Impact of vehicular emissions in an urban area of the Po valley by microscale simulation with the GRAL dispersion model

Abstract. This paper describes the City-scale Chemistry (CityChem) extension of the urban dispersion model EPISODE with the aim to enable chemistry/transport simulations of multiple reactive pollutants on urban scales. The new model is called CityChem-EPISODE. The primary focus is on the simulation of urban ozone concentrations. Ozone is produced in photochemical reaction cycles involving nitrogen oxides (NOx) and volatile organic compounds (VOC) emitted by various anthropogenic activities in the urban area. The performance of the new model was evaluated with a series of synthetic tests and with a first application to the air quality situation in the city of Hamburg, Germany. The model performs fairly well for ozone in terms of temporal correlation and bias at the air quality monitoring stations in Hamburg. In summer afternoons, when photochemical activity is highest, modelled median ozone at an inner-city urban background station was about 30 % lower than the observed median ozone. Inaccuracy of the computed photolysis frequency of nitrogen dioxide (NO2) is the most probable explanation for this. CityChem-EPISODE reproduces the spatial variation of annual mean NO2 concentrations between urban background, traffic and industrial stations. However, the temporal correlation between modelled and observed hourly NO2 concentrations is weak for some of the stations. For daily mean PM10, the performance of CityChem-EPISODE is moderate due to low temporal correlation. The low correlation is linked to uncertainties in the seasonal cycle of the anthropogenic particulate matter (PM) emissions within the urban area. Missing emissions from domestic heating might be an explanation for the too low modelled PM10 in winter months. Four areas of need for improvement have been identified: (1) dry and wet deposition fluxes; (2) treatment of photochemistry in the urban atmosphere; (3) formation of secondary inorganic aerosol (SIA); and (4) formation of biogenic and anthropogenic secondary organic aerosol (SOA). The inclusion of secondary aerosol formation will allow for a better sectorial attribution of observed PM levels. Envisaged applications of the CityChem-EPISODE model are urban air quality studies, environmental impact assessment, sensitivity analysis of sector-specific emission and the assessment of local and regional emission abatement policy options.

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High-resolution mapping of vehicle emissions of atmospheric pollutants based on large-scale, real-world traffic datasets

10.5194/acp-2019-32 ◽

2019 ◽

Author(s):

Daoyuan Yang ◽

Shaojun Zhang ◽

Tianlin Niu ◽

Yunjie Wang ◽

Honglei Xu ◽

...

Keyword(s):

Urban Area ◽

Real World ◽

Vehicle Emissions ◽

Large Scale ◽

Emission Inventory ◽

Road Traffic ◽

Dispersion Model ◽

Traffic Monitoring ◽

Atmospheric Pollutants ◽

Link Model

Abstract. On-road vehicle emissions are a major contributor to elevated air pollution levels in populous metropolitan areas. We developed a link-level emissions inventory of vehicular pollutants, called EMBEV-Link, based on multiple datasets extracted from the extensive road traffic monitoring network that covers the entire municipality of Beijing, China (16 400 km2). We employed the EMBEV-Link model under various traffic scenarios to capture the significant variability in vehicle emissions, temporally and spatially, due to the real-world traffic dynamics and the traffic restrictions implemented by the local government. The results revealed high carbon monoxide (CO) and total hydrocarbon (THC) emissions in the urban area (i.e., within the Fifth Ring Road) and during rush hours, both associated with the passenger vehicle traffic. By contrast, considerable fractions of nitrogen oxides (NOX), fine particulate matter (PM2.5) and black carbon (BC) emissions were present beyond the urban area, as heavy-duty trucks (HDTs) were not allowed to drive through the urban area during daytime. The EMBEV-Link model indicates that non-local HDTs could for 29 % and 38 % of estimated total on-road emissions of NOX and PM2.5, which were ignored in previous conventional emission inventories. We further combined the EMBEV-Link emission inventory and a computationally efficient dispersion model, RapidAir®, to simulate vehicular NOX concentrations at fine resolutions (10 m × 10 m in the entire municipality and 1 m × 1 m in the hotspots). The simulated results indicated a close agreement with ground observations and captured sharp concentration gradients from line sources to ambient areas. During the nighttime when the HDT traffic restrictions are lifted, HDTs could be responsible for approximately 10 μg m−3 of NOX in the urban area. The uncertainties of conventional top-down allocation methods, which were widely used to enhance the spatial resolution of vehicle emissions, are also discussed by comparison with the EMBEV-Link emission inventory.

