America, Southern Europe, Central India, and North China – a virtually unlikely (0.01% probability) UHW projected by single-model ensembles is estimated by our model with probabilities of 23.73%, 4.24%, 1.56%, and 14.76% respectively in 2061–2070 under a high-emission scenario. Our findings suggest that for urban-scale extremes, policymakers and stakeholders will have to plan for larger uncertainties than what a single model predicts if decisions are informed based on urban climate simulations.

scholarly journals Using ENVI-met simulation to analyze heat island intensity in megalopolises

Vestnik MGSU ◽  
2020 ◽  
pp. 1262-1273
Author(s):  
Le Minh Tuan ◽  
Ilkhomzhon S. Shukurov ◽  
Margarita О. Gelmanova ◽  
Mikhail Yu. Slesarev
Keyword(s):  
Air Temperature ◽  
Simulation Analysis ◽  
Urban Climate ◽  
Construction Materials ◽  
Urban Morphology ◽  
Urban Environments ◽  
Urban Heat Islands ◽  
Heat Island ◽  
Urban Heat ◽  
Urban Microclimates

Introduction. The simulation of urban microclimates, including the urban heat island (UHI) phenomenon, has turned all the more important for urban planning. Presently, the analysis of this phenomenon is feasible thanks to high computational power of computers and links between computer modeling instruments and databases that contain information on urban environments. Advanced hardware helps to study characteristics of urban microclimates by analyzing and assessing their exposure to various climatic and anthropogenic urban factors (urban morphology, land use, construction sites, albedo, etc.) Materials and methods. ENVI-met is a software model used to simulate microclimates in urban environments. This software can optimize proportions of buildings and streets, outdoor shading, outdoor space planning, air movement, and use of construction materials in respect of thermal comfort and measures taken to mitigate consequences of urban heat islands within the framework of environmental planning of new districts. The co-authors analyze Ha Dong, a Hanoi district characterized by the high density of high-rise buildings. The co-authors consider the example of this district to study the process of detailed simulation, analysis and assessment of UHI effects. Results. ENVI-met and its simulation capacity is employed to prove that the air temperature in Wang Fu, an urban area, gradually rises from 8 am to 5 pm, when the air temperature reaches its maximal value of 32.28 °C during the period of sixteen hours. UHI intensity was maximal between midnight and 1 am on May 29, 2017, when it reached 2.41 °C. Conclusions. Cities are complex systems exposed to a wide array of interactive factors that influence the urban climate change. The value of R2 equal to 0.94 has proven the reliability of ENVI-met applied to simulate and imitate the climate of Hanoi, which is a hot and damp tropical city.

Measuring night-time urban heat island. Still a pending issue

2020 ◽  
Author(s):  
Josep Roca ◽  
Blanca Arellano
Keyword(s):  
Urban Heat Island ◽  
Land Surface ◽  
Heat Waves ◽  
Heat Island ◽  
Night Time ◽  
Structural Problems ◽  
First Case ◽  
Urban Heat ◽  
Weather Stations ◽  
Land Covers

<p>The study of urban heat island (UHI) is of great relevance in the context of climate change (CC) and global warming. Cities accumulate heat in urban land covers as well as in built infrastructures, representing true islands of heat in relation to their rural environment, less urbanized. The literature on urban climate has highlighted the singular importance of night UHI phenomenon. It is during the night that the effects of UHI become more apparent, due to the low cooling capacity of urban construction materials and is during nighttime that temperatures can cause higher health risks, leading to the aggravation of negative impacts on people’s health and comfort in extreme events such as heat waves becoming more and more frequent and lasting longer. However, the study of nocturnal UHIs is still poorly developed, due to the structural problems regarding the availability of land surface and air temperature data for night time.</p><p>Traditional methods for obtaining nocturnal UHI have been directed either to extrapolation of data from weather stations, or obtaining air temperatures through urban transects. In the first case, the lack of weather stations in urban landscapes makes it extremely difficult to obtain data to extrapolate and propose models at a detailed resolution scale. In the second case, there is a manifest difficulty in obtaining data simultaneously and significantly representative of urban and rural zones. Another used methodology for measuring the nocturnal UHI is remote sensing from MODIS images, but the greatest limitation about this method is the low resolution, therefore it is clear the need for open source databases with better or higher resolution to quantify the night surface temperature.</p><p>This paper aims to develop a model for nocturnal UHI analysing several areas of Alta and Baja California as well as in the Mediterranean Coast, using data from the Landsat thermal bands (with an spatial resolution of 30 square meters per pixel) and contrasting Landsat's very limited nighttime images with daytime ones. The contrast allows the construction of “cooling” models of the LST based on geographical characteristics (longitude, latitude, distance to the sea, DTM, slope, orientation, etc.) and urban-spatial parameters (land uses and land covers), which are likely to be extrapolated to different time periods.</p>

