scholarly journals Vertical Distribution of Particulates within the Near-Surface Layer of Dry Bulk Port and Influence Mechanism: A Case Study in China

2019 ◽  
Vol 11 (24) ◽  
pp. 7135 ◽  
Author(s):  
Jinxing Shen ◽  
Xuejun Feng ◽  
Kai Zhuang ◽  
Tong Lin ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Weather Conditions ◽  
Dust Suppression ◽  
Near Surface ◽  
Cargo Handling ◽  
Port Operation ◽  
Pm10 And Pm2.5 ◽  
The Impact ◽  
The Vertical Distribution ◽  
Porous Fence

Knowing the vertical distribution of ambient particulate matter (PM) will help port authorities choose the optimal dust-suppression measures to reduce PM concentrations. In this study, we used an unmanned aerial vehicle (UAV) to assess the vertical distribution (0–120 m altitude) of PM in a dry bulk port along the Yangtze River, China. Total suspended particulates (TSP), PM10, and PM2.5 concentrations at different altitudes were measured at seven sites representing different cargo-handling sites and a background site. Variations in results across sites make it not suitable to characterize the vertical distribution of PM concentration at this port using simple representative distributions. Bulk cargo particle size, fog cannon use, and porous fence all affected the vertical distribution of TSP concentrations but had only minor impacts on PM10 and PM2.5 concentrations. Optimizing porous fence layout according to weather conditions and cargo demand at port have the most potential for mitigating PM pollution related to port operation. As ground-based stations cannot fully measure vertical PM distributions, our methods and results represent an advance in assessing the impact of port activities on air quality and can be used to determine optimal dust-suppression measures for dry bulk ports.

scholarly journals Multi-model study of mercury dispersion in the atmosphere: Vertical distribution of mercury species

2016 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
The Impact ◽  
The Vertical Distribution

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model inter-comparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground based observations of mercury concentration and deposition, here we investigate the vertical distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on inter-continental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including inter-hemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury (RM) patterns depending on altitude. High RM concentrations in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parametrizations in the chemistry transport models also proved to have a substantial impact on model results.

Geothermal Geotechnics development program as a commonly used solution in D-wall.

2021 ◽  
Author(s):  
Grzegorz Kacprzak ◽  
Tomasz Stasiukiewicz ◽  
Rafał Bagiński ◽  
Mateusz Frydrych ◽  
Marcin Piotrowski
Keyword(s):  
Development Program ◽  
Weather Conditions ◽  
Energy Utilization ◽  
Building Structures ◽  
Deep Foundation ◽  
Ansys Fluent ◽  
Near Surface ◽  
Building Maintenance ◽  
Diaphragm Walls ◽  
The Impact

<p>The project relates to an idea consisting in the use of diaphragm walls constituting a substructure system most often used during the foundation of a large volume building structure in tight urban fabric. Additionally, it offers the possibility of using this substructure as near-surface geothermal geotechnics and in conjunction with adjacent soil as an interseason heat storage in the form of enclosed box. The effect of the following development program is expected to provide a product in the form of concrete elements, that are already required for structural reasons, as diaphragm walls and barrettes with an integrated geothermal installation that allows obtaining part of the heat energy necessary for the operation of a renewable energy building. The accumulated energy, in the form of a lower energy source will be used to heat the building in winter. In summer,  the reduced temperature of diaphragm walls in relation to weather conditions will allow the building to cool down, and thus will power air conditioning systems. This will feature not only concerns about environment aspects but also provides a long-term cost-saving solution that will limit building maintenance.</p><p>Presented, currently running, two years program is an effect of cooperation between experienced deep foundation contractor and The Institute of Heat Engineering, scientific unit. The development program, presented below, is based on the industrial research phase in which the lower heat source systems are modelled in Ansys Fluent and then the calculation results are reproduced under laboratory conditions on small physical 3x2x0.7m models. The results from measurements with temperature sensors and IR cameras are used to calibrate the FEM models and to determine the most optimal distribution of the pipes with the fluid carrier.  Stage 2 will allow the analysis of the impact of thermal stress generated by the geothermal installation on the construction of the diaphragm walls and the entire building using deformation sensors.  Development works in stage 3 will allow verification of the above assumptions using real commercial construction in the interseasonal cycle.</p><p>The most significant effect of the development programme, stage 4,  will be the creation of a simple tool, on the basis of empirical data collected during model works and prototype tests, to commonly determine the thermal balance for building structures under given ground conditions for commercial buildings. The aim of the tool, being acquired by a deep foundation contractor, is a popularization of the thermo-active ground structures <span>solutions </span><span>and promotion of geothermal energy utilization.</span></p>

scholarly journals Seasonal cycle of desert aerosols in western Africa: analysis of the coastal transition with passive and active sensors

