scholarly journals Measurement report: Vehicle-based multi-lidar observational study of the effect of meteorological elements on the three-dimensional distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area

2022 ◽  
Vol 22 (1) ◽  
pp. 139-153
Author(s):  
Xinqi Xu ◽  
Jielan Xie ◽  
Yuman Li ◽  
Shengjie Miao ◽  
Shaojia Fan
Keyword(s):  
Boundary Layer ◽  
Hong Kong ◽  
Particulate Matter ◽  
Vertical Distribution ◽  
Three Dimensional ◽  
Single Layer ◽  
Bay Area ◽  
Dimensional Distribution ◽  
Meteorological Elements ◽  
Horizontal And Vertical Distribution

Abstract. The distribution of meteorological elements has always been an important factor in determining the horizontal and vertical distribution of particles in the atmosphere. To study the effect of meteorological elements on the three-dimensional distribution structure of particles, mobile vehicle lidar and fixed-location observations were collected in the western Guangdong–Hong Kong–Macao Greater Bay Area of China during September and October in 2019 and 2020. Vertical aerosol extinction coefficient, depolarization ratio, and wind and temperature profiles were measured using a micro pulse lidar, a Raman scattering lidar, and a Doppler wind profile lidar installed on a mobile monitoring vehicle. The mechanism of how wind and temperature in the boundary layer affects the horizontal and vertical distribution of particles was analysed. The results show that particles were mostly distributed in downstream areas on days with moderate wind speed in the boundary layer, whereas they were distributed homogeneously on days with weaker wind. There are three typical types of vertical distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area (GBA): surface single layer, elevated single layer, and double layer. Analysis of wind profiles and Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) backward trajectory reveals different sources of particles for the three types. Particles concentrating near the temperature inversion and multiple inversions could cause more than one peak in the extinction coefficient profile. There were two mechanisms affecting the distribution of particulate matter in the upper and lower boundary layers. Based on this observational study, a general model of meteorological elements affecting the vertical distribution of urban particulate matter is proposed.

scholarly journals Measurement report: Vehicle-based and In Situ Multi-lidar Observational Study on the Effect of Meteorological Elements on the Three-dimensional Distribution of Particles in the Western Guangdong–Hong Kong–Macao Greater Bay Area

2021 ◽  
Author(s):  
Xinqi Xu ◽  
Jielan Xie ◽  
Yuman Li ◽  
Shengjie Miao ◽  
Shaojia Fan
Keyword(s):  
Boundary Layer ◽  
Hong Kong ◽  
Vertical Distribution ◽  
Three Dimensional ◽  
Single Layer ◽  
Bay Area ◽  
Dimensional Distribution ◽  
Meteorological Elements ◽  
Horizontal And Vertical Distribution

Abstract. The distribution of meteorological elements has always been an important factor in determining the horizontal and vertical distribution of particles in the atmosphere. To study the effect of meteorological elements on the three-dimensional distribution structure of particles, mobile vehicle lidar observations, and in situ observations were presented in the western Guangdong–Hong Kong–Macao Greater Bay Area of China during September and October of 2019 and 2020. Vertical aerosol extinction coefficient, depolarization ratio, wind and temperature profiles were measured by using a micro pulse lidar, a Raman scattering lidar, and a Doppler wind profile lidar installed on a mobile monitoring vehicle. The mechanism of how wind and temperature in the boundary layer affects the horizontal and vertical distribution of particles was analyzed. The result showed that particles were mostly distributed in downstream areas on days with moderate wind speed in the boundary layer, while they presented homogeneously on days with weaker wind. There are three typical types of vertical distribution of particles in the western Guangdong–Hong Kong–Macao Greater Bay Area (GBA): surface single layer, elevated single layer, and double layer. Analysis of wind profiles and Hybrid Single-Particle Lagrangian Integrated Trajectory Model (HYSPLIT) backward trajectory revealed different sources of particles for the three types. Particles concentrated near the temperature inversion and multiple inversions could cause more than one peak in the extinction coefficient profile. There are two mechanisms that affected the distribution of particulate matter in the upper and lower boundary layers. Based on observational study, a general model of meteorological elements affecting the vertical distribution of urban particulate matter was made.

