Atmospheric Environment (v.42, #30)
Editorial board (i).
Inhable particulate matter from lime industries: Chemical composition and deposition in human respiratory tract by Ricardo H.M. Godoi; Darci M. Braga; Yaroslava Makarovska; Balint Alfoldy; Marco A.S. Carvalho Filho; Réne Van Grieken; Ana Flavia L. Godoi (7027-7033).
Air pollution caused by the lime production industry has become a serious problem with potential effects to human health, especially in developing countries. Colombo is a city included in the Metropolitan Region of Curitiba (capital of Paraná State) in South Brazil. In Colombo city, a correlation has been shown between the lime production and the number of persons who need respiratory treatment in a local hospital, indicating that the lime industry can cause deleterious health effects in the exposed workers and population. This research was conducted to deal firstly with the characterization of the size distribution and chemical compositions of particles emitted from lime manufacturing and subsequently to assess the deposition rate of inhaled dolomitic lime aerosol particles in the human respiratory tract. The elemental chemical composition and particle size of individual atmospheric particles was quantitatively elucidated, including low-Z components like C, N and O, as well as higher-Z elements, using automated electron probe microanalysis. Information concerning the bulk composition is provided by energy-dispersive X-ray detection. The majority of the respirable particulate matter identified was composed of aluminosilicates, Ca–Mg oxides, carbon-rich particles, mixtures of organic particles and Ca–Mg carbonates, soot and biogenic particles. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the human respiratory system were calculated, revealing the deposition of CaO·MgO at extrathoracic, tracheobronchial and pulmonary levels. The results of this study offer evidence to the threat of the fine and coarse particles emitted from dolomite lime manufacturing, allowing policy-makers to better focus their mitigation strategies in an effective way, as well as to the dolomite producers for the purpose of designing and/or implementing improved emission controls.
Keywords: Lime production; Single particles; Particle lung deposition; EPMA; EDXRF;
Using 137Cs and 40K to identify natural Saharan dust contributions to PM10 concentrations and air quality impairment in the Canary Islands by L. Karlsson; F. Hernandez; S. Rodríguez; M. López-Pérez; J. Hernandez-Armas; S. Alonso-Pérez; E. Cuevas (7034-7042).
Tenerife (Canary Islands) is often affected by Saharan mineral dust outbreaks. These events result in high PM10 concentrations in ambient air, well above the limiting values adopted by the European Union (Directive EU/1999/30). To comply with the EU Air Quality Directive, a quantitative proxy for the characterisation of high PM10 events is required. Furthermore, this proxy must be capable of differentiating natural sources (as defined by the Directive), such as Saharan mineral dust outbreaks, from other anthropogenic sources. In this study, we have analysed the time series of 137Cs, 40K and PM10 recorded at the island of Tenerife (2000–2006) in the Marine Boundary Layer (MBL), to test the possible usefulness of the two mentioned radiotracers as markers of Saharan mineral dust events. The results of the analysis showed that this is indeed the case for 137Cs and that there are, at least, two different sources of 40K concentrations in the collected atmospheric aerosol filters. While the detection of 137Cs in atmospheric aerosol filters could be directly associated with the arrival of low altitude (<2000 m.a.s.l.) dust intrusions to the study site, 40K concentrations could be associated, in most cases, with either low or high altitude (>2000 m.a.s.l) dust intrusions. Moreover, two different mechanisms of aerosol loading in the MBL were, also, identified with the mentioned radiotracers.Good correlations (R 2 > 0.6) were found between the three parameters when all the compiled data was considered. The correlation values increased to nearly 0.8 when only those samples that had 137Cs above detection limits were considered. The highest concentrations of 137Cs, 40K and PM10 were recorded in March 2004 in connection with a very intense low altitude Saharan dust intrusion. The results of this study, also, indicated that the 137Cs/40K ratio could be potentially useful to differentiate low from high altitude dust intrusions at this site.
Keywords: Radiotracers; Caesium-137; Potassium-40; PM10; Saharan dust; Air quality; Atmospheric aerosols; Back-trajectories; Dust intrusions;
Study on the acidification and pollution of precipitation based on a data set collected on a 0.5-mm precipitation basis by Masahide Aikawa; Takatoshi Hiraki; Jiro Eiho (7043-7049).
