scholarly journals Study of Urban Heat Islands Using Different Urban Canopy Models and Identification Methods

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 521
Author(s):  
Rui Silva ◽  
Ana Cristina Carvalho ◽  
David Carvalho ◽  
Alfredo Rocha
Keyword(s):  
Land Use ◽  
Temperature Difference ◽  
Model Simulation ◽  
Urban Canopy ◽  
Near Surface ◽  
Local Method ◽  
Identification Methods ◽  
Classic Method ◽  
Urban Heat ◽  
The City

This work aims to compare the performance of the single‑(SLUCM) and multilayer (BEP-Building effect parameterization) urban canopy models (UCMs) coupled with the Weather Research and Forecasting model (WRF), along with the application of two urban heat island (UHI) identification methods. The identification methods are: (1) the “classic method”, based on the temperature difference between urban and rural areas; (2) the “local method” based on the temperature difference at each urban location when the model land use is considered urban, and when it is replaced by the dominant rural land use category of the urban surroundings. The study is performed as a case study for the city of Lisbon, Portugal, during the record-breaking August 2003 heatwave event. Two main differences were found in the UHI intensity (UHII) and spatial distribution between the identification methods: a reduction by half in the UHII during nighttime when using the local method; and a dipole signal in the daytime and nighttime UHI spatial pattern when using the classic method, associated with the sheltering effect provided by the high topography in the northern part of the city, that reduces the advective cooling in the lower areas under prevalent northern wind conditions. These results highlight the importance of using the local method in UHI modeling studies to fully isolate urban canopy and regional geographic contributions to the UHII and distribution. Considerable improvements were obtained in the near‑surface temperature representation by coupling WRF with the UCMs but better with SLUCM. The nighttime UHII over the most densely urbanized areas is lower in BEP, which can be linked to its larger nocturnal turbulent kinetic energy (TKE) near the surface and negative sensible heat (SH) fluxes. The latter may be associated with the lower surface skin temperature found in BEP, possibly owing to larger turbulent SH fluxes near the surface. Due to its higher urban TKE, BEP significantly overestimates the planetary boundary layer height compared with SLUCM and observations from soundings. The comparison with a previous study for the city of Lisbon shows that BEP model simulation results heavily rely on the number and distribution of vertical levels within the urban canopy.

scholarly journals Analysis of temporal and spatial variability of atmospheric CO<sub>2</sub> concentration within Paris from the GreenLITE™ laser imaging experiment

2019 ◽  
Vol 19 (22) ◽  
pp. 13809-13825 ◽  
Author(s):  
Jinghui Lian ◽  
François-Marie Bréon ◽  
Grégoire Broquet ◽  
T. Scott Zaccheo ◽  
Jeremy Dobler ◽  
...  
Keyword(s):  
Urban Canopy ◽  
Temporal Variations ◽  
Horizontal Resolution ◽  
Atmospheric Co2 ◽  
Laser Imaging ◽  
Near Surface ◽  
Co2 Concentrations ◽  
Temporal And Spatial ◽  
The City

Abstract. In 2015, the Greenhouse gas Laser Imaging Tomography Experiment (GreenLITE™) measurement system was deployed for a long-duration experiment in the center of Paris, France. The system measures near-surface atmospheric CO2 concentrations integrated along 30 horizontal chords ranging in length from 2.3 to 5.2 km and covering an area of 25 km2 over the complex urban environment. In this study, we use this observing system together with six conventional in situ point measurements and the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) and two urban canopy schemes (Urban Canopy Model – UCM; Building Effect Parameterization – BEP) at a horizontal resolution of 1 km to analyze the temporal and spatial variations in CO2 concentrations within the city of Paris and its vicinity for the 1-year period spanning December 2015 to November 2016. Such an analysis aims at supporting the development of CO2 atmospheric inversion systems at the city scale. Results show that both urban canopy schemes in the WRF-Chem model are capable of reproducing the seasonal cycle and most of the synoptic variations in the atmospheric CO2 point measurements over the suburban areas as well as the general corresponding spatial differences in CO2 concentration that span the urban area. However, within the city, there are larger discrepancies between the observations and the model results with very distinct features during winter and summer. During winter, the GreenLITE™ measurements clearly demonstrate that one urban canopy scheme (BEP) provides a much better description of temporal variations and horizontal differences in CO2 concentrations than the other (UCM) does. During summer, much larger CO2 horizontal differences are indicated by the GreenLITE™ system than both the in situ measurements and the model results, with systematic east–west variations.