A review of turbulence in the very stable nocturnal boundary layer and its implications for air quality

2005 ◽  
Vol 29 (2) ◽  
pp. 171-188 ◽  
Author(s):  
J. A. Salmond ◽  
I. G. McKendry
Keyword(s):  
Boundary Layer ◽  
Air Quality ◽  
Spatial Scales ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Nocturnal Boundary Layer ◽  
Dimensional Distribution ◽  
Temporal And Spatial ◽  
Fraser Valley ◽  
Spatial And Temporal Characteristics

Turbulence in the very stable nocturnal boundary layer is weak and typically characterized by intermittent bursts of activity. It often exists in isolated layers or pockets generated primarily from localized shear instabilities. As a result, turbulence is rarely in equilibrium with the conditions of the underlying surface. Given the layered structure of the nocturnal boundary layer, the spatial and temporal characteristics of turbulent activity (and resulting vertical mixing) can have a significant affect on local air quality at hourly to diurnal scales. However, while there is a wealth of information concerning turbulent processes operating during daytime conditions, until recently comparatively few studies have focused on the nocturnal case. Nevertheless the three-dimensional distribution of pollutants in the nocturnal boundary layer may have a significant impact on local pollutant budgets at a variety of temporal and spatial scales. This paper reviews recent progress in our understanding of the structure of, and processes operating in, the very stable nocturnal boundary layer. Then, drawing upon case studies from the Lower Fraser Valley, of British Columbia, Canada, it considers the implications of these developments for pollutant transport and surface air quality.

scholarly journals A place in space - the horizontal vs vertical factors that influence zooplankton (Rotifera, Crustacea) communities in a mesotrophic lake

2019 ◽  
Vol 78 (2) ◽  
Author(s):  
Maciej Karpowicz ◽  
Jolanta Ejsmont-Karabin ◽  
Adam Więcko ◽  
Andrzej Górniak ◽  
Adam Cudowski
Keyword(s):  
Vertical Distribution ◽  
Three Dimensional ◽  
Distribution Patterns ◽  
Vertical Gradient ◽  
Primary Objective ◽  
Phytoplankton Distribution ◽  
Warm Surface Water ◽  
Dimensional Distribution ◽  
Daphnia Cucullata ◽  
Plankton Distribution

The factors that influence plankton distribution in lakes are currently widely debated. The primary objective of this study was to determine a combination of factors that influence the three-dimensional distribution patterns of both rotifer and crustacean communities in a pelagic ecosystem. We compared the abiotic (temperature, oxygen and nutrients) and biotic (phytoplankton) factors that affect the horizontal and vertical distribution of zooplankton in different habitat conditions in Lake Wigry. The results of our study indicate that the vertical gradient in a water profile is much more important for microcrustaceans than horizontal changes in environmental conditions, whereas Rotifera showed a strong spatial autocorrelation when connected with differences in trophic status. Generally, large zooplankton prefer cold, darker waters of the metalimnion-hypolimnion, while smaller zooplankton prefer the warm epilimnion. This niche segregation in water profiles promotes a large diversity of pelagic zooplankton. The vertical distribution of dominant Daphnia cucullata was strongly related to the phytoplankton distribution. Moreover, we found that the large-bodied Daphnia cucullata prefers the lower water layers, despite the presence of less optimal food resources, while smaller individuals clearly prefer the warm surface water with high quality resources.

scholarly journals Measurement report: Vertical distribution of atmospheric particulate matter within the urban boundary layer in southern China – size-segregated chemical composition and secondary formation through cloud processing and heterogeneous reactions

2020 ◽  
Vol 20 (11) ◽  
pp. 6435-6453 ◽  
Author(s):  
Shengzhen Zhou ◽  
Luolin Wu ◽  
Junchen Guo ◽  
Weihua Chen ◽  
Xuemei Wang ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particulate Matter ◽  
Vertical Distribution ◽  
Aqueous Phase ◽  
Ground Level ◽  
Urban Boundary Layer ◽  
Water Soluble ◽  
Heterogeneous Reactions ◽  
Formation Mechanisms ◽  
Autumn And Winter

