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While the crucial roles of ozone (O3) transport in the planetary boundary layer (PBL) have been acknowledged for some time, there is currently limited knowledge about this aspect primarily due to the limited availability of measurements to determine the characteristics of the PBL. In this study, measurements from a wind Light Detection and Ranging (LiDAR) system were taken to monitor vertical profile of wind pattern at an urban site in Hong Kong in September 2022, a period when the city was frequently impacted by tropical cyclones and experienced severe O3 pollution levels. The PBL height was identified based on the vertical profile of wind speed shear. By combining information on the PBL height, vertical wind profile, and O3 concentration, we performed a cross-sectional analysis to explore the total horizontal flux (THF) of O3 across the PBL in Hong Kong. Throughout the entire study month, the THF of O3 exhibited a predominant easterly component. However, during the O3 pollution episodes, the THF of O3 exhibited a predominant westerly component, indicating an increased regional transport from Greater Bay Area (GBA). The westerly winds between 240° and 300° contributed 61.2% to the total flux of O3 in the PBL during these episodes. In addition, clockwise veering winds were observed from the ground to the top of the PBL, which can be attributed to the Ekman spiral. As a result, during the O3 pollution episodes, the wind with the peak O3 flux shifted from westerly to northwesterly as the height increased in the PBL. The northwesterly THF of O3 between 290° and 300° reached its peak at 600 m above ground level during these episodes. These findings enhance our understanding of the 3D pollutant transports for both long-term averages and short-term pollution episodes in the GBA and Hong Kong. © 2023 Elsevier Ltd

Poor air quality has been a major urban environmental issue in large high-density cities all over the world, and particularly in Asia, where the multiscale complex of pollution dispersal creates a high-level spatial variability of exposure level. Investigating such multiscale complexity and fine-scale spatial variability is challenging. In this study, we aim to tackle the challenge by focusing on PM2.5 (particulate matter with an aerodynamic diameter less than 2.5 um,) which is one of the most concerning air pollutants. We use the widely adopted land use regression (LUR) modeling technique as the fundamental method to integrate air quality data, satellite data, meteorological data, and spatial data from multiple sources. Unlike most LUR and Aerosol Optical Depth (AOD)-PM2.5 studies, the modeling process was conducted independently at city and neighborhood scales. Correspondingly, predictor variables at the two scales were treated separately. At the city scale, the model developed in the present study obtains better prediction performance in the AOD-PM2.5 relationship when compared with previous studies (R2 from 0.72 to 0.80). At the neighborhood scale, point-based building morphological indices and road network centrality metrics were found to be fit-for-purpose indicators of PM2.5 spatial estimation. The resultant PM2.5 map was produced by combining the models from the two scales, which offers a geospatial estimation of small-scale intraurban variability. © 2021 by the authors.

The high-density urban boundary layer (UBL) is one of the most complex atmospheric conditions, while the field data of UBL is limited due to the lack of suitable measurement methods. To better understand the UBL structures in high-density cities, a pioneering investigation is conducted in Hong Kong by Doppler wind LiDAR. Vertical wind speed profiles are measured at three locations: Cape D'Aguilar (upwind), University of Hong Kong (downtown), and Hong Kong University of Science and Technology (downwind). To address the weak wind conditions in summer, the prevailing southwest wind condition is selected as the subject of investigation. Based on the observations, the gradient height over Hong Kong is approximately 1.0–1.2 km. Below this height, the vertical wind speed profiles are significantly modified by surface morphologies. The power-law equation appropriately parametrizes the upwind (α = 0.1–0.15) and downwind (α = 0.27) profiles, but it has limitations when parametrizing the downtown profile. Deficiencies of the vertical wind speed profiles predicted by conventional meso-scale simulations and wind-tunnel experiments are revealed. These results provide researchers and engineers benchmarking data to refine their urban climate predictions. They generalize a better understanding of the UBL climates, which can be shared with other high-density cities. © 2021 Elsevier B.V.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Computational fluid dynamics (CFD) is a mature method in wind engineering studies, but many air ventilation assessment (AVA) reports prepared by consulting firms in Hong Kong still suffer from the use of inappropriate techniques and computational settings in the CFD modeling stage. The main reason behind this is the lack of informative guidelines relating to CFD model settings in the AVA Technical Circular issued by local authorities. Other aspects of AVA that require improvement include terrain modeling techniques and understanding the sensitivity of modeled topographical size to the wind environment. This paper revisits and summarizes important aspects of current best-practice guidelines for robust CFD simulations. The study compares two conventional approaches to terrain treatment through a series of sensitivity tests. The first approach uses terrain features to cover the entire ground of the computational domain, whereas the second imitates wind tunnel experiments in which the domain includes an inclined buffer area. One drawback of the first approach was found to be the occurrence of numerical divergence when the terrain size is small; meanwhile, in the latter approach, the inclination angle of the buffer area must not exceed 30° to achieve robust results. The final stage of the study validates the results of CFD simulations based on the two approaches with experimental data from a dense city. The approach that mimics wind tunnel experiments with a buffer zone was found to achieve better correlations, and smaller normalized mean square errors with respect to the experimental data and is thus considered superior. © 2019 Elsevier Ltd

