scholarly journals URBAN HEAT ISLAND MICRO-MAPPING VIA 3D CITY MODEL

2018 ◽  
Vol XLII-4/W10 ◽  
pp. 201-207 ◽  
Author(s):  
U. Ujang ◽  
S. Azri ◽  
M. Zahir ◽  
A. Abdul Rahman ◽  
T. L. Choon
Keyword(s):  
Solar Radiation ◽  
Urban Heat Island ◽  
Three Dimensional ◽  
Building Design ◽  
Development Planning ◽  
Heat Island ◽  
Sustainable Building ◽  
3D City Models ◽  
Urban Heat ◽  
City Models

<p><strong>Abstract.</strong> Urban Heat Island (UHI) phenomenon has been a topic of intense study over the past several years. However, to visualise UHI model is still an issue. Common visualisation of UHI by using digital thematic maps shows that it is hard to perceive its impacts especially in a sophisticated micro-area such as in urbanized cities. Moreover, different building façade’s material gives different UHI value. Therefore, there is a need in computing and visualising this phenomenon in three-dimensional (3D) perspectives. Recently, the development of 3D city modelling shows the potential of solving these gaps. This can be seen from the characteristics of 3D city models that are suitable in representing micro-areas (complex cities) for UHI studies. Based on this issue, this research aims to produce a 3D UHI model by using 3D city models as a tool for efficient and sustainable building design. The main objective is to produce a new approach in visualising UHI in 3D perspectives by instigating 3D city models. Thus, the UHI effect could be predicted precisely by calculating the building façades value. This research explores the 3D shadow analysis, 3D solar radiation and 3D orientation analysis in UHI modelling via 3D city models. From the analyses, the results show that the 3D city models are capable in presenting the solar radiation value for each building façade. Furthermore, this approach can be used to simulate future UHI analysis-prediction and advantageous for pre-development planning.</p>

scholarly journals Analysis of Urban Heat Island and Heat Waves Using Sentinel-3 Images: a Study of Andalusian Cities in Spain

2021 ◽  
Author(s):  
David Hidalgo García
Keyword(s):  
Solar Radiation ◽  
Urban Heat Island ◽  
Heat Wave ◽  
Land Surface ◽  
Heat Waves ◽  
Economic Cost ◽  
Heat Island ◽  
Multivariate Relationships ◽  
Urban Heat ◽  
Wave Conditions

Abstract At present, understanding the synergies between the Surface Urban Heat Island (SUHI) phenomenon and extreme climatic events entailing high mortality, i.e., heat waves, is a great challenge that must be faced to improve the quality of life in urban zones. The implementation of new mitigation and resilience measures in cities would serve to lessen the effects of heat waves and the economic cost they entail. In this research, the Land Surface Temperature (LST) and the SUHI were determined through Sentinel-3A and 3B images of the eight capitals of Andalusia (southern Spain) during the months of July and August of years 2019 and 2020. The objective was to determine possible synergies or interaction between the LST and SUHI, as well as between SUHI and heat waves, in a region classified as highly vulnerable to the effects of climate change. For each Andalusian city, the atmospheric variables of ambient temperature, solar radiation, wind speed and direction were obtained from stations of the Spanish State Meteorological Agency (AEMET); the data were quantified and classified both in periods of normal environmental conditions and during heat waves. By means of Data Panel statistical analysis, the multivariate relationships were derived, determining which ones statistically influence the SUHI during heat wave periods. The results indicate that the LST and the mean SUHI obtained are statistically interacted and intensify under heat wave conditions. The greatest increases in daytime temperatures were seen for Sentinel-3A in cities by the coast (LST = 3.90 °C, SUHI = 1.44 °C) and for Sentinel-3B in cities located inland (LST = 2.85 °C, SUHI = 0.52 °C). The existence of statistically significant positive relationships above 99% (p < 0.000) between the SUHI and solar radiation, and between the SUHI and the direction of the wind, intensified in periods of heat wave, could be verified. An increase in the urban area affected by the SUHI under heat wave conditions is reported. Graphical Abstract

scholarly journals THREE-DIMENSIONAL SIMULATION OF URBAN HEAT ISLAND

1985 ◽  
Vol 28 (235) ◽  
pp. 101-107 ◽  
Author(s):  
Takeo SAITOH ◽  
Kozo FUKUDA
Keyword(s):  
Urban Heat Island ◽  
Three Dimensional ◽  
Heat Island ◽  
Urban Heat ◽  
Dimensional Simulation

scholarly journals Potential for Application of Retroreflective Materials instead of Highly Reflective Materials for Urban Heat Island Mitigation

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jihui Yuan ◽  
Kazuo Emura ◽  
Craig Farnham
Keyword(s):  
Solar Radiation ◽  
Urban Heat Island ◽  
Air Conditioning ◽  
Green Roofs ◽  
Heat Sinks ◽  
Heat Island ◽  
Limited Effect ◽  
Building Envelopes ◽  
Urban Heat ◽  
Cool Roofs