A precipitation data set collected on a 0.5-mm precipitation basis was studied. This made it possible to discern the temporal variation of component concentration in the precipitation event in detail. The parameters analyzed in this study were pH (i.e., H+ concentration), electric conductivity (EC), and SO4 2− and NO3 − concentrations. The H+ concentration was significantly correlated with NO3 − concentration, rather than SO4 2− concentration. On the other hand, the EC was more correlated with SO4 2− concentration than NO3 − concentration. Furthermore, the temporal variation of precipitation SO4 2− and NO3 − concentration in the longest precipitation event in one year corresponds more to that of suspended particulate matter concentration, than to SO2 and NO x (=NO + NO2) concentrations in the atmosphere. These findings strongly indicate that the acidification of precipitation was deeply related to acidic NO3 −-bearing compounds while the precipitation pollution was profoundly related to SO4 2−-bearing compounds, including sea salt particles which produce sea salt (ss-) SO4 2−.
Keywords: Acid rain; Air pollutant; Nitrate; Rainfall event; Sulfate; Suspended particulate matter (SPM);
A comparative and critical evaluation of odour assessment methods on a landfill site by Laura Capelli; Selena Sironi; Renato Del Rosso; Paolo Céntola; Massimiliano Il Grande (7050-7058).
This paper discusses the application of three different odour characterization techniques, i.e. chemical analyses, dynamic olfactometry and electronic noses, for the assessment of odour emissions from a landfill site. The results of the chemical analyses, which are useful to determine the chemical composition of odours, show no correlation with the odour concentration values measured by dynamic olfactometry. Olfactometric analyses enabled to measure odour concentration and thereby to quantify the sensory impact of odours. Finally, the continuous ambient air monitoring by electronic noses allowed to quantify the time percentage in which odours are detected at the landfill boundaries and at a receptor, which always turned out to be lower than 15%. This study represents a critical review of employing three different odour characterization methods for differing reasons on the same site, showing that, whilst the results don't necessarily correlate, they do have an intrinsic value, and therefore demonstrating the complexity of environmental odour measurement.
Keywords: Odour emissions; Electronic nose; Dynamic olfactometry; Odour concentration; Gas chromatography;
Simulating the impact of urban sprawl on air quality and population exposure in the German Ruhr area. Part I: Reproducing the base state by Koen De Ridder; Filip Lefebre; Stefan Adriaensen; Ute Arnold; Wolfgang Beckroege; Christine Bronner; Ole Damsgaard; Ivo Dostal; Jiri Dufek; Jacky Hirsch; Luc IntPanis; Zdenek Kotek; Thierry Ramadier; Annette Thierry; Stijn Vermoote; Annett Wania; Christiane Weber (7059-7069).
Compact city forms are associated with minimal consumption of land and energy, hence, they are often promoted as being the more sustainable thus preferred mode of urban development. In this context, numerical simulations were performed to evaluate the effect of urban sprawl on air quality and associated human exposure. Working on a highly urbanised area in the German Ruhrgebiet, models dealing with satellite data processing, traffic flows, pollutant emission and atmospheric dispersion were applied in an integrated fashion, under conditions representative of the urbanised area as it is today. A fair agreement was obtained between simulated and observed meteorological variables, as well as between simulated and observed concentrations of ozone and particulate matter. Simulated atmospheric pollution fields were found to closely reflect urbanisation patterns. In a companion paper [De Ridder, K., Lefebre, F., Adriaensen, S., Arnold, U., Beckroege, W., Bronner, C., Damsgaard, O., Dostal, I., Dufek, J., Hirsch, J., IntPanis, L., Kotek, Z., Ramadier, T., Thierry, A., Vermoote, S., Wania, A., Weber, C., 2008. Simulating the impact of urban sprawl on air quality and population exposure in the German Ruhr area. Part II: Development and evaluation of an urban growth scenario], the results of this base case simulation will be compared with those of a scenario simulation, designed to mimic urban sprawl, so as to allow the evaluation of the latter on air quality and associated human exposure.
Keywords: Urban sprawl; Traffic modelling; Air quality modelling;
Simulating the impact of urban sprawl on air quality and population exposure in the German Ruhr area. Part II: Development and evaluation of an urban growth scenario by Koen De Ridder; Filip Lefebre; Stefan Adriaensen; Ute Arnold; Wolfgang Beckroege; Christine Bronner; Ole Damsgaard; Ivo Dostal; Jiri Dufek; Jacky Hirsch; Luc IntPanis; Zdenek Kotek; Thierry Ramadier; Annette Thierry; Stijn Vermoote; Annett Wania; Christiane Weber (7070-7077).