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Construction and validation of an urban area flow and dispersion model on building scales

Acta Meteorologica Sinica ◽

10.1007/s13351-013-0504-1 ◽

2013 ◽

Vol 27 (6) ◽

pp. 923-941 ◽

Cited By ~ 8

Author(s):

Bicheng Chen ◽

Shuhua Liu ◽

Yucong Miao ◽

Shu Wang ◽

Yuan Li

Keyword(s):

Urban Area ◽

Dispersion Model

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Use of a new generation urban scale dispersion model to estimate the concentration of oxides of nitrogen and sulphur dioxide in a large urban area

The Science of The Total Environment ◽

10.1016/s0048-9697(99)00205-3 ◽

1999 ◽

Vol 235 (1-3) ◽

pp. 277-291 ◽

Cited By ~ 20

Author(s):

B Owen ◽

H.A Edmunds ◽

D.J Carruthers ◽

D.W Raper

Keyword(s):

Urban Area ◽

Sulphur Dioxide ◽

Dispersion Model ◽

Oxides Of Nitrogen ◽

Large Urban Area ◽

New Generation

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Mass closure on the chemical species in size-segregated atmospheric aerosol collected in an urban area of the Po Valley, Italy

Atmospheric Chemistry and Physics ◽

10.5194/acp-3-623-2003 ◽

2003 ◽

Vol 3 (3) ◽

pp. 623-637 ◽

Cited By ~ 79

Author(s):

E. Matta ◽

M. C. Facchini ◽

S. Decesari ◽

M. Mircea ◽

F. Cavalli ◽

...

Keyword(s):

Urban Area ◽

Organic Compounds ◽

Functional Group ◽

Group Analysis ◽

Chemical Species ◽

Water Soluble ◽

Proton Nuclear Magnetic Resonance ◽

Mass Closure ◽

Po Valley ◽

Functional Group Analysis

Abstract. A complete size segregated chemical characterisation was carried out for aerosol samples collected in the urban area of Bologna over a period of one year, using five-stage low pressure Berner impactors. An original dual-substrate technique was adopted to obtain samples suitable for a complete chemical characterisation. Total mass, inorganic, and organic components were analysed as a function of size, and a detailed characterisation of the water soluble organic compounds was also performed by means of a previously developed methodology, based on HPLC separation of organic compounds according to their acid character and functional group analysis by Proton Nuclear Magnetic Resonance. Chemical mass closure of the collected samples was reached to within a few percent on average in the submicron aerosol range, while a higher unknown fraction in the coarse aerosol range was attributed to soil-derived species not analysed in this experiment. Comparison of the functional group analysis results with model results simulating water soluble organic compound production by gas-to-particle conversion of anthropogenic VOCs showed that this pathway provides a minor contribution to the organic composition of the aerosol samples in the urban area of Bologna.

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Evaluation of ammonia emissions from filtration of digestate used for fertigation

Journal of Agricultural Engineering ◽

10.4081/jae.2021.1187 ◽

2021 ◽

Vol 52 (3) ◽

Author(s):

Celeste Righi Ricco ◽

Alberto Finzi ◽

Viviana Guido ◽

Elisabetta Riva ◽

Omar Ferrari ◽

...

Keyword(s):

Dispersion Model ◽

Farming Systems ◽

Farming System ◽

Passive Samplers ◽

Ammonia Emission ◽

Specific Reference ◽

Ammonia Emissions ◽

Mean Values ◽

Po Valley ◽

Inverse Dispersion

Fertigation can be a suitable technique for utilizing digestate, minimizing nitrogen losses, and contributing to circularity within a farming system. For this purpose, digestate usually is first processed with a screw-press separator. However, further filtration is required to remove particles that could clog the nozzles of drip or sprinkling irrigation systems. Advanced filtration can be obtained using mechanical separation with screens having openings of 100- 300 μm. This operation can be another source of ammonia emission, but this aspect has not been adequately investigated. This study aimed to address this knowledge gap by evaluating the emissions from three different filtration systems for digestate. The study was conducted in three different farms located in Lombardy (Italy) using digestate to fertigate maize by drip irrigation (two farms) and pivot irrigation (one farm). Ammonia emissions were measured with passive samplers and the fluxes were examined using an inverse dispersion model implemented in Windtrax software. The emissions were measured both when the filtration systems were in operation and when they were switched off. Ammonia emissions (mean values between 375 and 876 μg NH3/m2/s) tended to increase during operation of the filtration systems. However, no significant differences were found in the emissions from active and inactive equipment on any of the farms. The emissions from the filtration systems were higher than from a storage tank (22-67 μg NH3/m2/s). However, the mean emissions amounted to only 0.3% of the nitrogen content of the digestate. These emissions can be considered irrelevant in the context of the whole management scheme for digestate. This work provides a first insight on ammonia emissions arising from advanced filtration of digestate, with specific reference to Po Valley farming systems. Further studies are required to improve knowledge about emissions from the entire digestate management process, including the treatments required for specific application techniques.