Urban resilience to future urban heat waves under a climate change scenario: A case study for Porto urban area (Portugal)

Urban Climate ◽  
2017 ◽  
Vol 19 ◽  
pp. 1-27 ◽  
Author(s):  
D. Carvalho ◽  
H. Martins ◽  
M. Marta-Almeida ◽  
A. Rocha ◽  
C. Borrego
Keyword(s):  
Climate Change ◽  
Urban Area ◽  
Climate Change Scenario ◽  
Heat Waves ◽  
Change Scenario ◽  
Urban Resilience ◽  
Urban Heat

100 Years of Climate Change: A Night-Time Audio Walk

Leonardo ◽  
2011 ◽  
Vol 44 (1) ◽  
pp. 68-69
Author(s):  
Drew Hemment ◽  
Yara El-Sherbini ◽  
Carlo Buontempo ◽  
John Tweddle
Keyword(s):  
Climate Change ◽  
Urban Heat Island ◽  
Urban Climate ◽  
Urban Heat Island Effect ◽  
Heat Island ◽  
Night Time ◽  
Island Effect ◽  
Urban Heat ◽  
Local Impacts ◽  
Short Walk

100 Years of Climate Change is an artwork inspired by the insight that we might experience 100 years of climate change by taking a short walk of 100 metres. Investigation of the local impacts of the Urban Heat Island effect culminated in a night-time audio walk to open up awareness of the urban climate.

scholarly journals Impact of drought conditions on urban climate of Zagreb (Croatia)

2021 ◽  
Author(s):  
Irena Nimac ◽  
Ivana Herceg-Bulić ◽  
Maja Žuvela-Aloise ◽  
Matej Žgela
Keyword(s):  
Air Temperature ◽  
Heat Load ◽  
Heat Waves ◽  
Urban Climate ◽  
Late Winter ◽  
Landsat 8 ◽  
Climate Effect ◽  
Spring Period ◽  
Drought Conditions ◽  
Urban Heat

<p>Dry periods and heat waves are becoming more frequent and intense in changing climate. Effect and impact of such specific events on local climate and ecosystems may vary spatially. One of the critical spots regarding extreme warm events are urban areas due to increased heat load. Here, we examine impact of drought conditions on characteristics of summertime urban heat island (UHI) for Zagreb, Croatia. For these purposes daily air temperature, precipitation, relative humidity, wind speed and wind direction data from the station Zagreb-Maksimir in a period 1928–2019 are used in the analysis. To define dry and wet conditions, standardized precipitation evapotranspiration index (SPEI) is used. The effect of drought conditions on summer UHI is analyzed from the perspective of preceding (i.e. wintertime and springtime) as well as concurrent (i.e. summertime) drought conditions. To estimate urban heat load in the city, urban climate model MUKLIMO_3 combined with cuboid method is used. Urban heat load is here represented as a number of summer days, i.e. days with maximum air temperature above 25°C. Landsat-8 satellite data were employed to analyze land surface temperature for specific situations. Results indicated substantial increase in heat load for situations when dry summer was preceded by dry late winter-spring period. However, when late winter-spring period was wet and followed with dry summer, much weaker increase in heat load is obtained. On the other hand, decrease in heat load is found for wet summer preceded by wet late winter-spring season. It is also showed that intensity of UHI is affected with drought conditions.</p><p> </p>

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