Direct measurements and parameterisation of aerosol flux, concentration and emission velocity above a city

Dorsey, J. R.; Nemitz, E.; Gallagher, Martin; Fowler, D.; Bower, Keith; Beswick, K.M.

doi:10.1016/s1352-2310(01)00526-x

Cited by 106 publications

(86 citation statements)

References 16 publications

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“…While frequently applied to CO 2 and other gas phase species, the application of the eddy covariance approach to aerosols has been limited by the stringent instrumental requirements: measurements must not only be portable and free of interference, but they must also be fast and sensitive enough to capture fluctuations on the time scale of flux-carrying turbulent eddies (≥5 Hz). Fluxes of total or size-resolved aerosol number (without chemical information) have been performed for some time (e.g., Katen et al, 1985;Sievering, 1987;Buzorius et al, 1998;Dorsey et al, 2002;Mårtensson et al, 2006;Vong et al, 2010). However, total and chemically-resolved particle mass fluxes have lagged behind because most instruments measuring mass or aerosol chemical composition are far from meeting the rigorous requirements for EC, and most chemically-resolved aerosol flux measurements have been indirect with slower time resolution approaches (e.g., Nemitz et al, 2004b;Trebs et al, 2006;Myles et al, 2007;Thomas et al, 2009;Wolff et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically resolved aerosol fluxes

et al. 2011

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Abstract.Although laboratory studies show that biogenic volatile organic compounds (VOCs) yield substantial secondary organic aerosol (SOA), production of biogenic SOA as indicated by upward fluxes has not been conclusively observed over forests. Further, while aerosols are known to deposit to surfaces, few techniques exist to provide chemically-resolved particle deposition fluxes. To better constrain aerosol sources and sinks, we have developed a new technique to directly measure fluxes of chemicallyresolved submicron aerosols using the high-resolution timeof-flight aerosol mass spectrometer (HR-AMS) in a new, fast eddy covariance mode. This approach takes advantage of the instrument's ability to quantitatively identify both organic and inorganic components, including ammonium, sulphate and nitrate, at a temporal resolution of several Hz. The new approach has been successfully deployed over a temperate ponderosa pine plantation in California during the BEARPEX-2007 campaign, providing both total and chemically resolved non-refractory (NR) PM 1 fluxes. Average deposition velocities for total NR-PM 1 aerosol at noon were 2.05 ± 0.04 mm s −1 . Using a high resolution measurement of the NH

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Section: Introductionmentioning

confidence: 99%

Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically resolved aerosol fluxes

et al. 2011

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“…Much of this uncertainty can be attributed to the large variety of different source categories which contribute to urban VOC emissions, which can be difficult to characterise and validate. Rather than taking a "bottom-up" inventory approach, an alternative is to make direct micrometeorologically based measurements which can integrate observations of wind speed and scalar concentrations to give a city-wide estimate of pollutant emission rates Dorsey et al, 2002;Velasco et al, 2005;Martin et al, 2008;Famulari et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Mixing ratios and eddy covariance flux measurements of volatile organic compounds from an urban canopy (Manchester, UK)

et al. 2009

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Abstract. Mixing ratios and fluxes of six selected volatile organic compounds (VOCs) were measured above the city of Manchester (UK) during the summer of 2006. A proton transfer reaction-mass spectrometer was used for the measurement of mixing ratios, and fluxes were calculated from these using both the disjunct and the virtual disjunct eddy covariance techniques. The two flux systems, which operated in alternate half hours, showed good agreement, with R 2 values ranging between 0.74 and 0.9 for the individual analytes. On average, fluxes measured in the disjunct mode were approximately 20% lower than those measured in the virtual mode. This difference is due to both the dampening of the VOC signal by the disjunct flux sampler and carry over from one sample to the next. Correcting for these effects reduced the difference to less than 7%. Observed fluxes are thought to be largely controlled by anthropogenic sources, with vehicle emissions the major contributor. However, both evaporative and biogenic emissions may account for some of the VOCs present. Concentrations and fluxes of the oxygenated compounds were highest on average, ranging between 0.15 to 1 mg m −2 h −1 ; the fluxes of aromatic compounds were lower, between 0.12 to 0.28 mg m −2 h −1 . The observed fluxes were up-scaled to give city wide emission estimates for each compound and the results compared to estimates made by the National Atmospheric Emission Inventory (NAEI) for the same flux footprint. Fluxes of toluene and benzene compared most closely differing by approximately 50%, while in contrast the oxygenated fluxes were found to be between 3.6-6.3 times larger than the annual average predicted by the NAEI.

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“…The reported correlations with TA and u * as expected were the strongest whilst that with sensible heat, H was the weakest. For relatively unstable conditions a positive correlation was found between the sensible heat flux and particle number flux but correlation with local stability, ζ , was poor (also reported by Dorsey et al, 2002).…”

Section: Linking Aerosol Dispersion In Urban Canyons To Neighbourhoodmentioning

confidence: 63%

“…The question that must be considered is whether micrometeorological tower flux measurements above cities can be useful in describing the net ventilation behaviour of canyons with respect to aerosol fluxes. There have been several field studies of neighbourhoodscale aerosol emissions recently, Dorsey et al (2002); Martensson et al (2006); Martin et al (2009). These have attempted to investigate the relationship between F net as a function of source parameters such as traffic activity, TA, and meteorological factors including wind speed, turbulence, atmospheric stability/and or sensible heat flux.…”

Section: Linking Aerosol Dispersion In Urban Canyons To Neighbourhoodmentioning

confidence: 99%

“…In most cases the studies found strong positive correlation between F net and some of these factors (generally they show a weak dependence with traditional atmospheric stability parameters). Dorsey et al (2002) proposed a parameterisation of the form F net = Ae 1.6T A , where A is a constant, TA is the traffic activity (vehicles/s) and F net is (#particles/cm 2 /s). They also derived a relationship between F net in terms of the atmospheric stability parameter, ζ = −(z m − d)/L (where z m is the measurement height, d the urban canopy zero plane displacement and L the Monin-Obukov length which parameterises the buoyancy to shear driven scales of motion, and is given by L = −…”

Section: Linking Aerosol Dispersion In Urban Canyons To Neighbourhoodmentioning

confidence: 99%

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Linking urban aerosol fluxes in street canyons to larger scale emissions

et al. 2010

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Abstract. In this study we investigate ultrafine particle (UFP) fluxes using a first order eddy viscosity turbulence closure Computational Fluid Dynamics (CFD) model and determine the different factors that influence emissions of UFP into the urban boundary layer. Both vertical turbulent fluxes as well as the fluxes due to mean circulatory flow are shown to contribute to the overall ventilation characteristics of street canyons. We then derive a simple parameterised numerical prediction model for canyon top UFP venting which is then compared with tower based micrometeorological flux measurements obtained during the REPARTEE & CityFlux field experiments.

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Direct measurements and parameterisation of aerosol flux, concentration and emission velocity above a city

Cited by 106 publications

References 16 publications

Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically resolved aerosol fluxes

Eddy covariance measurements with high-resolution time-of-flight aerosol mass spectrometry: a new approach to chemically resolved aerosol fluxes

Mixing ratios and eddy covariance flux measurements of volatile organic compounds from an urban canopy (Manchester, UK)

Linking urban aerosol fluxes in street canyons to larger scale emissions

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