Abstract. Many studies have recently been done on understanding the sources and formation mechanisms of atmospheric aerosols at ground level. However, vertical profiles and sources of size-resolved particulate matter within the urban boundary layer are still lacking. In this study, vertical distribution characteristics of size-segregated particles were investigated at three observation platforms (ground level, 118 m, and 488 m) on the 610 m high Canton Tower in Guangzhou, China. Size-segregated aerosol samples were simultaneously collected at the three levels in autumn and winter. Major aerosol components, including water-soluble ions, organic carbon, and elemental carbon, were measured. The results showed that daily average fine-particle concentrations generally decreased with height. Concentrations of sulfate and ammonium in fine particles displayed shallow vertical gradients, and nitrate concentrations increased with height in autumn, while the chemical components showed greater variations in winter than in autumn. The size distributions of sulfate and ammonium in both seasons were characterized by a dominant unimodal mode with peaks in the size range of 0.44–1.0 µm. In autumn, the nitrate size distribution was bimodal, peaking at 0.44–1.0 and 2.5–10 µm, while in winter it was unimodal, implying that the formation mechanisms for nitrate particles were different in the two seasons. Our results suggest that the majority of the sulfate and nitrate is formed from aqueous-phase reactions, and we attribute coarse-mode nitrate formation at the measurement site to the heterogeneous reactions of gaseous nitric acid on existing sea-derived coarse particles in autumn. Case studies further showed that atmospheric aqueous-phase and heterogeneous reactions could be important mechanisms for sulfate and nitrate formation, which, in combination with adverse weather conditions such as temperature inversion and calm wind, led to haze formation during autumn and winter in the Pearl River Delta (PRD) region.

scholarly journals Ecological Livability Assessment of Urban Agglomerations in Guangdong-Hong Kong-Macao Greater Bay Area

2021 ◽  
Vol 18 (24) ◽  
pp. 13349
Author(s):  
Zengzeng Fan ◽  
Yuanyang Wang ◽  
Yanchao Feng
Keyword(s):  
Hong Kong ◽  
Three Dimensional ◽  
Evaluation Framework ◽  
Spatial Dynamic ◽  
Dynamic Panel ◽  
Dynamic Panel Model ◽  
The Third ◽  
Bay Area ◽  
Panel Model ◽  
Second Tier

This paper proposes the “citizen-ecology-city” evaluation framework for urban ecological livability theoretically and studies the ecological livability of the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) empirically. In addition, we analyze the factors of urban ecological livability in a spatial dynamic panel model. The results are as follows. (1) Ecological livability levels of Macao and Hong Kong are significantly higher than the nine cities in the PRD; (2) Shenzhen and Guangzhou lead the nine cities in the PRD, while Jiangmen and Zhaoqing perform poorly; (3) GBA cities can be divided into three categories: Macao, Hong Kong, Shenzhen, and Guangzhou in the first tier; Zhuhai, Foshan, and Dongguan in the second tier; Huizhou, Zhongshan, Jiangmen, and Zhaoqing in the third tier; and (4) The ecological livability of the GBA cities has a characteristic of spatial correlation. In terms of the international value, the three-dimensional evaluation framework can apply to other bay areas in the world.

Visualization of Microbubble Distribution Inside Turbulent Boundary Layer Along Flat and Curved Solid Surfaces

2019 ◽  
Author(s):  
Yuichi Murai ◽  
Daichi Saito ◽  
Daiki Ushiyama ◽  
Hyun Jin Park ◽  
Yuji Tasaka
Keyword(s):  
Boundary Layer ◽  
Solid Wall ◽  
Three Dimensional ◽  
Elliptic Cylinder ◽  
Water Electrolysis ◽  
Solid Surfaces ◽  
Curvature Radius ◽  
Liquid Boundary ◽  
Dimensional Distribution ◽  
Liquid Boundary Layer