2017 ◽  
Vol 17 (13) ◽  
pp. 8395-8410 ◽  
Author(s):  
Habib Senghor ◽  
Éric Machu ◽  
Frédéric Hourdin ◽  
Amadou Thierno Gaye
Keyword(s):  
Vertical Distribution ◽  
Satellite Observations ◽  
Boreal Summer ◽  
Wide Field ◽  
Aerosol Layer ◽  
Good Representation ◽  
Mineral Aerosols ◽  
Western Africa ◽  
The Impact ◽  
The Vertical Distribution

Abstract. The impact of desert aerosols on climate, atmospheric processes, and the environment is still debated in the scientific community. The extent of their influence remains to be determined and particularly requires a better understanding of the variability of their distribution. In this work, we studied the variability of these aerosols in western Africa using different types of satellite observations. SeaWiFS (Sea-Viewing Wide Field-of-View Sensor) and OMI (Ozone Monitoring Instrument) data have been used to characterize the spatial distribution of mineral aerosols from their optical and physical properties over the period 2005–2010. In particular, we focused on the variability of the transition between continental western African and the eastern Atlantic Ocean. Data provided by the lidar scrolling CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) onboard the satellite CALIPSO (Cloud Aerosol Lidar and Infrared Pathfinder Satellite Observations) for the period 2007–2013 were then used to assess the seasonal variability of the vertical distribution of desert aerosols. We first obtained a good representation of aerosol optical depth (AOD) and single-scattering albedo (SSA) from the satellites SeaWiFS and OMI, respectively, in comparison with AERONET estimates, both above the continent and the ocean. Dust occurrence frequency is higher in spring and boreal summer. In spring, the highest occurrences are located between the surface and 3 km above sea level, while in summer the highest occurrences are between 2 and 5 km altitude. The vertical distribution given by CALIOP also highlights an abrupt change at the coast from spring to fall with a layer of desert aerosols confined in an atmospheric layer uplifted from the surface of the ocean. This uplift of the aerosol layer above the ocean contrasts with the winter season during which mineral aerosols are confined in the atmospheric boundary layer. Radiosondes at Dakar Weather Station (17.5° W, 14.74° N) provide basic thermodynamic variables which partially give a causal relationship between the layering of the atmospheric circulation over western Africa and their aerosol contents throughout the year. A SSA increase is observed in winter and spring at the transition between the continent and the ocean. The analysis of mean NCEP (National Centers for Environmental Prediction) winds at 925 hPa between 2000 and 2012 suggest a significant contribution of coastal sand sources from Mauritania in winter which would increase SSA over the ocean.

An Airborne Profiling Radar Study of the Impact of Glaciogenic Cloud Seeding on Snowfall from Winter Orographic Clouds

2010 ◽  
Vol 67 (10) ◽  
pp. 3286-3302 ◽  
Author(s):  
Bart Geerts ◽  
Qun Miao ◽  
Yang Yang ◽  
Roy Rasmussen ◽  
Daniel Breed
Keyword(s):  
Doppler Radar ◽  
Weather Conditions ◽  
Cold Season ◽  
Near Surface ◽  
Medicine Bow Mountains ◽  
Orographic Clouds ◽  
Surface Reflectivity ◽  
Glaciogenic Seeding ◽  
The Impact ◽  
Composite Data

Abstract Data from an airborne vertically pointing millimeter-wave Doppler radar are used to study the cloud microphysical effect of glaciogenic seeding of cold-season orographic clouds. Fixed flight tracks were flown downstream of ground-based silver iodide (AgI) generators in the Medicine Bow Mountains of Wyoming. Composite data from seven flights, each with a no-seeding period followed by a seeding period, indicate that radar reflectivity was higher near the ground during the seeding periods. Several physical considerations argue in favor of the hypothesis that the increase in near-surface reflectivity is attributed to AgI seeding. While the increase in near-surface reflectivity and thus snowfall rate are statistically significant, caution is warranted in view of the large natural variability of weather conditions and the small size of the dataset.

scholarly journals Shrub type dominates the vertical distribution of leaf C : N : P stoichiometry across an extensive altitudinal gradient

2017 ◽  
Author(s):  
Wenqiang Zhao ◽  
Peter B. Reich ◽  
Qiannan Yu ◽  
Ning Zhao ◽  
Chunying Yin ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Altitudinal Gradient ◽  
Environmental Changes ◽  
Interactive Effects ◽  
The Tibetan Plateau ◽  
Longitudinal Gradients ◽  
Leaf Stoichiometry ◽  
The Impact ◽  
The Vertical Distribution ◽  
Leaf N

