Mapping the urban microclimatic spatial distribution in a sub-tropical high-density urban environment

Shi, Yuan; Ren, Chao; Zheng, Yingsheng; Ng, Edward

doi:10.1080/00038628.2015.1105195

Cited by 33 publications

(16 citation statements)

References 28 publications

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“…Mapping of the spatial distribution requires relatively stable weather conditions during the entire measurement period; that is, temporal variation of the weather conditions should be insignificant [30]. This requirement has been fulfilled for the field measurements used in this study.…”

Section: Field Measurementsmentioning

confidence: 97%

Air ventilation assessment under unstable atmospheric stratification — A comparative study for Hong Kong

Wang

2018

Building and Environment

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A B S T R A C TIn most current air ventilation assessment (AVA) studies, a simple neutral assumption that does not consider thermal effects is adopted, particularly for numerical simulation practices. With statistics of daytime observations during summer in Hong Kong as an example, this study demonstrates that neutral atmospheric boundary conditions occur with a very low probability, which implies that current practices are indeed far away from reality. This study is devoted to addressing this knowledge gap by cross-comparisons of field measurements, wind tunnel tests, and large-eddy simulations (LES) under neutral and unstable conditions. It is found that LEScomputed velocity ratios under unstable conditions are in line with field measurements, while results of simulations under neutral conditions are close to those of wind tunnel tests. Enhanced vertical mixing due to surface heating produces improved ventilation performance in the unstable case. The neutral assumption tends to underestimate pedestrian-level velocity ratios compared to a diabatic condition; hence it is deemed conservative when it is adopted in AVA practices. Moreover, stronger wind direction variance under unstable conditions results in weaker correlation between velocity ratios and frontal area indices than neutral conditions, which implies that street orientations become less important in ventilation under unstable conditions.

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Section: Field Measurementsmentioning

confidence: 97%

Air ventilation assessment under unstable atmospheric stratification — A comparative study for Hong Kong

Wang

2018

Building and Environment

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“…Suffering from severe negative UHI effects, the annual UHI intensity in Hong Kong ranges between 2 • C to 4 • C (Siu & Hart, 2013). Several researchers endeavored to address this issue (Chan, 2011;Nichol, et al, 2009;Paulina, Poh-Chin, & Melissa, 2015;Shi,et al, 2015;Siu & Hart, 2013;Tan, Lau, & Ng, 2016;). Nichol, et al (Nichol, et al, 2009) used thermal satellite images combined with ‗in situ' ground data in order to examine models of heat island genesis and thus identify the main causes of UHI in Hong Kong.…”

Section: Hong Kongmentioning

confidence: 99%

“…Regression results indicated that, the solar radiation and greenery density were the most important factors with a negative association with UHI intensities in both seasons. Shi, Y., et al (2015) investigated the spatial distribution of microclimatic condition in Hong Kong. They measured air temperature, wind speed, relative humidity and globe temperature of 87 locations in two selected sites in a summer day as well as a winter day.…”

Section: Hong Kongmentioning

confidence: 99%

Urban heat island mitigation strategies: A state-of-the-art review on Kuala Lumpur, Singapore and Hong Kong

Aflaki

Mirnezhad

Ghaffarianhoseini

et al. 2017

Cities

302

120

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Observing the rapid urban expansions and numerous infrastructure developments in the East-Asian context, many cities are suffering the urban heat island (UHI) effect and its associated environmental and social challenges. Moreover, the lack of sufficient attention to the application of effective heat mitigation strategies in current urban development in these cities can drastically intensify the eventual impacts of UHI. Therefore, many governmental sectors and policy makers have been implementing operative solutions for cooling cities. Nevertheless, this study argues that in Kuala Lumpur, despite the growing attention to this matter, there is still a need for more rigorous consideration by the architecture, engineering and construction (AEC) professionals as well as more scholarly studies to reflect sustainable solutions to the UHI effect. As a result, today, some of the dense urban areas in Kuala Lumpur are characterized with the use of thermally massive building materials, urban surfaces with low albedo, complex urban morphology, waste heat, and low density of vegetation. On the other hand, recent studies demonstrate that there has been a rapidly increasing interest in studies related to UHI in other East Asian regions such as Singapore and Hong Kong. Hence, this study develops a comparative analysis to provide a state-of-the-art review of the recent attempts towards mitigating the UHI effect in Kuala Lumpur, Singapore, and Hong Kong. Among several available UHI mitigation strategies, this study is limited to the analysis of the environmental impacts of urban vegetation (green roofs, green facades, vertical greeneries and green pavements). Findings reveal that in general, urban greening can significantly mitigate the UHI intensity, both directly and indirectly, resulting in the decrease of global air temperature and mean radiant temperature up to 4 ˚C and 4.5 ˚C respectively. Overall, the study develops new practical guidelines, discusses the public benefits and elaborates on the future directions of UHI studies.

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“…CFD methods become more popular in modeling the microenvironment air pollution, but there are still uncertainties due to the limitation of either the turbulent models or the computational resources [ 50 ]. The geographical mapping methods (based on real measured data, as a cost-effective way) have been used to map the microclimatic spatial distribution in the high-density urban environment of Hong Kong [ 51 ]. The results show a reasonably good mapping accuracy with high practicability when dealing with the complicated built environment of Hong Kong.…”

Section: Methodsmentioning

confidence: 99%

Fine-Scale Spatial Variability of Pedestrian-Level Particulate Matters in Compact Urban Commercial Districts in Hong Kong

Shi

2017

IJERPH

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Particulate matters (PM) at the pedestrian level significantly raises the health impacts in the compact urban environment of Hong Kong. A detailed investigation of the fine-scale spatial variation of pedestrian-level PM is necessary to assess the health risk to pedestrians in the outdoor environment. However, the collection of PM data is difficult in the compact urban environment of Hong Kong due to the limited amount of roadside monitoring stations and the complicated urban context. In this study, we measured the fine-scale spatial variability of the PM in three of the most representative commercial districts of Hong Kong using a backpack outdoor environmental measuring unit. Based on the measurement data, 13 types of geospatial interpolation methods were examined for the spatial mapping of PM2.5 and PM10 with a group of building geometrical covariates. Geostatistical modelling was adopted as the basis of spatial interpolation of the PM. The results show that the original cokriging with the exponential kernel function provides the best performance in the PM mapping. Using the fine-scale building geometrical features as covariates slightly improves the interpolation performance. The study results also imply that the fine-scale, localized pollution emission sources heavily influence pedestrian exposure to PM.

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Mapping the urban microclimatic spatial distribution in a sub-tropical high-density urban environment

Cited by 33 publications

References 28 publications

Air ventilation assessment under unstable atmospheric stratification — A comparative study for Hong Kong

Air ventilation assessment under unstable atmospheric stratification — A comparative study for Hong Kong

Urban heat island mitigation strategies: A state-of-the-art review on Kuala Lumpur, Singapore and Hong Kong

Fine-Scale Spatial Variability of Pedestrian-Level Particulate Matters in Compact Urban Commercial Districts in Hong Kong

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