scholarly journals Analysis of temporal and spatial variability of atmospheric CO<sub>2</sub> concentration within Paris from the GreenLITE<sup>TM</sup> laser imaging experiment

2019 ◽  
Author(s):  
Jinghui Lian ◽  
François-Marie Bréon ◽  
Grégoire Broquet ◽  
T. Scott Zaccheo ◽  
Jeremy Dobler ◽  
...  
Keyword(s):  
Urban Canopy ◽  
Temporal Variations ◽  
Horizontal Resolution ◽  
Atmospheric Co2 ◽  
Laser Imaging ◽  
Near Surface ◽  
Co2 Concentrations ◽  
Temporal And Spatial ◽  
The City

Abstract. In 2015, the Greenhouse gas Laser Imaging Tomography Experiment (GreenLITETM) measurement system was deployed for a long-duration experiment in the center of Paris, France. The system measures near-surface atmospheric CO2 concentrations integrated along 30 horizontal chords ranging in length from 2.3 km to 5.2 km and covering an area of 25 km2 over the complex urban environment. In this study, we use this observing system together with six conventional in-situ point measurements and the WRF-Chem model coupled with two urban canopy schemes (UCM, BEP) at a horizontal resolution of 1 km to analyze the temporal and spatial variations of CO2 concentrations within the Paris city and its vicinity for the 1-year period spanning December 2015 to November 2016. Such an analysis aims at supporting the development of CO2 atmospheric inversion systems at the city scale. Results show that both urban canopy schemes in the WRF-Chem model are capable of reproducing the seasonal cycle and most of the synoptic variations in the atmospheric CO2 point measurements over the suburban areas, as well as the general corresponding spatial differences in CO2 concentration that span the urban area. However, within the city, there are larger discrepancies between the observations and the model results with very distinct features during winter and summer. During winter, the GreenLITETM measurements clearly demonstrate that one urban canopy scheme (BEP) provides a much better description of temporal variations and horizontal differences in CO2 concentrations than the other (UCM) does. During summer, much larger CO2 horizontal differences are indicated by the GreenLITETM system than both the in-situ measurements and the model results, with systematic east-west variations.

Spatial Model of Green Open Space Needs for Mitigation of Urban Heat Island Phenomenon in Semarang

2019 ◽  
Author(s):  
Bandi Sasmito ◽  
Yudo Prasetyo ◽  
Nurhadi Bashit ◽  
Titis Ismayanti
Keyword(s):  
Urban Heat Island ◽  
Spatial Model ◽  
Open Space ◽  
Model Simulation ◽  
Land Use Changes ◽  
Heat Island ◽  
Air Temperatures ◽  
Urban Heat ◽  
Space Requirements ◽  
The City

Increasing population of the can be effect to an increase in space requirements. Fulfilling space needs means that what happens is a land use changes. green land becomes a need for development land and is the cause of the effect of rising air temperatures in cities. These changes are very important to studying for make plans on city. This study intends to examine the needs of Green Open Space spatially based on the phenomenon of increasing temperature in a location within the city compared to its surroundings or called Urban Heat Island (UHI). Remote Sensing is used to detect UHI spatially. This UHI location will be used as spatial modeling data to assess how large and where is need green space. The expected processing results are a spatial model simulation of the adequacy of Green Open Space requirements that will be a mitigation of the UHI phenomenon that is presented spatially in the form of thematic maps as one of the data that can be used as consideration in the city design planning of Semarang in the long term.

scholarly journals Sensitivity of Simulated Urban–Atmosphere Interactions in Oklahoma City to Urban Parameterization

2017 ◽  
Vol 56 (5) ◽  
pp. 1405-1430 ◽  
Author(s):  
Larissa J. Reames ◽  
David J. Stensrud
Keyword(s):  
Urban Areas ◽  
Urban Canopy ◽  
Oklahoma City ◽  
Surface Model ◽  
Urban Canopy Model ◽  
Near Surface ◽  
Modeling Studies ◽  
Suburban Cities ◽  
The City ◽  
Canopy Model