Research on urban heat island (UHI) mitigation has been carried out globally. Several strategies have been proposed or developed to mitigate UHI, including highly reflective (HR) envelopes of buildings, green roofs, urban vegetation, shading, heat sinks, and air-conditioning efficiency. Among these techniques, HR envelopes have been extensively studied as an effective method to mitigate the UHI effect by reducing energy consumption. However, because most of HR materials are diffusive, HR envelopes applied to vertical surfaces can reflect both onto roads and nearby buildings. Additionally, HR roofs cannot reflect all incoming solar radiation to the sky if there are high buildings around it. Thus, HR materials applied as building envelopes have a limited effect against the solar contribution to the UHI. In order to solve this problem, retroreflective (RR) materials, which reflect the solar radiation back towards the source, have been studied and developed to be applied as building envelopes instead of HR materials. This paper summarizes several previous researches on HR envelopes and cool roofs and summarizes several current researches on RR materials. The potential for application of RR envelopes in cities is proposed with consideration of economic and environmental factors.

Cool Roofs vs Solar Systems

2016 ◽  
Vol 824 ◽  
pp. 779-785
Author(s):  
Dominika Kassai-Szoó ◽  
András Zöld
Keyword(s):  
Solar Radiation ◽  
Urban Heat Island ◽  
Urban Climate ◽  
Tall Buildings ◽  
Point Of View ◽  
Heat Island ◽  
Solar Systems ◽  
Negative Effect ◽  
Urban Heat ◽  
Cool Roofs

Well known problem of urban heat island is partly due to the albedo of traditional roofs. Mostexperts of urban climate are convinced that the intensity of urban heat island will be less if theroofs reflect as big part of the solar radiation as possible. Researchers have found or developedappropriate materials of low absorptance in the wavelength spectrum of solar radiation together with high emissivity in the long infrared interval. As a result, roof covering may have such extraparameters as metal roof painted with colored cool coating has 0.8 reflectance and 0.8 emittanceindex or single ply-membrane white (PVC) has 0.7 reflectance and 0.8 emittance index.No doubt taking into account the settlement as a whole cool roofs may decrease the intensity ofurban heat island however some local negative effect should not be forgotten. Approaching the citycenter it is typical that low rise and tall buildings are nearby. In some cases the same buildinghas high and low rise wings, from the point of view of geometry similar is the situation between thefacade and a canopy or a balcony. In this case the radiation reflect by the horizontal surfaceconsiderably increases the load on the facade, in this paper the relevant cases are analysed and thecalculated extra load and its consequences are evaluated.

scholarly journals Numerical Investigation on the Urban Heat Island Effect by Using a Porous Media Model

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4681
Author(s):  
Tingzhen Ming ◽  
Shengnan Lian ◽  
Yongjia Wu ◽  
Tianhao Shi ◽  
Chong Peng ◽  
...  
Keyword(s):  
Porous Media ◽  
Urban Heat Island ◽  
Three Dimensional ◽  
Anthropogenic Heat ◽  
Heat Island ◽  
Circular Structure ◽  
Porous Media Model ◽  
Urban Heat ◽  
Artificial Heat ◽  
The Impact

The urban heat island (UHI) effect resulted from urbanization as well as industrialization has become a major environmental problem. UHI effect aggravates global warming and endangers human health. Thus, mitigating the UHI effect has become a primary task to address these challenges. This paper verifies the feasibility of a three-dimensional turbulent porous media model. Using this model, the authors simulate the urban canopy wind-heat environment. The temperature and flow field over a city with a concentric circular structure are presented. The impact of three factors (i.e., anthropogenic heat, ambient crosswind speed, and porosity in the central area) on turbulent flow and heat transfer in the central business district of a simplified city model with a concentric circular structure were analyzed. It is found that the three-dimensional turbulent porous media model is suitable for estimating the UHI effect. The UHI effect could be mitigated by reducing the artificial heat and improving the porosity of the central city area.

A Theoretical and Numerical Study of Urban Heat Island–Induced Circulation and Convection

2008 ◽  
Vol 65 (6) ◽  
pp. 1859-1877 ◽  
Author(s):  
Ji-Young Han ◽  
Jong-Jin Baik
Keyword(s):  
Urban Heat Island ◽  
Gravity Wave ◽  
Vertical Velocity ◽  
Three Dimensional ◽  
Internal Gravity Wave ◽  
Three Dimensions ◽  
Heat Island ◽  
Upward Motion ◽  
Additional Dimension ◽  
Urban Heat

