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Dispersion and Transformation of Traffic Exhaust Particles in the Urban Atmosphere

Ketzel, Matthias LU (2004)
Abstract (Swedish)
Popular Abstract in Swedish

Ämnet för denna avhandling är luftkvalitet i stadsmiljöer. Efter det att utsläppen till luft från industrier och produktion av värme och kraft har minskat betydligt över de senaste årtiondena framstår trafiken alltmer som en dominerande källa till luftföroreningar i städer, och utgör ett hot mot människors hälsa.



De största hälsoeffekterna orsakade av trafikens utsläpp antas numera vara kopplade till de luftburna partiklarna (aerosolpartiklar). Ett stort antal studier har visat att förhöjda partikelhalter orsakar ökad dödlighet och sjuklighet, både akut (inom några dagar efter exponering) och kronisk (efter långtidsexponering). Sjukligheten och dödligheten förorsakas av... (More)
Popular Abstract in Swedish

Ämnet för denna avhandling är luftkvalitet i stadsmiljöer. Efter det att utsläppen till luft från industrier och produktion av värme och kraft har minskat betydligt över de senaste årtiondena framstår trafiken alltmer som en dominerande källa till luftföroreningar i städer, och utgör ett hot mot människors hälsa.



De största hälsoeffekterna orsakade av trafikens utsläpp antas numera vara kopplade till de luftburna partiklarna (aerosolpartiklar). Ett stort antal studier har visat att förhöjda partikelhalter orsakar ökad dödlighet och sjuklighet, både akut (inom några dagar efter exponering) och kronisk (efter långtidsexponering). Sjukligheten och dödligheten förorsakas av komplikationer både i luftvägarna och i hjärt- kärlsystemet. Detta har föranlett att nya strängare gränsvärden för partikelhalter har antagits inom EU.



Denna avhandling syftar till att beskriva de processer som styr halterna av partiklar från trafiken i stadsmiljöer och omgivande landsbygd, med tonvikt på de minsta partiklarna med en diameter under en mikrometer. I detta storleksintervall återfinns en övervägande del av antalet aerosolpartiklar.



Med en kombination av mätningar och modeller undersöks hur dessa partiklar bildas, omvandlas och slutligen deponeras, samt hur deras storleksfördelning varierar i tid och rum. Resultaten kan användas för att göra uppskattningar av trafikens inverkan på människors hälsa, och utgör ett verktyg för att studera effekten av olika åtgärder som syftar till att minska trafikens utsläpp. (Less)
Abstract
Ultrafine particles, their sources and fate in the atmosphere are currently key issues in atmospheric research owing to concern about their effects on human health and global climate. Traffic emissions are a dominating source of ultrafine particles, especially in urban areas. After release into the atmosphere, the particles are subjected to complex dilution and transformation processes that are often treated in aerosol dynamics and dispersion models to better understand observations and to make predictions or scenario calculations for future situations.



This thesis contributes to the validation and the refinement of existing urban dispersion models and their extension towards a prediction of particle size distributions.... (More)
Ultrafine particles, their sources and fate in the atmosphere are currently key issues in atmospheric research owing to concern about their effects on human health and global climate. Traffic emissions are a dominating source of ultrafine particles, especially in urban areas. After release into the atmosphere, the particles are subjected to complex dilution and transformation processes that are often treated in aerosol dynamics and dispersion models to better understand observations and to make predictions or scenario calculations for future situations.



This thesis contributes to the validation and the refinement of existing urban dispersion models and their extension towards a prediction of particle size distributions. By analysing measurements of particle and gaseous pollutants and by application of various dispersion and aerosol dynamics models, the work aims at identifying and exploring the relevant processes that should be included in practical air pollution models for particles.



The relevance of the turbulence produced by the vehicle movements for the dispersion inside a street canyon has been shown in field data and a method to incorporate this effect into results from numerical models and wind tunnel measurements has been developed. Dispersion models of different complexity are applied to real-world situations and compared with field measurements and wind tunnel experiments.



Measurements of ultrafine particle size distribution at kerbside, urban, near-city and rural locations in the Copenhagen area are analysed. They document the temporal and spatial variation of the particle number and mass concentration and can clearly separate the different contributions from the local street traffic, the urban and regional sources. Particle number emission factors per average vehicle and kilometer driven were estimated for typical urban conditions in Denmark.