AbstractThe world’s population is increasingly concentrated in large urban areas. Many observational and modeling studies have explored how these large, population-dense cities modify local and mesoscale atmospheric phenomena. These modeling studies often use an urban canopy model to parameterize urban surfaces. However, it is unclear whether this approach is appropriate for more suburban cities, such as those found in the Great Plains. Thus, the Weather Research and Forecasting Model was run for a week over Oklahoma City, Oklahoma, and results were compared with observations. Overall, four configurations were examined. Two simulations used the Noah LSM, one with all urban areas removed (CTRL), and the other with urban areas parameterized by a modified Noah land surface model with three urban categories (LSMMOD). Additional simulations utilized a single-layer urban canopy model (SLUCM) either with default urban fraction values (SLUCM1) or with urban fractions taken from the National Land Cover Database (SLUCM2). Results from the three urban runs compared favorably to high-density temperature observations of the urban heat island. The SLUCM1 run was the most realistic, although the urban fractions applied were the least representative of Oklahoma City. All urban runs also produced a drier and deeper planetary boundary layer over the city. The prediction of near-surface winds was most problematic, with the two SLUCM runs unable to correctly reproduce reduced wind speeds over the city. The modified Noah LSM provided best overall agreement with observations and represents a reasonable option for simulating the urban effects of more-suburban cities.

scholarly journals MONITORING SPATIOTEMPORAL CHANGES OF HEAT ISLAND IN BABOL CITY DUE TO LAND USE CHANGES

2017 ◽  
Vol XLII-4/W4 ◽  
pp. 17-22 ◽  
Author(s):  
S. K. Alavi Panah ◽  
M. Kiavarz Mogaddam ◽  
M. Karimi Firozjaei
Keyword(s):  
Land Use ◽  
Surface Temperature ◽  
Urban Heat Island ◽  
Land Surface ◽  
Land Use Changes ◽  
Heat Island ◽  
Time Period ◽  
Urban Heat ◽  
The City ◽  
Very High

Urban heat island is one of the most vital environmental risks in urban areas. The advent of remote sensing technology provides better visibility due to the integrated view, low-cost, fast and effective way to study and monitor environmental and humanistic changes. The aim of this study is a spatiotemporal evaluation of land use changes and the heat island in the time period of 1985-2015 for the studied area in the city of Babol. For this purpose, multi-temporal Landsat images were used in this study. For calculating the land surface temperature (LST), single-channel and maximum likelihood algorithms were used, to classify Images. Therefore, land use changes and LST were examined, and thereby the relationship between land-use changes was analyzed with the normalized LST. By using the average and standard deviation of normalized thermal images, the area was divided into five temperature categories, inter alia, very low, low, medium, high and very high and then, the heat island changes in the studied time period were investigated. The results indicate that land use changes for built-up lands increased by 92%, and a noticeable decrease was observed for agricultural lands. The Built-up land changes trend has direct relation with the trend of normalized surface temperature changes. Low and very low-temperature categories which follow a decreasing trend, are related to lands far away from the city. Also, high and very high-temperature categories whose areas increase annually, are adjacent to the city center and exit ways of the town. The results emphasize on the importance of attention of urban planners and managers to the urban heat island as an environmental risk.

scholarly journals Analysis of the urban heat island in representative points of the city of Bayeux / PB

2018 ◽  
Vol 7 (6) ◽  
pp. 345
Author(s):  
Amanda Mayara Paulino Da Silva
Keyword(s):  
Land Use ◽  
Urban Heat Island ◽  
Thermal Field ◽  
Urban Climate ◽  
Urban Heat Islands ◽  
Heat Island ◽  
Thermal Discomfort ◽  
Heat Islands ◽  
Urban Heat ◽  
The City