Abstract Urban heat island–induced circulation and convection in three dimensions are investigated theoretically and numerically in the context of the response of a stably stratified uniform flow to specified low-level heating that represents an urban heat island. In a linear, theoretical part of the investigation, an analytic solution for the perturbation vertical velocity in a three-dimensional, time-dependent, hydrostatic, nonrotating, inviscid, Boussinesq airflow system is obtained. The solution reveals a typical internal gravity wave field, including low-level upward motion downwind of the heating center. Precipitation enhancement observed downwind of urban areas may be partly due to this downwind upward motion. The comparison of two- and three-dimensional flow fields indicates that the dispersion of gravity wave energy into an additional dimension results in a faster approach to a quasi-steady state and a weaker quasi-steady flow well above the concentrated heating region in three dimensions. In a nonlinear, numerical modeling part of the investigation, extensive dry and moist simulations using a nonhydrostatic, compressible model with advanced physical parameterizations [Advanced Regional Prediction System (ARPS)] are performed. While the maximum perturbation vertical velocity in the linear internal gravity wave field exists in the downwind region close to the heating center, the maximum updraft in three-dimensional dry simulations propagates downwind and then becomes quasi stationary. In three-dimensional moist simulations, it is demonstrated that the downwind upward motion induced by an urban heat island can initiate moist convection and result in downwind precipitation. The cloud induced by the downwind upward motion grows rapidly to become deep convective clouds. Heavy rainfalls are localized in a region not far from the heating center by a convective precipitating system that is nearly stationary. The differences in results between two and three dimensions are explained by the presence of (moist) convergence in an additional dimension. The numerical simulation results indicate that the intensity and horizontal structure of the urban heat island affect those of circulation and convection and hence the distribution of surface precipitation.

scholarly journals Solar3D: An Open-Source Tool for Estimating Solar Radiation in Urban Environments

2020 ◽  
Vol 9 (9) ◽  
pp. 524
Author(s):  
Jianming Liang ◽  
Jianhua Gong ◽  
Xiuping Xie ◽  
Jun Sun
Keyword(s):  
Solar Radiation ◽  
Open Source ◽  
Large Scale ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Slope Aspect ◽  
Atmospheric Conditions ◽  
3D City Models ◽  
Grass Gis ◽  
City Models

Solar3D is an open-source software application designed to interactively calculate solar irradiation on three-dimensional (3D) surfaces in a virtual environment constructed with combinations of 3D-city models, digital elevation models (DEMs), digital surface models (DSMs) and feature layers. The GRASS GIS r.sun solar radiation model computes solar irradiation based on two-dimensional (2D) raster maps for a given day, latitude, surface and atmospheric conditions. With the increasing availability of 3D-city models and demand for solar energy, there is an urgent need for better tools to computes solar radiation directly with 3D-city models. Solar3D extends the GRASS GIS r.sun model from 2D to 3D by feeding the model with input, including surface slope, aspect and time-resolved shading, which is derived directly from the 3D scene using computer graphics techniques. To summarize, Solar3D offers several new features that—as a whole—distinguish this novel approach from existing 3D solar irradiation tools in the following ways. (1) Solar3D can consume massive heterogeneous 3D-city models, including massive 3D-city models such as oblique airborne photogrammetry-based 3D-city models (OAP3Ds or integrated meshes); (2) Solar3D can perform near real-time pointwise calculation for duration from daily to annual; (3) Solar3D can integrate and interactively explore large-scale heterogeneous geospatial data; (4) Solar3D can calculate solar irradiation at arbitrary surface positions including on rooftops, facades and the ground.

scholarly journals Solar3D: A 3D Extension of GRASS GIS r.sun for Estimating Solar Radiation in Urban Environments

2020 ◽  
Author(s):  
Jianming Liang ◽  
Jianhua Gong ◽  
Xiuping Xie ◽  
Jun Sun
Keyword(s):  
Solar Radiation ◽  
Large Scale ◽  
Three Dimensional ◽  
Urban Environments ◽  
Solar Irradiation ◽  
Slope Aspect ◽  
Atmospheric Conditions ◽  
3D City Models ◽  
Grass Gis ◽  
City Models

Solar3D is an open-source software application designed to interactively calculate solar irradiation at three-dimensional (3D) surfaces in a virtual environment constructed with combinations of 3D city models, digital elevation models (DEMs), digital surface models (DSMs) and feature layers. The GRASS GIS r.sun solar radiation model computes solar irradiation based on two-dimensional (2D) raster maps for given day, latitude, surface and atmospheric conditions. With the increasing availability of 3D city models and demand for solar energy, there is an urgent need for better tools to computes solar radiation directly with 3D city models. Solar3D extends GRASS GIS r.sun from 2D to 3D by feeding the model with input, including surface slope, aspect and time-resolved shading, that is derived directly from the 3D scene using computer graphics techniques. To summarize, Solar3D offers several new features which, as a whole, distinguish itself from existing 3D solar irradiation tools: (1) the ability to consume massive heterogeneous 3D city models, including massive 3D city models such as oblique airborne photogrammetry-based 3D city models (OAP3Ds or integrated meshes); (2) the ability to perform near real-time pointwise calculation for duration from daily to annual; (3) the ability to integrate and interactively explore large-scale heterogeneous geospatial data. (4) the ability to calculate solar irradiation at arbitrary surface positions including at rooftops, facades and the ground. Solar3D is publicly available at https://github.com/jian9695/Solar3D.

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