This thesis further investigates the time scales of various dynamic processes during the evolution of the particle size distribution from its emission from a vehicle exhaust pipe through its dilution at kerbside and urban level. We identify the spatial or temporal scales under which the discussed processes are important. The Multi-plume Aerosol dynamics and Transport (MAT) model has been developed to study the dynamics of the particle size distribution in an urban environment. The model used a new vertical dispersion scheme that is coupled to an existing aerosol dynamics model. The model was tested and applied to measurements in the Copenhagen area. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Kerminen, Veli-Matti, Finnish Meteorological Institute, Helsinki
organization
publishing date
type
Thesis
publication status
published
subject
keywords
condensation, deposition, dilution, particle size distribution, plume model, street canyon, traffic pollution, urban environment, turbulence, aerosol dynamics modelling, coagulation, Physics, Fysik, Fysicumarkivet A:2004:Ketzel
pages
139 pages
publisher
Nuclear Physics (Faculty of Technology)
defense location
Lecture hall B, Department of Physics, Lund Institute of Technology
defense date
2004-05-28 13:15
external identifiers
  • Other:ISRN: LUTFD2/(TFKF-1030)/1-139/(2004)
ISBN
91-628-5992-7
language
English
LU publication?
yes
id
f6bb1276-80e8-4ee8-825c-ad019ee9433d (old id 21768)
date added to LUP
2007-05-28 14:37:45
date last changed
2016-09-19 08:45:06
@misc{f6bb1276-80e8-4ee8-825c-ad019ee9433d,
  abstract     = {Ultrafine particles, their sources and fate in the atmosphere are currently key issues in atmospheric research owing to concern about their effects on human health and global climate. Traffic emissions are a dominating source of ultrafine particles, especially in urban areas. After release into the atmosphere, the particles are subjected to complex dilution and transformation processes that are often treated in aerosol dynamics and dispersion models to better understand observations and to make predictions or scenario calculations for future situations.<br/><br>
<br/><br>
This thesis contributes to the validation and the refinement of existing urban dispersion models and their extension towards a prediction of particle size distributions. By analysing measurements of particle and gaseous pollutants and by application of various dispersion and aerosol dynamics models, the work aims at identifying and exploring the relevant processes that should be included in practical air pollution models for particles.<br/><br>
<br/><br>
The relevance of the turbulence produced by the vehicle movements for the dispersion inside a street canyon has been shown in field data and a method to incorporate this effect into results from numerical models and wind tunnel measurements has been developed. Dispersion models of different complexity are applied to real-world situations and compared with field measurements and wind tunnel experiments.<br/><br>
<br/><br>
Measurements of ultrafine particle size distribution at kerbside, urban, near-city and rural locations in the Copenhagen area are analysed. They document the temporal and spatial variation of the particle number and mass concentration and can clearly separate the different contributions from the local street traffic, the urban and regional sources. Particle number emission factors per average vehicle and kilometer driven were estimated for typical urban conditions in Denmark.<br/><br>
<br/><br>
This thesis further investigates the time scales of various dynamic processes during the evolution of the particle size distribution from its emission from a vehicle exhaust pipe through its dilution at kerbside and urban level. We identify the spatial or temporal scales under which the discussed processes are important. The Multi-plume Aerosol dynamics and Transport (MAT) model has been developed to study the dynamics of the particle size distribution in an urban environment. The model used a new vertical dispersion scheme that is coupled to an existing aerosol dynamics model. The model was tested and applied to measurements in the Copenhagen area.},
  author       = {Ketzel, Matthias},
  isbn         = {91-628-5992-7},
  keyword      = {condensation,deposition,dilution,particle size distribution,plume model,street canyon,traffic pollution,urban environment,turbulence,aerosol dynamics modelling,coagulation,Physics,Fysik,Fysicumarkivet A:2004:Ketzel},
  language     = {eng},
  pages        = {139},
  publisher    = {ARRAY(0xaa1d7b8)},
  title        = {Dispersion and Transformation of Traffic Exhaust Particles in the Urban Atmosphere},
  year         = {2004},
}