Abstrat Urban growth has generated several socio-environmental problems and has altered the quality of life of people living in these environments. Due to the disorderly growth of cities and the various forms of urban land use and occupation, changes in the thermal field of these areas have occurred and caused the formation of urban heat islands and thermal discomfort in urban environments. Thus, the need to understand the formation of heat islands in these areas and the study of their causes and consequences grows. Given this context, the present work intends to study the urban climate of the city of Bayeux / PB, specifically the urban thermal field, and the formation of heat islands. For the accomplishment of the research, initially a bibliographical survey of the subject in question was made. Subsequently experimental points of meteorological data collection (temperature and relative air humidity) were defined in the metropolitan area of the city of João Pessoa, specifically in the municipality of Bayeux / PB. These points were defined based on the different types of land use and cover in the study area. The following experimental points were defined: a point in the center of the city of Bayeux / PB, another point on the banks of the BR230 direction Bayeux, and a reference point in a remnant of Atlantic forest. To obtain the urban heat island the reference point was used as a parameter of the climatic conditions of a natural environment. The data of temperature and relative humidity were collected through thermometers (HOBO U-10), which were placed on steel tripods (1.5 meters high) and monitored at uninterrupted intervals of 1 and 1 hour during the dry period and rainy region. The analysis of the data points to the formation of urban heat islands in the two periods evaluated in the city of Bayeux / PB, being the center of the city, the most critical area with the most intense heat islands. The vegetative cover played a predominant role in the climatic mitigation of the experimental samples as well as the presence of precipitation. The areas with impermeable soil cover presented the largest heat islands and contributed to the thermal discomfort of the study area. Keywords: Urban Climate, Thermodynamic Field, Urban Heat Island.

scholarly journals Assessment of Urban Heat Islands Based on the Relationship Between Land Surface Temperature and Land Use/Land Cover in Greater Doha

2020 ◽  
Author(s):  
Simil Amir Siddiqui
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Urban Heat Islands ◽  
Land Use Land Cover ◽  
Heat Islands ◽  
Urban Heat ◽  
The City

Urban heat islands (UHI) are areas with elevated temperatures occurring in cities compared to surrounding rural areas. This study realizes the lack of research regarding the trends of UHIs in desert countries and focuses on Doha. The research includes twelve months of two-time periods; 2000-2019. ArcGIS software was used to compute the land surface temperature (LST) of the city using Landsat images. Land use/land cover (LULC) maps were computed to show how the city has evolved in 19 years. 30 field samples were used to verify the accuracy of the LULC. Results showed UHI in Doha did not display similar pattern to that of cities in subtropical and temperate regions. Higher temperatures were prevalent in out-skirts comprising of barren and built-up areas with high population and no vegetation. Comparatively, the main downtown with artificially planted vegetation and shade from skyscrapers created cooler microclimates. The overall LST of greater Doha has increased by 0.7°C from 2000 to 2019. Furthermore %LULC of built up, vegetation, barren land, marsh land and water body were 29%, 4.5%, 58.6%, 2.8% and 5% in 2000 and 56.5 %, 8.2%, 33.2 %, 0% and 2.1% in 2019 respectively. Overall, there was an increase in built-up and vegetation decrease in water and barren areas and complete loss of marshland. Highest temperatures were recorded for marshland area in year 2000 and barren and built in year 2019. Transect profiles showed positive correlation between NDBI and LST and a negative correlation between NDVI and LST.

scholarly journals Variação Microclimática de Sítios Urbanos com Diferentes Níveis de Cobertura Vegetal Como Subsídio à Formação de Ilha de Calor

2020 ◽  
Vol 13 (07) ◽  
pp. 3254
Author(s):  
Pedro Hugo Oliveira Moreira ◽  
Alan Cavalcanti da Cunha ◽  
João De Athaydes Silva Júnior ◽  
Antonio Carlos Lola da Costa
Keyword(s):  
Land Use ◽  
Relative Humidity ◽  
Urban Heat Island ◽  
Urban Space ◽  
Vegetation Index ◽  
Data Series ◽  
Heat Island ◽  
Urban Heat ◽  
Meteorological Elements ◽  
The City