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VISUALISING URBAN AIR QUALITY USING AERMOD, CALPUFF AND CFD MODELS: A CRITICAL REVIEW

ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences ◽

10.5194/isprs-archives-xliv-4-w3-2020-355-2020 ◽

2020 ◽

Vol XLIV-4/W3-2020 ◽

pp. 355-363

Author(s):

N. Ridzuan ◽

U. Ujang ◽

S. Azri ◽

T. L. Choon

Keyword(s):

Air Quality ◽

Urban Area ◽

Air Pollutants ◽

Dispersion Model ◽

Ambient Air ◽

Urban Air Quality ◽

Urban Air ◽

Air Quality Modelling ◽

Modeling Tools ◽

Wide Range

Abstract. Degradation of air quality level can affect human’s health especially respiratory and circulatory system. This is because the harmful particles will penetrate into human’s body through exposure to surrounding. The existence of air pollution event is one of the causes for air quality to be low in affected urban area. To monitor this event, a proper management of urban air quality is required to solve and reduce the impact on human and environment. One of the ways to manage urban air quality is by modelling ambient air pollutants. So, this paper reviews three modelling tools which are AERMOD, CALPUFF and CFD in order to visualise the air pollutants in urban area. These three tools have its own capability in modelling the air quality. AERMOD is better to be used in short range dispersion model while CALPUFF is for wide range of dispersion model. Somehow, it is different for CFD model as this model can be used in wide range of application such as air ventilation in clothing and not specifically for air quality modelling only. Because of this, AERMOD and CALPUFF model can be classified in air quality modelling tools group whereas CFD modelling tool is classified into different group namely a non-specific modelling tool group which can be implemented in many fields of study. Earlier air quality researches produced results in two-dimensional (2D) visualization. But there are several of disadvantages for this technique. It cannot provide height information and exact location of pollutants in three-dimensional (3D) as perceived in real world. Moreover, it cannot show a good representation of wind movement throughout the study area. To overcome this problem, the 3D visualization needs to be implemented in the urban air quality study. Thus, this paper intended to give a better understanding on modeling tools with the visualization technique used for the result of performed research.

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Analysis of urban air quality in 6 European cities by lower cost sensors, Lagrangian urban dispersion modelling and traffic flow modelling: the TRAFAIR project

10.5194/egusphere-egu2020-13601 ◽

2020 ◽

Author(s):

Ohad Zivan ◽

Alessandro Bigi ◽

Giorgio Veratti ◽

José Antonio Souto González ◽

Lorena Marrodán ◽

...

Keyword(s):

Air Quality ◽

Traffic Flow ◽

Urban Area ◽

Lower Cost ◽

Dispersion Model ◽

Urban Air Quality ◽

Urban Air ◽

Electrochemical Cells ◽

Dispersion Modelling ◽

Traffic Data

Most of worldwide population lives in urban areas, demanding for air quality information with a high spatio-temporal resolution. The most promising approaches for estimating urban air quality within the complex urban topography are small sensor networks and simulation models.The TRAFAIR project focuses on understanding the role of traffic emissions on urban air quality by the combination of dispersion modelling, space- and time-resolved gas monitoring by lower cost sensors and realistic traffic flow rates by dynamic traffic model based on real time traffic data. Test cities of TRAFAIR are Modena, Florence, Pisa, Livorno, Zaragoza and Santiago de Compostela.Depending on the size of the urban area, from 6 to 13 sensors units are deployed across each city since August 2019, providing estimates of NO, NO2, CO and O3, along with RH and temperature. Metal oxide sensors are deployed in Tuscany (Florence, Pisa, Livorno) and electrochemical cells are used elsewhere. The units are calibrated on a regular basis by co-location at the air quality regulatory stations and subsequently deployed across the town to monitor several representative locations (e.g. Low Emission Zones, hospital surroundings). For each sensor the raw readings (e.g. mV for electrochemical cells) are collected and a regression model (e.g. Random Forest) is applied to derive a calibration function, exploiting the data from the regulatory stations during co-location periods; for instance in Modena, the first short-term calibration provided a model with a Mean Absolute Error between 5 &#8211; 6 ppb and 2 &#8211; 4 ppb for NO and NO2 respectively.The sensors are used for both real-time urban air quality mapping and to test and validate the 24hr forecast service of NOx by the microscale lagrangian dispersion model GRAL. The simulation domains, covering the urban area of each TRAFAIR city, have a horizontal resolution of 4 m and allow to account for the presence of buildings. The dispersion model mainly focuses on NOx by traffic emissions, although domestic heating will be also included in the analysis. Vehicular emissions are based either upon historical traffic data (e.g. induction loops), or upon previously available traffic flow simulation, or upon traffic pattern reconstruction using a traffic flow model followed by a cluster analysis to group streets with similar pattern.The final goal of the project is the development of a tool to support local policymakers and to inform citizenship about the quality of air and the impact of urban emission sources, particularly traffic. A secondary goal of the project is the development of a valuable QA/QC protocol for small sensor units and the optimization of the modelling chain for the forecast of traffic and domestic heating impact on local air quality at the urban scale.

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