People's subjective response to any thermal environment is commonly investigated by using rating scales describing the degree of thermal sensation, comfort, and acceptability. Subsequent analyses of results collected in this way rely on the assumption that specific distances between verbal anchors placed on the scale exist and that relationships between verbal anchors from different dimensions that are assessed (e.g. thermal sensation and comfort) do not change. Another inherent assumption is that such scales are independent of the context in which they are used (climate zone, season, etc.). Despite their use worldwide, there is indication that contextual differences influence the way the scales are perceived and therefore question the reliability of the scales’ interpretation. To address this issue, a large international collaborative questionnaire study was conducted in 26 countries, using 21 different languages, which led to a dataset of 8225 questionnaires. Results, analysed by means of robust statistical techniques, revealed that only a subset of the responses are in accordance with the mentioned assumptions. Significant differences appeared between groups of participants in their perception of the scales, both in relation to distances of the anchors and relationships between scales. It was also found that respondents’ interpretations of scales changed with contextual factors, such as climate, season, and language. These findings highlight the need to carefully consider context-dependent factors in interpreting and reporting results from thermal comfort studies or post-occupancy evaluations, as well as to revisit the use of rating scales and the analysis methods used in thermal comfort studies to improve their reliability.

People's subjective response to any thermal environment is commonly investigated by using rating scales describing the degree of thermal sensation, comfort, and acceptability. Subsequent analyses of results collected in this way rely on the assumption that specific distances between verbal anchors placed on the scale exist and that relationships between verbal anchors from different dimensions that are assessed (e.g. thermal sensation and comfort) do not change. Another inherent assumption is that such scales are independent of the context in which they are used (climate zone, season, etc.). Despite their use worldwide, there is indication that contextual differences influence the way the scales are perceived and therefore question the reliability of the scales’ interpretation. To address this issue, a large international collaborative questionnaire study was conducted in 26 countries, using 21 different languages, which led to a dataset of 8225 questionnaires. Results, analysed by means of robust statistical techniques, revealed that only a subset of the responses are in accordance with the mentioned assumptions. Significant differences appeared between groups of participants in their perception of the scales, both in relation to distances of the anchors and relationships between scales. It was also found that respondents’ interpretations of scales changed with contextual factors, such as climate, season, and language. These findings highlight the need to carefully consider context-dependent factors in interpreting and reporting results from thermal comfort studies or post-occupancy evaluations, as well as to revisit the use of rating scales and the analysis methods used in thermal comfort studies to improve their reliability.

Thermal discomfort is one of the main triggers for occupants interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses.

Thermal discomfort is one of the main triggers for occupants’ interactions with components of the built environment such as adjustments of thermostats and/or opening windows and strongly related to the energy use in buildings. Understanding causes for thermal (dis-)comfort is crucial for design and operation of any type of building. The assessment of human thermal perception through rating scales, for example in post-occupancy studies, has been applied for several decades; however, long-existing assumptions related to these rating scales had been questioned by several researchers. The aim of this study was to gain deeper knowledge on contextual influences on the interpretation of thermal perception scales and their verbal anchors by survey participants. A questionnaire was designed and consequently applied in 21 language versions. These surveys were conducted in 57 cities in 30 countries resulting in a dataset containing responses from 8225 participants. The database offers potential for further analysis in the areas of building design and operation, psycho-physical relationships between human perception and the built environment, and linguistic analyses.