Abstract. Understanding the leaf stoichiometric patterns is crucial for improving predictions on plant responses to environmental changes. Leaf stoichiometry of terrestrial ecosystems has been widely investigated along latitudinal and longitudinal gradients. Still, very little is known on the vertical distribution of leaf C : N : P and the relative effects of environmental parameters, especially for shrubs. Here, we analyzed the shrub leaf C, N and P patterns in 125 mountainous sites over an extensive altitudinal gradient (523–4685 m) on the Tibetan Plateau. Results showed that the shrub leaf C and C : N were 7.3 %–47.5 % higher than those of other regional and global flora, whereas the leaf N and N : P were 10.2 %–75.8 % lower. Leaf C increased with rising altitude and decreasing temperature, supporting the physiological acclimation mechanism that high leaf C (e.g., alpine or evergreen shrub) could balance the cell osmotic pressure and resist freezing. The largest leaf N and high leaf P occurred in valley region (altitude 1500 m), likely due to the large nutrient leaching from higher elevations, faster litter decomposition and nutrient resorption ability of deciduous broadleaf shrub. Leaf N : P ratio further indicated increasing N limitation at higher altitudes. Interestingly, the drought severity was the only climatic factor positively correlated with leaf N and P, which was more appropriate for evaluating the impact of water status than precipitation. Among the shrub ecosystem and functional types (alpine, subalpine, montane, valley, evergreen, deciduous, broadleaf, and conifer), their leaf element contents and responses to environments were remarkably different. Shrub type was the largest contributor to the total variations in leaf stoichiometry, while climate indirectly affected the leaf C : N : P via its interactive effects on shrub type or soil. Collectively, the large heterogeneity in shrub type was the most important factor explaining the overall leaf C : N : P variations, despite the broad climate gradient on the plateau. Temperature- and drought-induced shift of shrub type distribution will influence the nutrient accumulation in mountainous shrubs.

scholarly journals Identifying optical turbulence profiles for realistic tomographic error in adaptive optics

2019 ◽  
Vol 488 (1) ◽  
pp. 213-221 ◽  
Author(s):  
O J D Farley ◽  
J Osborn ◽  
T Morris ◽  
T Fusco ◽  
B Neichel ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Adaptive Optics ◽  
Compute Tomographic ◽  
Distribution Profile ◽  
Statistical Sample ◽  
Large Telescopes ◽  
The Impact ◽  
First Time ◽  
The Vertical Distribution ◽  
Performance Estimates

ABSTRACT For extremely large telescopes, adaptive optics will be required to correct the Earth’s turbulent atmosphere. The performance of tomographic adaptive optics is strongly dependent on the vertical distribution (profile) of this turbulence. An important way in which this manifests is the tomographic error, arising from imperfect measurement and reconstruction of the turbulent phase at altitude. Conventionally, a small number of reference profiles are used to obtain this error in simulation; however these profiles are not constructed to be representative in terms of tomographic error. It is therefore unknown whether these simulations are providing realistic performance estimates. Here, we employ analytical adaptive optics simulation that drastically reduces computation times to compute tomographic error for 10 691 measurements of the turbulence profile gathered by the Stereo-SCIDAR instrument at ESO Paranal. We assess for the first time the impact of the profile on tomographic error in a statistical manner. We find, in agreement with previous work, that the tomographic error is most directly linked with the distribution of turbulence into discrete, stratified layers. Reference profiles are found to provide mostly higher tomographic error than expected, which we attribute to the fact that these profiles are primarily composed of averages of many measurements resulting in unrealistic, continuous distributions of turbulence. We propose that a representative profile should be defined with respect to a particular system, and that as such simulations with a large statistical sample of profiles must be an important step in the design process.

scholarly journals Depth is Relative: The Importance of Depth on TEP in the Near Surface Environment

2019 ◽  
Author(s):  
Tiera-Brandy Robinson ◽  
Christian Stolle ◽  
Oliver Wurl
Keyword(s):  
Vertical Distribution ◽  
Spatial Scales ◽  
Small Scale ◽  
Surface Microlayer ◽  
Near Surface ◽  
Chl A ◽  
Sea Surface Microlayer ◽  
Carbon Transfer ◽  
The Vertical Distribution ◽  
Surface Environment