O objetivo da investigação é analisar variações espaciais e sazonais de elementos meteorológicos que evidenciam a formação e ocorrência do fenômeno da Ilha de Calor Urbana (ICU) na cidade de Macapá. A metodologia de estudo avaliou a evolução histórica da cobertura de vegetação e da malha urbana utilizando-se técnicas de geoprocessamento e de classificação supervisionada de Máxima Verossimilhança (MAXVER). Com este objetivo foram analisadas séries de dados contínuos coletados durante dez dias consecutivos nos períodos chuvoso (Abril/2018), Seco (Novembro/2018) e Transição (Junho/2019). Os elementos meteorológicos quantificados foram a umidade relativa do ar (UR) e a temperatura média do ar (T). Cinco estações semi-automáticas foram estrategicamente distribuídas ao longo de dois eixos de máximo prolongamento da zona urbana de Macapá, nos sentidos Nordeste-Sudoeste e Oeste-Leste. Os resultados indicaram significativa variação sazonal da Temperatura e da Umidade Relativa (p<0,05). Espacialmente, os resultados também foram significativos (p<0,05), sugerindo influência espaço-sazonal dos padrões de variabilidade de T e UR sobre ICU correlacionados com as taxas de uso e ocupação do solo. Assim, ICU mostrou-se significativamente dependente tanto do índice de vegetação (R2=0,47, p<0,05) quanto do índice de urbanização (R2=0,62, p<0,05). Conclui-se que a sazonalidade diária observada sugere existência do fenômeno da ilha de calor urbana, especialmente nas zonas central e sul da cidade, cujos índices inclusive têm sido confirmados por estudos similares. Os dados de sazonalidade dos elementos meteorológicos analisados, sua relação com o uso do solo, podem trazer elementos importantes para o debate sobre a formação da ICU nas cidades amazônicas. Microclimatic Variation in Urban Sites with Different Levels of Vegetable Cover as a Subsidy to the Formation of Heat Island A B S T R A C TThe objective of the investigation is to analyze spatial and seasonal variations of meteorological elements that evidence the formation and occurrence of the phenomenon of the Urban Heat Island (UHI) in the city of Macapá. The study methodology comprised the historical evolution of vegetation cover and urban space using geoprocessing techniques and supervised classification of Maximum Likelihood (MAXVER). With this objective, continuous data series collected during ten consecutive days in the rainy (April/2018), Dry (November/2018) and Intermediate (June/2019) periods were analyzed. The meteorological elements quantified were relative humidity (RH) and average air temperature (T). Five semi-automatic gauges were strategically distributed along two axes of maximum extension of the urban area of Macapá, in the Northeast-Southwest and West-East directions. The results indicated significant seasonal variation of Temperature and Relative Humidity (p<0.05). Spatially, the results were also significant (p<0.05), suggesting influence of T and RH variability patterns on UHI correlated with land use and occupation rates on. Thus, ICU was significantly dependent on both the vegetation index (R2=0.47, p<0.05) and the urbanization index (R2=0.62, p<0.05). We concluded that the daily seasonality observed suggests the existence of the phenomenon of the urban heat island, especially in the central and southern zones of the city, whose indices have even been confirmed by similar studies. The seasonality data of the meteorological elements analyzed, their relationship with land use, can bring important elements to the debate on the formation of ICU in Amazonian cities.Keywords: Meteorological element, vegetation, urbanization, urban heat island, Macapá.

scholarly journals Use of Cool Roofs and Vegetation to Mitigate Urban Heat and Improve Human Thermal Stress in Melbourne, Australia

2018 ◽  
Vol 57 (8) ◽  
pp. 1747-1764 ◽  
Author(s):  
Stephanie J. Jacobs ◽  
Ailie J. E. Gallant ◽  
Nigel J. Tapper ◽  
Dan Li
Keyword(s):  
Thermal Stress ◽  
Heat Wave ◽  
Urban Canopy ◽  
Vegetation Coverage ◽  
Cool Roof ◽  
Urban Heat ◽  
Nighttime Temperatures ◽  
Individual Strategies ◽  
Cool Roofs ◽  
The City

AbstractThe ability of cool roofs and vegetation to reduce urban temperatures and improve human thermal stress during heat wave conditions is investigated for the city of Melbourne, Australia. The Weather Research and Forecasting Model coupled to the Princeton Urban Canopy Model is employed to simulate 11 scenarios of cool roof uptake across the city, increased vegetation cover across the city, and a combination of these strategies. Cool roofs reduce urban temperatures during the day, and, if they are installed across enough rooftops, their cooling effect extends to the night. In contrast, increasing vegetation coverage reduces nighttime temperatures but results in minimal cooling during the hottest part of the day. The combination of cool roofs and increased vegetation scenarios creates the largest reduction in temperature throughout the heat wave, although the relationship between the combination scenarios is nonsynergistic. This means that the cooling occurring from the combination of both strategies is either larger or smaller than if the cooling from individual strategies were to be added together. The drier, lower-density western suburbs of Melbourne showed a greater cooling response to increased vegetation without enhancing human thermal stress due to the corresponding increase in humidity. The leafy medium-density eastern suburbs of Melbourne showed a greater cooling response to the installation of cool roofs. These results highlight that the optimal urban cooling strategies can be different across a single urban center.

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