This study presents a method for calculating solar irradiance of street canyons using Google Street View (GSV) images and investigates its spatiotemporal patterns in a high-density urban environment. In this method, GSV images provide a unique way to characterize the street morphology from which the diurnal solar path and solar radiation exposure can be estimated in a street canyon. Verifications of our developed method using free-horizon HKO observations and street-level field measurements show that both the calculated clear-sky and all-sky solar irradiance of street canyons well capture the diurnal and seasonal cycles. In the high-density urban areas of Hong Kong, we found that (1) the lowest monthly averaged solar irradiations in winter are 6.6 (December) and 4.6 (February) MJ/m2/day, and the highest values in summer are 17.3 (July) and 10.8 (June) MJ/m2/day for clear-sky and all-sky calculations, respectively; (2) The spatial variability of solar irradiation is closely related to sky view factor (SVF). In summer, the irradiation in a low-rise region (SVF≥0.7) on average is about three times that in a high-rise region (SVF≤0.3), and they differ by about five times in winter; (3) Street orientation has a significant impact on the solar radiation received in a high-density street canyon. In general, street canyons with West-East orientation receive higher solar irradiation during summer and lower during winter compared to those with South-North orientation. The generated maps of street-level solar irradiation may help researchers investigate the interactions between solar radiation, human health and urban thermal balance in high-density urban environments. Keywords: Solar radiation; Sky view factor; Street canyon; Google Street View; Deep learning; Hong Kong

View factors for sky, trees, and buildings are three important parameters of the urban outdoor environment that describe the geometrical relationship between different surfaces from the perspective of radiative energy transfer. This study develops an approach for accurately estimating sky view factor (SVF), tree view factor (TVF), and building view factor (BVF) of street canyons in the high-density urban environment of Hong Kong using publicly available Google Street View (GSV) images and a deep-learning algorithm for extraction of street features (sky, trees, and buildings). As a result, SVF, TVF, and BVF maps of street canyons are generated. Verification using reference data of hemispheric photography from field surveys in compact high-rise and low-rise areas shows that the GSV-based VF estimates have a satisfying agreement with the reference data (all with R2 > 0.95), suggesting the effectiveness and high accuracy of the developed method. This is the first reported use of hemispheric photography for direct verification in a GSV-based streetscape study. Furthermore, a comparison between GSV-based and 3D-GIS-based SVFs shows that the two SVF estimates are significantly correlated (R2 = 0.40, p < 0.01) and show better agreement in high-density areas. However, the latter overestimates SVF by 0.11 on average, and the differences between them are significantly correlated with street trees (R2 = 0.53): the more street trees, the larger the difference. This suggests that a lack of street trees in a 3D-GIS model of street environments is the dominant factor contributing to the large discrepancies between the two datasets. © 2018 Elsevier Ltd

Ventilation in cities is crucial for thewell being of their inhabitants. Therefore, local governments require air ventilation assessments (AVAs) prior to the construction of new buildings. In a standard AVA, however, only neutral stratification is considered, although diabatic and particularly unstable conditions may be observed more frequently in nature. The results presented here indicate significant changes in ventilation within most of the area of Kowloon City, Hong Kong, included in the study. A new definition for calculating ventilation was introduced, and used to compare the influence of buildings on ventilation under conditions of neutral and unstable stratification. The overall ventilation increased due to enhanced vertical mixing. In the vicinity of exposed buildings, however, ventilation was weaker for unstable stratification than for neutral stratification. The influence on ventilation by building parameters, such as the plan area index, was altered when unstable stratification was considered. Consequently, differences in stratification were shown to have marked effects on ventilation estimates, which should be taken into consideration in future AVAs.

Doctor of Psychology in Clinical Psychology, The nascent field of cultural psychology is rich with deconstructive elements and helpful perspectives, but it thus far has not produced many helpful clinical applications, particularly with how to conceptualize and treat polycultural persons in a tradition-sensitive way. The thesis of this case analysis is that working with clients out of a cultural psychology framework can be accomplished by working with the client's personal, familial, and cultural narratives. This means helping clients to order and build the histories that impact them in order to aid their construction a coherent self story. In the case of a polycultural individual, such a narrative analysis involves understanding how narrative themes from different sources (i.e., cultures) combine and affects the narrative identity of the individual. Therefore, treatment of individuals in this paradigm involves the co-construction of the client's self story by using as source material the perspectives of the narratives that meet in them.

In an urban planning context, an assessment indicator for evaluating a city's dispersion potential is beneficial, especially if the city has a complex natural terrain and significant wind variations. A study was conducted to implement an urban canopy drag indicator, taking site wind variation into account by involving both wind speed and direction in the calculations. Hong Kong (HK) was taken as an example due to its complicated natural topography and wind characteristics. A spatial distribution of an urban canopy drag over HK was determined based on wind data from 2004. The urban canopy drag values in three highly urbanized areas in HK, including Kowloon West, Kowloon East and Hong Kong Island North, were obtained and are discussed in detail. A fluid particle tracking program was developed and applied to identify the major wind paths in Kowloon West, with an area of approximately 5.5×6km as an example. We analyzed the diurnal variation in the dispersion times and the major wind paths in the region during both summer and winter. Our results estimated that the horizontal dispersion times of Kowloon West during both winter and summer were approximately 20min. By combining the wind paths from both seasons, we identified several major wind paths and critical ventilation areas in Kowloon West. This paper demonstrates the potential use of an urban canopy drag indicator for assessing air ventilation and pollutant dispersion in a city planning context. © 2014 Elsevier Ltd.

