Determinants of spatial variability of air pollutant concentrations in a street canyon network measured using a mobile laboratory and a drone

Järvi, Leena; Kurppa, Mona; Kuuluvainen, Heino; Rönkkö, Topi; Karttunen, Sasu; Balling, Anna; Timonen, Hilkka; Niemi, Jarkko V.; Pirjola, Liisa

doi:10.1016/j.scitotenv.2022.158974

Cited by 26 publications

(15 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The street consists of two pavements, six lanes, and two tramlines lined with trees in the middle, giving a total width of 42 m. The height of surrounding buildings is 16–19 m leading to an average height-to-width ratio (H/W) of 0.45. Perpendicular wind directions allow the formation of a street canyon vortex, but the low H/W ratio is not ideal for vortex formation. Especially in low wind speed conditions, the vortex may play a minor role in the dispersion compared to the turbulent mixing caused by traffic .…”

Section: Methodsmentioning

confidence: 99%

“…25 The pollution levels are highest at the street level addressing well the direct effects of traffic. The site and its air flow patterns are described in more detail by Jarvi et al, 24 Kuuluvainen et al, 25 and Olin et al 26 The ambient temperature during the measurements varied from 3.2 to 28.1 °C with a relatively cold and humid first 2 weeks followed by a warm and dry rest of the month. Daily mean, minimum, and maximum values for temperature and relative humidity are presented in Figure S4.…”

Section: Measurement Site and Conditionsmentioning

confidence: 99%

See 1 more Smart Citation

Sub-23 nm Particles Dominate Non-Volatile Particle Number Emissions of Road Traffic

Lintusaari

Kuuluvainen

Vanhanen³

et al. 2023

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

Ultrafine particles (<100 nm) in urban air are a serious health hazard not yet fully understood. Therefore, particle number concentration monitoring was recently included in the WHO air quality guidelines. At present, e.g., the EU regulates particle number only regarding the emissions of solid particles larger than 23 nm emitted by vehicles. The aim of this study was to examine the non-volatile fraction of sub-23 nm particles in a trafficinfluenced urban environment. We measured the number concentration of particles larger than 1.4, 3, 10, and 23 nm in May 2018. Volatile compounds were thermally removed in the sampling line and the line losses were carefully determined. According to our results, the sub-23 nm particles dominated the non-volatile number concentrations. Additionally, based on the determined particle number emission factors, the traffic emissions of non-volatile sub-10 nm particles can be even 3 times higher than those of particles larger than 10 nm. Yet, only a fraction of urban sub-10 nm particles consisted of non-volatiles. Thus, while the results highlight the role of ultrafine particles in the traffic-influenced urban air, a careful consideration is needed in terms of future particle number standards to cover the varying factors affecting measured concentrations.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Measurement Site and Conditionsmentioning

confidence: 99%

Sub-23 nm Particles Dominate Non-Volatile Particle Number Emissions of Road Traffic

Lintusaari

Kuuluvainen

Vanhanen³

et al. 2023

Environ. Sci. Technol.

Self Cite

View full text Add to dashboard Cite

show abstract

“…Simulation time of the model runs is separated into three parts: spin-up, precursor and main run (Figure 2). The main run of all modelled processes including SALSA covers the time period 07:00 -09:15 UTC+3, which was chosen as observations from an intensive observational campaign of local air quality are available for model evaluation (Järvi et al, 2023). Before the main run, a precursor run to initialise flow and turbulence (06:00 -07:00 UTC+3) is performed (Kurppa et al, 2020).…”

Section: Initialisationmentioning

confidence: 99%

“…During the measurement campaign, observations with a mobile laboratory Sniffer (Pirjola et al, 2004) and a drone were conducted (Järvi et al, 2023). The mobile laboratory measured N tot using a Condensation Particle Counter (CPC, TSI 3776, TSI Ltd, USA) and a 2-meter air temperature using a temperature and humidity probe (HMP45A, Vaisala Oyj, Finland) with a 1-s resolution.…”

