Quantitative city ventilation evaluation for urban canopy under heat island circulation without geostrophic winds: Multi-scale CFD model and parametric investigations

2021 ◽  
pp. 107793
Author(s):  
Yi Jing ◽  
Huai-Yu Zhong ◽  
Wei-Wei Wang ◽  
Yi He ◽  
Fu-Yun Zhao ◽  
...  
Keyword(s):  
Urban Canopy ◽  
Heat Island ◽  
Cfd Model ◽  
Multi Scale

Visualization of the missing role of hydrothermal interactions in a Japanese megalopolis for a win–win solution

2012 ◽  
Vol 66 (2) ◽  
pp. 409-414 ◽  
Author(s):  
T. Nakayama
Keyword(s):  
Urban Canopy ◽  
Feedback Mechanism ◽  
Hydrologic Cycle ◽  
Heat Island ◽  
Multi Scale ◽  
Island Effect ◽  
Urban Geometry ◽  
Hydrologic Change ◽  
Urban Heat

The urban heat island effect has become a serious environmental problem with the expansion of cities and industrial areas. Prohibition of the use of groundwater has caused a further serious problem such as floating of subways, stations and buildings through an imbalance of the hydrologic cycle in a Japanese megalopolis. Most of the previous research has evaluated separately hydrologic and thermal cycles in atmospheric, land and water areas because of the complexity in this feedback mechanism. In this study, the author used the process-based National Integrated Catchment-based Eco-hydrology (NICE) model, which includes surface–unsaturated–saturated water processes coupled with the urban canopy and regional atmospheric models, to simulate the effect of urban geometry and anthropogenic exhaustion on the hydrothermal changes in the atmospheric/land areas of the Japanese megalopolis. The simulation was conducted with multi-scale in horizontal regional–urban-point levels and in vertical atmosphere–surface–unsaturated–saturated layers, and projected the effect of water resources use to ameliorate the heat island and its impact on the hydrologic change in the catchment. Finally, the author presented the procedure to visualize the missing role of hydrothermal interactions in atmospheric, land and water areas, which would be effective to recover a sound hydrologic cycle and to create thermally pleasing environments in an eco-conscious megalopolis.

Multi-Scale 3D Geovisualization of Urban Heat Island Data for Planning Dialogue in Toronto

2015 ◽  
pp. 166-187
Author(s):  
John Danahy ◽  
Jacob Mitchell ◽  
Robert Wright ◽  
Rodney Hoinkes ◽  
Rob Feick
Keyword(s):  
Urban Heat Island ◽  
Analytical Models ◽  
Heat Island ◽  
Climate Change Effects ◽  
Multi Scale ◽  
Extreme Heat Events ◽  
Urban Models ◽  
Planning Decision ◽  
Urban Heat ◽  
Policies And Programs

This e-planning visualization case study in the Toronto region investigated the use of 3D urban models as a visualization reference against which analytical models were visualized to identify micro-scale mitigation scenarios of urban heat island effects. The case studies were directed to processes of planning decision making. The Toronto region faces problems of urban heat island impacts due to the increasing frequency of extreme heat events (Bass, Krayenhoff, & Martilli, 2002). The City of Toronto and the Toronto and Region Conservation Authority (TRCA) have each implemented policies and programmes aimed at mitigating urban heat island and climate change effects (City of Toronto, 2006). This research explored ways of visualizing remote sensing heat island data to assist with the targeted application of planning policies and programs.

Multi-Scale 3D Geovisualization of Urban Heat Island Data for Planning Dialogue in Toronto

2017 ◽  
pp. 570-591
Author(s):  
John Danahy ◽  
Jacob Mitchell ◽  
Robert Wright ◽  
Rodney Hoinkes ◽  
Rob Feick
Keyword(s):  
Urban Heat Island ◽  
Analytical Models ◽  
Heat Island ◽  
Climate Change Effects ◽  
Multi Scale ◽  
Extreme Heat Events ◽  
Urban Models ◽  
Planning Decision ◽  
Urban Heat ◽  
Policies And Programs

This e-planning visualization case study in the Toronto region investigated the use of 3D urban models as a visualization reference against which analytical models were visualized to identify micro-scale mitigation scenarios of urban heat island effects. The case studies were directed to processes of planning decision making. The Toronto region faces problems of urban heat island impacts due to the increasing frequency of extreme heat events (Bass, Krayenhoff, & Martilli, 2002). The City of Toronto and the Toronto and Region Conservation Authority (TRCA) have each implemented policies and programmes aimed at mitigating urban heat island and climate change effects (City of Toronto, 2006). This research explored ways of visualizing remote sensing heat island data to assist with the targeted application of planning policies and programs.

A Scaling Law for the Urban Heat Island Phenomenon: Deductions From Field Measurements and Comparisons With Existing Results From Laboratory Experiments

2014 ◽  
Author(s):  
Marina K.-A. Neophytou ◽  
Harindra J. S. Fernando ◽  
Ekaterina Batchvarova ◽  
Mats Sandberg ◽  
Jos Lelieveld ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Laboratory Experiments ◽  
Scaling Law ◽  
Field Measurements ◽  
Capital City ◽  
Mitigation Measures ◽  
Heat Island ◽  
Multi Scale ◽  
Urban Heat ◽  
The Impact

We report results from a multi-scale field experiment conducted in Cyprus in July 2010 in order to investigate the Urban Heat Island (UHI) in Nicosia capital city and its interaction with multi-scale meteorological phenomena taking place in the broader region. Specifically, the results are analysed and interpreted in terms of a non-dimensional/scaling parameter dictating the urban heat island circulation reported from laboratory experiments (Fernando et al, 2010). We find that the field measurements obey the same scaling law during the day, in the absence of any other flow phenomena apart from the urban heating. During the night we find that the deduced non-dimensional value reduces to half (compared to that during the day); this is due to the presence of katabatic winds from Troodos mountains into the urban center of Nicosia and their cooling effect superimposed on diurnal urban heating. Based on this deduction, the impact of various proposed heat island mitigation measures in urban planning can be evaluated.