近幾十年來，全球氣候變化──特別是城市氣候變化──影響城市環境及居民生活質素的程度已引起公眾廣泛的討論。然而，過去研究一般採用之低空間解析度並不足夠為城市規劃及設計提供完善的資訊，引致對於氣候變化缺乏充分的考慮。高密度的城市環境（如香港）需要高時間解析度的氣候數據以制定有效的適應和減緩策略來應對未來氣候的變化。, 本研究採用線性迴歸技術，以預測未來香港市區和郊區的氣溫。本研究利用氣象站和統計延伸得出之基線氣溫數據來建立統計降尺度模型，以預測未來香港市區和郊區之平均氣溫、最高氣溫和最低氣溫。, 根據結果顯示，統計降尺度模型能夠有效建立大氣氣象參數和本港氣溫兩者之間的關係，尤其春季、秋季和冬季之氣溫預測表現理想。另外，冬季氣溫的上升趨勢則出現較大的升幅。研究結果亦顯示夜間氣溫的上升趨勢一般比日間為高。在未來的日子，郊區的溫度上升亦將會比市區為高。隨著城市化的影響納入預測溫度因素之中，預計郊區的氣溫將超過城市核心（天文台總部之氣象站），而郊區暖化的速度亦比市區和近郊為高。, 本研究發現統計降尺度方法能有助利用全球氣候模型（GCM）提供之數據，以預測未來氣候之變化。城市規劃與設計過程是需要大量的數據進行評估氣候變化對城市環境的影響之研究，儘管統計降尺度方法有一定程度的局限性，它仍然是一個低成本而有效的方法。根據未來預測之氣溫，本研究具體指出未來之氣候變化對於城市規劃和設計過程的影響，亦提出了一系列於不同規劃層面適用之適應和減緩措施的建議。, The effects of global climate change on urban environment have been widely discussed in recent decades. In particular, changes in urban climate have received much attention as they affect the living quality of urban dwellers. However, the coarse spatial scales employed in recent climate change studies were found to be insufficient in the context of urban planning and design. It leads to the lack of information on the changing urban climate and insufficient consideration of climate change in urban planning and design processes. In high-density cities like Hong Kong, the complex urban environment requires climatic data at very fine temporal resolution in order to formulate effective adaptation and mitigation strategies for future climate change., The present study employed regression techniques to establish empirical relationship between large-scale predictor variables and local predictands in order to obtain future air temperature of urban and rural areas of Hong Kong. 40-year baseline conditions of local air temperature were obtained from both the observational and statistically extended temperature record. Monthly means of daily mean, maximum, and minimum air temperatures for both daytime and night-time were calculated for establishing statistical downscaling (SD) models to project future air temperature of urban and rural areas of Hong Kong., The results suggest that regression-based downscaling techniques are able to capture the relationship between large-scale atmospheric conditions and station-scale meteorological parameters. The SD models performed particularly well in winter and considerably satisfactory results were obtained in spring and autumn. Night-time temperature trends generally exhibited greater increases than daytime trends. Seasonal variations were present with greatest increases observed in winter. Rural areas would likely experience greater warming than the urban areas in the future. With urbanization effect incorporated into the projected temperature series, it was found that air temperature projected for suburban stations would exceed that for the urban core. Rural warming also exhibited a higher rate than those observed in suburban and urban stations., The present study shows that statistical downscaling approach provides a method to obtain information about future climatic conditions at local scale by using GCM outputs which are widely accepted to be useful tools to assist climate change studies. Despite of the limitations that historical climate would persist in projected climatic series, it allows a low-cost but effective measure for climate impact assessments, particularly in the context of urban planning and design, which requires extensive data for a wide range of studies. Based on the projected air temperature, implications of future climate change on urban planning and design of potential development were discussed and recommendations on potential adaptation and mitigation measures at different planning levels were also presented., Detailed summary in vernacular field only., Lau, Ka Lun., Thesis (Ph.D.) Chinese University of Hong Kong, 2013., Includes bibliographical references (leaves 159-173)., s also in Chinese., http://library.cuhk.edu.hk/record=b6116181, Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/)