Abstract. Transparent exopolymer particles (TEP) are a major source for both organic matter (OM) and carbon transfer in the ocean and into the atmosphere. Consequently, understanding the vertical distribution of TEP and the processes which impact its movement are important in understanding the OM and carbon pools on a larger scale. Additionally, most studies looking at the vertical profile of TEP have focused on large depth scales from 5 to 1000s meters and have omitted the near surface environment. Results from a study of TEP enrichment in the sea surface microlayer (SML) in different regions (tropical, temperate) has shown that while there is a correlation between TEP abundance and primary production (PP) on larger or seasonal scales, such relationships break down on shorter time and spatial scales. Using a novel small-scale vertical sampler, the vertical distribution of TEP within the uppermost 2 meters was investigated. With a maximum variance of TEP abundance between depths (1.39 × 106 µg XG eq2 L-2) and a minimum variance of (6 × 102 µg XG eq2 L-2) the vertical distribution of TEP was found to be both heterogeneous and homogeneous at times. Results from the enrichment of TEP and Chl a between different regions has shown TEP enrichment to be greater in oligotrophic waters, when both Chl a and TEP abundance was low, suggesting the importance of abiotic sources for the enrichment of TEP in the SML. However, considering multiple additional parameters that were sampled, it is clear that no single parameter could be used as a proxy for TEP heterogeneity, other probable biochemical drivers of TEP transport are discussed.

Wind Erosion at a Saline Playa Environment, Ebinur Lake, Xinjiang, China - A Case Study on the Source of Saline Dust Storm

2012 ◽  
Vol 260-261 ◽  
pp. 1003-1008
Author(s):  
Dong Wei Liu ◽  
Jilili Abuduwaili
Keyword(s):  
Vertical Distribution ◽  
Wind Erosion ◽  
Dust Storms ◽  
Aeolian Transport ◽  
Near Surface ◽  
Erosion Pins ◽  
Dry Lake ◽  
The Vertical Distribution ◽  
Main Factor

In many arid and semiarid lands, dry lake beds (saline playa) represent a tremendous source of unconsolidated salt-rich sediments that are available for aeolian transport. Severe salt-dust storms caused by the erosion of such landforms have become very harmful natural phenomena. Base on texture and appearance characteristic, five principal undisturbed playa surfaces for sampling to investigate the deflation rate and the vertical distribution of material abraded using a wind-tunnel experiment in this study. Two additional field deflation monitoring transect were aslo established to examine vertical deflation by wind from measurements of erosion pins at the Ebinur (dry) Lake. The results indicate that winds greater than 8 m/s is the main factor for inducing the erosion of the playa sediments. Soft salt, aeloian sediment and alluvial deposit are the main sources of the saline dust storms in Ebinur region. The near-surface vertical distribution of material abraded concentrated in 0 -10 cm height. The annual wind erosion rate ranged from 0.48 cm to 5.6 cm in the northwest portion of the lake and from 0.24 cm to 0.96 cm in the southeast portion.

The stability of vertical distribution profiles of insects in air layers near the ground

2000 ◽  
Vol 78 (12) ◽  
pp. 2167-2173 ◽  
Author(s):  
Gilles Boiteau ◽  
Walter PL Osborn ◽  
Xingyao Xiong ◽  
Yves Bousquet
Keyword(s):  
Apis Mellifera ◽  
Vertical Distribution ◽  
Coccinella Septempunctata ◽  
Lygus Lineolaris ◽  
Air Layers ◽  
Insect Monitoring ◽  
Regression Slopes ◽  
The Stability ◽  
The Impact ◽  
The Vertical Distribution

The vertical distribution of insect orders, families, and species captured over 10 elevations from the ground to 15 m over 4 years in a potato agro-ecosystem differed considerably within and between taxa. Regression slopes representing these aerial profiles remained similar over the 4 years of the study for orders Thysanoptera, Neuroptera, and Psocoptera, changed considerably for Hemiptera, Homoptera and Ephemeroptera, and were statistically non-homogeneous for Coleoptera, Hymenoptera, Diptera, Lepidoptera, Trichoptera, and Plecoptera. The slopes of the aerial profiles for families remained similar over the years for Carabidae and Elateridae, changed for Staphylinidae, Meloidae, and Scarabeidae, but were statistically non-homogeneous for Coccinellidae, Miridae, and Aphididae. The slopes of the aerial profiles for insect species were similar across years for Coccinella septempunctata L., Melanotus similis (Kirby), and Anatis mali Say, changed for Pyrrhalta luteola (Mull.), Ctenicera pulchra LeConte, Ctenicera tarsalis Melsheimer, Coccinella trifasciata perplexa Muls., Lygus lineolaris (P. de B.), Ctenicera appropinquans Randall, Apis mellifera L., and Adalia bipunctata (L.), but were significantly non-homogeneous only for Hippodamia convergens G.-M. Although most profiles obtained for insect orders in this study were remarkably similar to those reported in the literature, the level of between-year variation at our study site suggests that there is considerable overlap between profiles at all taxon levels. Vertical aerial profiles cannot be considered sufficiently characteristic of the species, family, or order across years for use as indicators of change in biodiversity. The impact of these results on insect monitoring are discussed.

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