Abstract How microbubbles behave inside turbulent boundary layers are investigated experimentally. Water electrolysis is applied for generation of microbubbles in water, of which electrodes are flash mounted on the solid wall in the upstream section of the measurement area. Four kinds of solid surfaces are examined to compare the microbubble distribution. For a circular cylinder of the radius R = 22 mm at Re = 5,000, we found that microbubbles depart from the surface earlier than the liquid boundary layer. For an elliptic cylinder of the curvature radius of R = 60 mm and a hydrofoil of NACA0040, microbubble injection made the separation point move downstream in the range of 9,000 < Re < 90,000. To compare the effect with the cases of flat solid surfaces (R = infinity), we visualized three-dimensional distribution of microbubbles with color-coded volumetric illumination technique. The result has shown formation of microbubble clusters intermittently, which has Coulomb potential due to negative electric charge on bubble interfaces.

scholarly journals Deleterious localized stress fields: the effects of boundaries and stiffness tailoring in anisotropic laminated plates

2016 ◽  
Vol 472 (2194) ◽  
pp. 20160391 ◽  
Author(s):  
R. M. J. Groh ◽  
P. M. Weaver
Keyword(s):  
Boundary Layer ◽  
Composite Laminates ◽  
Three Dimensional ◽  
Single Layer ◽  
Variable Stiffness ◽  
Laminated Plates ◽  
Stress Fields ◽  
Relative Significance ◽  
Shear Moduli ◽  
Constant Stiffness

The safe design of primary load-bearing structures requires accurate prediction of stresses, especially in the vicinity of geometric discontinuities where deleterious three-dimensional stress fields can be induced. Even for thin-walled structures significant through-thickness stresses arise at edges and boundaries, and this is especially precarious for laminates of advanced fibre-reinforced composites because through-thickness stresses are the predominant drivers in delamination failure. Here, we use a higher-order equivalent single-layer model derived from the Hellinger–Reissner mixed variational principle to examine boundary layer effects in laminated plates comprising constant-stiffness and variable-stiffness laminae and deforming statically in cylindrical bending. The results show that zigzag deformations, which arise due to layerwise differences in the transverse shear moduli, drive boundary layers towards clamped edges and are therefore critically important in quantifying localized stress gradients. The relative significance of the boundary layer scales with the degree of layerwise anisotropy and the thickness to characteristic length ratio. Finally, we demonstrate that the phenomenon of alternating positive and negative transverse shearing deformation through the thickness of composite laminates, previously only observed at clamped boundaries, can also occur at other locations as a result of smoothly varying the material properties over the in-plane dimensions of the laminate.

scholarly journals Assessing Ecological Carrying Capacity in the Guangdong-Hong Kong-Macao Greater Bay Area Based on a Three-Dimensional Ecological Footprint Model

2020 ◽  
Vol 12 (22) ◽  
pp. 9705
Author(s):  
Ye-Ning Wang ◽  
Qiang Zhou ◽  
Hao-Wei Wang
Keyword(s):  
Hong Kong ◽  
Carrying Capacity ◽  
Ecological Footprint ◽  
Natural Capital ◽  
Three Dimensional ◽  
Footprint Model ◽  
Ecological Carrying Capacity ◽  
Ecological Deficit ◽  
Bay Area ◽  
Utilization Patterns

As one of the most developed and competitive metropolitan areas in the world, the contradiction between resource depletion and sustainable development in the Guangdong-Hong Kong-Macao Greater Bay Area (GHMGBA) has become a crucial issue nowadays. This paper analyzed the natural capital utilization patterns in GHMGBA during 2009–2016 based on a three-dimensional ecological footprint model. Ecological carrying capacity intensity (ECintensity) was calculated to optimize the accounting of ecological carrying capacity (EC). Ecological footprint depth (EFdepth) and ECintensity were quantitatively investigated and influencing factors were further explored based on a partial least squares (PLS) model. Results showed that GHMGBA had been operating in a deficit state due to the shortage of natural capital flow and accumulated stock depletion. The highest EFdepth occurred in Macao (17.11~26.21) and Zhongshan registering the lowest (2.42~3.58). Cropland, fossil energy and construction land constituted the most to total ecological deficit, while woodland was continuously in a slight surplus. Natural capital utilization patterns of 11 cities were divided into four categories through hierarchical clustering analysis. Driving factors of EFdepth, ECintensity and three-dimensional ecological deficit (ED3D) were mainly students in primary and secondary education, disposable income, consumption expenditure, R&D personnel and freight volume. Our findings could provide guidance for decision-makers to develop resource utilization portfolios in GHMGBA.

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