In this study, a high-resolution frontal area density (FAD) map that depicts the surface roughness of urban Hong Kong is produced using a mapping method that takes into account the dense urban morphology and the site wind availability of the territory. Using the MM5/CALMET model simulated wind data of Hong Kong, the FAD map of three urban zones are calculated: podium (0-15 m), building (15-60 m), and urban canopy (0-60 m). The wind tunnel test data is used to correlate the FAD understanding of the three zones. The grid sensitivity test indicates that 200m x 200m is the reasonable resolution for the FAD map; the test also establishes that the lower urban podium zone yields the best correlation with the experimental data. The study further establishes that the simpler two-dimensional ground coverage ratio (GCR), which is readily available in the planning circle, can be used to predict the area's average pedestrian level urban ventilation performance of the city. Working with their inhouse GIS team using available data, it allows the planners a way to understand the urban ventilation of the city for decisions related to air paths, urban permeability and site porosity. (C) 2011 Elsevier B.V. All rights reserved.

This project has added to knowledge in five main areas: It has mapped the range and types of policies and interventions that have been implemented in Canada, Denmark, Norway, Sweden and the UK that may influence employment chances for chronically ill and disabled people. By doing so it has added to understanding about what has actually been tried in each country and what might be considered in others. It has refined a typology of the focussed interventions that have been identified, based on the underlying programme logic of the intervention, which aids strategic thinking about national efforts to help chronically ill and disabled people into work. It has produced systematic reviews of the impact of the focussed interventions on the employment chances of chronically ill and disabled people and demonstrated the use of the typology in helping to interpret the results of the evaluations. The project’s empirical analyses of individual-level data have identified how chronically ill people from different socio-economic groups have fared in the labour markets of the five countries over the past two decades. It has then tested these findings against hypotheses about the impact of macro-level labour market policies on chronically ill people to provide insights into the influence of the policy context. The project has contributed to methodological development in evidence synthesis and the evaluation of natural policy experiments. By studying a small number of countries in great depth, we gained greater understanding of the policies and interventions that have been tried in these countries to help chronically ill and disabled people into work, against the backdrop of the wider labour market and macro-economic trends in those countries. We then integrated evidence from the wider policy context into the findings of systematic reviews of effectiveness of interventions, to advance interpretation of the natural policy experiments that have been implemented in these countries.

In this presentation a class of integration strategies are explored in between the two extremes of symbolic integration and numerical quadrature, which are, respectively, aimed at the computer generation of answers in the form of exact expressions and numerical values. The theoretical advances in symbolic integration are discussed first, as motivation to the following, then three major contexts of applications with attendant case studies are examined, and finally four possible types of strategies for approximate integration are explored., Presented at the MACSYMA User's Conference, 27-29 Jul 77, California Univ., Berkeley.

Presented at Mathematical Software II, a Conference Held at Purdue Univ., Lafayette, IN, 29-31 May 74.

The study investigated potentials of rice husk ash as a replacement for Ordinary Portland Cement in the production of Compressed Earth Block (CEB) with a view to reducing building construction cost and the embodied energy of the blocks in the context of Nigeria. Graded levels (i.e. 10, 20, 30 and 40%) of RHA replaced cement in the mix for CEB moulding. The results of X-ray diffraction showed that RHA contained 80% SiO2. Also, the results of the compressive strength, water absorption capacity, and bulk density testing indicated that low compressive strength, high water absorption capacity, and low bulk density exhibited by RHA-CEB make doubtful the suitability of RHA as a partial replacement for Ordinary Portland cement in the building construction in the wet regions. However, RHA could find useful application as a stabilizing agent in CEB rather than as a partial replacement of cement.

With the aim of reducing carbon emissions and increasing hygrothermal comfort, buildings across the UK are undergoing energy retrofits. With historic buildings, it is important that retrofit actions have a limited negative impact on the building’s fabric and cultural significance. Work to date in the UK has focused on the retrofit of historic solid masonry construction, with little research into the retrofit of historic timber-framed buildings. Changes to these buildings must be managed through the use of established conservation principles. However, where infill panels are beyond repair or have previously been substituted with inappropriate materials, there exists the potential to retrofit a material with a higher thermal performance. Nonetheless, it must be ensured that this retrofit does not create interstitial hygrothermal conditions that could threaten the survival of surrounding historic fabric. In this paper the authors present the hygrothermal simulation and physical monitoring of three different potential replacement infill panels. Results from Glaser calculations, WUFI® Pro and WUFI® 2D are compared to measured results of physical test panels mounted between two climate-controlled chambers. Whilst all three prediction methods successfully identified interstitial condensation where it was measured to occur, major discrepancies existed both between simulated and measured results, and between different simulation methods.