Section: Observationsmentioning

confidence: 99%

“…The LES model PALM (Maronga et al, 2020) will be used in the simulations as it allows for realistic description of the urban surface and aerosol dynamics, and it can be coupled with the radiation module RRTMG (Rapid Radiative Transfer Model for Global models, Krč et al, 2021) to account for radiative interaction. Model outputs will be compared against LDSA concentrations of aerosol particles measured using a drone, and total particle number concentration and air temperature measured using a mobile laboratory (Järvi et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of radiation interaction and aerosol processes on ventilation and aerosol concentrations in a real urban neighbourhood in Helsinki

Strömberg

Li²,

Kurppa³

et al. 2023

Preprint

View full text Add to dashboard Cite

Abstract. Large eddy simulation (LES) provides an optimal tool to examine air pollutant concentrations at high temporal and spatial resolutions within urban neighborhoods. The local mixing conditions are to a large extent a result of building morphology and thermal conditions impacting mechanically and thermally driven turbulence. However, the impact of thermal conditions on local air pollutant concentrations in real urban environments is not well understood nor the importance of including thermal processes in LES. Furthermore, LES of aerosol particle concentrations in urban areas rarely include aerosol processes, but rather aerosols are treated as passive scalars. The aim of this study is to examine the importance of radiative heating and aerosol processes in simulating local aerosol particle concentrations in a wide street canyon and its surroundings in Helsinki under morning rush hour with calm wind conditions using the LES model PALM. The model outputs are evaluated against mobile laboratory measurements of air temperature and total particle number concentration (Ntot), and drone measurements of lung deposited surface area (LDSA). The inclusion of radiation interaction in LES has a significant impact on simulated near surface temperatures in our study domain increasing them on average by 3.8 °C from 8.6 °C to 12.4 °C. The thermal processes further strengthen the flow field, and enhance the ventilation of air pollutants from the street canyon by altering the canyon vortex. The enhanced ventilation reduces the pedestrian level (4 m) Ntot by 53 %. The reduction of Ntot due to aerosol processes is smaller, only 18 %. Aerosol processes have a larger effect in the smallest particle range, decreasing particle concentrations below 10 nm by up to 2.5 orders of magnitude whereas radiation interaction is more important in the larger particle range. Aerosol processes have a stronger impact than ventilation on LDSA, whereas radiation interaction shows a larger decrease in PM2.5 than in other aerosol metrics. The inclusion of radiation interaction in PALM improves the modelled near-surface temperatures and Ntot when compared to mobile laboratory measurements reducing the bias between the modelled and measured temperatures from -3.9 °C to +0.2 °C, and concentrations from +98 % to -13 %. With both aerosol and radiation interaction on, the underestimation was 16 %, which might be due to overestimation of the ventilation. The results show how inclusion of radiative interaction, and to a lesser extent aerosol processes, on LES are important for realistic simulation of near surface aerosol particle concentrations. This particularly in a calm wind situation such as modelled in this study.

show abstract

Effects of arcade design on wind and thermal environment inside an idealized 2D urban canyon with realistic solar heating

Hang,

Li,

et al. 2024

Building and Environment

View full text Add to dashboard Cite

Determinants of spatial variability of air pollutant concentrations in a street canyon network measured using a mobile laboratory and a drone

Cited by 26 publications

References 39 publications

Sub-23 nm Particles Dominate Non-Volatile Particle Number Emissions of Road Traffic

Sub-23 nm Particles Dominate Non-Volatile Particle Number Emissions of Road Traffic

Effect of radiation interaction and aerosol processes on ventilation and aerosol concentrations in a real urban neighbourhood in Helsinki

Effects of arcade design on wind and thermal environment inside an idealized 2D urban canyon with realistic solar heating

Contact Info

Product

Resources

About