scholarly journals Advantages of using a fast urban boundary layer model as compared to a full mesoscale model to simulate the urban heat island of Barcelona

2016 ◽  
Vol 9 (12) ◽  
pp. 4439-4450 ◽  
Author(s):  
Markel García-Díez ◽  
Dirk Lauwaet ◽  
Hans Hooyberghs ◽  
Joan Ballester ◽  
Koen De Ridder ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Simple Model ◽  
Wind Speed ◽  
Mesoscale Model ◽  
Urban Climate ◽  
Urban Canopy ◽  
Forecast Model ◽  
Heat Island ◽  
Layer Model ◽  
Urban Heat

Abstract. As most of the population lives in urban environments, the simulation of the urban climate has become a key problem in the framework of the climate change impact assessment. However, the high computational power required by high-resolution (sub-kilometre) fully coupled land–atmosphere simulations using urban canopy parameterisations is a severe limitation. Here we present a study on the performance of UrbClim, an urban boundary layer model designed to be several orders of magnitude faster than a full-fledged mesoscale model. The simulations are evaluated with station data and land surface temperature observations from satellites, focusing on the urban heat island (UHI). To explore the advantages of using a simple model like UrbClim, the results are compared with a simulation carried out with a state-of-the-art mesoscale model, the Weather Research and Forecasting Model, which includes an urban canopy model. This comparison is performed with driving data from ERA-Interim reanalysis (70 km). In addition, the effect of using driving data from a higher-resolution forecast model (15 km) is explored in the case of UrbClim. The results show that the performance of reproducing the average UHI in the simple model is generally comparable to the one in the mesoscale model when driven with reanalysis data (70 km). However, the simple model needs higher-resolution data from the forecast model (15 km) to correctly reproduce the variability of the UHI at a daily scale, which is related to the wind speed. This lack of accuracy in reproducing the wind speed, especially the sea-breeze daily cycle, which is strong in Barcelona, also causes a warm bias in the reanalysis driven UrbClim run. We conclude that medium-complexity models as UrbClim are a suitable tool to simulate the urban climate, but that they are sensitive to the ability of the input data to represent the local wind regime. UrbClim is a well suited model for impact and adaptation studies at city scale without high computing requirements, but does not replace the need for mesoscale atmospheric models when the focus is on the two-way interactions between the city and the atmosphere.

scholarly journals Modified RAMS-Urban Canopy Model for Heat Island Simulation in Chongqing, China

2008 ◽  
Vol 47 (2) ◽  
pp. 509-524 ◽  
Author(s):  
Hongbin Zhang ◽  
Naoki Sato ◽  
Takeki Izumi ◽  
Keisuke Hanaki ◽  
Toshiya Aramaki
Keyword(s):  
Urban Canopy ◽  
Heat Emission ◽  
Atmospheric Modeling ◽  
Anthropogenic Heat ◽  
Urban Region ◽  
Infinite Length ◽  
Heat Island ◽  
Urban Canopy Model ◽  
Canopy Model ◽  
Anthropogenic Heat Emission

Abstract A single-layer urban canopy model was integrated into a nonhydrostatic meteorological model, the Regional Atmospheric Modeling System (RAMS). In the new model, called RAMS-Urban Canopy (RAMS-UC), anthropogenic heat emission was also considered. The model can be used to calculate radiation, heat, and water fluxes in an urban area, considering the geometric structure and thermodynamic characteristics of the urban canopy. The urban canopy was represented by normalized street canyons of infinite length, which were bordered by buildings on both sides. The urban region was covered by three types of surfaces: roof, wall, and road. Anthropogenic heat was emitted from these surfaces. Sensitivity tests between the original RAMS and the modified one were carried out by simulating the urban heat island (UHI) of Chongqing, located in an inland mountainous region in China. The results of the model were also compared with the observational data. It was found that the original model could not accurately simulate the UHI, in particular at night, whereas the accuracy was significantly improved in the RAMS-UC. The improvement is substantial even when anthropogenic heat emission is set to zero.

scholarly journals A tree-planting decision support tool for urban heat island mitigation

2019 ◽  
Author(s):  
Zoey Werbin ◽  
Leila Heidari ◽  
Sarabeth Buckley ◽  
Paige Brochu ◽  
Lindsey Butler ◽  
...  
Keyword(s):  
Urban Heat Island ◽  
Web Application ◽  
Tree Mortality ◽  
Urban Canopy ◽  
Urban Trees ◽  
Tree Planting ◽  
Heat Island ◽  
Support Tool ◽  
Mortality And Morbidity ◽  
Urban Heat

AbstractHeat poses an urgent threat to public health in cities, as the urban heat island (UHI) effect can amplify exposures, contributing to high heat-related mortality and morbidity. Urban trees have the potential to mitigate by providing substantial cooling, as well as co-benefits such as reductions in energy consumption. The City of Boston has attempted to expand its urban canopy, yet maintenance costs and high tree mortality have hindered successful canopy expansion. Here, we present an interactive web application called “Right Place, Right Tree - Boston” that aims to support informed decision-making for planting new trees. To highlight priority regions for canopy expansion, we developed a Boston-specific Heat Vulnerability Index (HVI) and present this alongside maps of summer temperatures. We also provide information about tree pests and diseases, suitability of species for various conditions, land ownership, maintenance tips, and alternatives to tree planting.

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