The impact of uncontrolled urban growth (‘sprawl’) on air pollution and associated population exposure is investigated. This is done for the Ruhr area in Germany, by means of a coupled modelling system dealing with land use changes, traffic, meteorology, and atmospheric dispersion and chemistry. In a companion paper [De Ridder, K., Lefebre F., Adriaensen S., Arnold U., Beckroege W., Bronner C., Damsgaard O., Dostal I., Dufek J., Hirsch J., Int Panis L., Kotek Z., Ramadier T., Thierry A., Vermoote S., Wania A., Weber C., 2008. Simulating the impact of urban sprawl on air quality and population exposure in the German Ruhr area. Part I: reproducing the base state.], a description was given of the coupling of these models and of the validation of simulation results. In the present paper, a land use change scenario was implemented to mimic urban sprawl, relocating 12% of the urban population in the study domain to the green periphery. The resulting updated land use, population and employment density patterns were then used as input for traffic simulations, yielding an increase of total traffic volume by almost 17%. As a consequence, the domain-average simulated pollutant concentrations of ozone and particulate matter increased, though by a smaller amount, of approximately 4%. In a final step, population exposure to air pollution was calculated, both for the base case and the scenario simulations. A very slight domain-average exposure increase was found, of the order of a half percent. A compensating mechanism was identified, explaining this small figure. However, when stratifying the population into groups of individuals that were relocated to the urban periphery and those that were not, much larger exposure changes following urban sprawl emerged. Indeed, it was found that the relatively small proportion of relocated individuals benefited of a decrease of exposure to particulate matter by almost 13%, mainly because of their moving out of the most polluted areas; and that this came at the expense of an increase of exposure of 1.2% by the individuals not having moved.
Keywords: Urban sprawl; Air quality modelling; Human exposure;
Assessment and prediction of short term hospital admissions: the case of Athens, Greece by P. Kassomenos; C. Papaloukas; M. Petrakis; S. Karakitsios (7078-7086).
The contribution of air pollution on hospital admissions due to respiratory and heart diseases is a major issue in the health-environmental perspective. In the present study, an attempt was made to run down the relationships between air pollution levels and meteorological indexes, and corresponding hospital admissions in Athens, Greece.The available data referred to a period of eight years (1992–2000) including the daily number of hospital admissions due to respiratory and heart diseases, hourly mean concentrations of CO, NO2, SO2, O3 and particulates in several monitoring stations, as well as, meteorological data (temperature, relative humidity, wind speed/direction).The relations among the above data were studied through widely used statistical techniques (multivariate stepwise analyses) and Artificial Neural Networks (ANNs). Both techniques revealed that elevated particulate concentrations are the dominant parameter related to hospital admissions (an increase of 10 μg m−3 leads to an increase of 10.2% in the number of admissions), followed by O3 and the rest of the pollutants (CO, NO2 and SO2). Meteorological parameters also play a decisive role in the formation of air pollutant levels affecting public health. Consequently, increased/decreased daily hospital admissions are related to specific types of meteorological conditions that favor/do not favor the accumulation of pollutants in an urban complex. In general, the role of meteorological factors seems to be underestimated by stepwise analyses, while ANNs attribute to them a more important role. Comparison of the two models revealed that ANN adaptation in complicate environmental issues presents improved modeling results compared to a regression technique.Furthermore, the ANN technique provides a reliable model for the prediction of the daily hospital admissions based on air quality data and meteorological indices, undoubtedly useful for regulatory purposes.
Keywords: Air pollution; Hospital admissions; Meteorology; Artificial Neural Networks; Athens;
Development and validating procedure of a formula to calculate a minimum separation distance from piggeries and poultry facilities to sensitive receptors by Jacques Nicolas; Julien Delva; Pierre Cobut; Anne-Claude Romain (7087-7095).
A specific formula to calculate separation distance from piggeries and poultry facilities to sensitive receptor is developed for Walloon Region, in Belgium. The paper briefly presents the main principles of the formula and discusses more deeply the compatibility of the distance approach with odour units, odour rate and percentiles usually applied to assess the odour annoyance zones. A method of validation is presented and tested to adjust the different parameters of the formula to Belgian field reality. A total of 43 farms of which 21 piggeries and 22 poultry facilities are visited and, for each case, the distance calculated by the formula is compared to the one deduced from odour annoyance criterion (10 ou m−3 at 98th percentile). Validation work results in discussing the sensibility of different factors of the formula and especially in adjusting a fitting factor to match the absolute distances to real field annoyance impression. Conclusions show that both approaches – separation distance formula and percentile evaluation – are coherent. The validation method allows parameter adjustment but should need further refinements to examine separately piggeries and poultry facilities.
Keywords: Odour management; Setback distance; Atmospheric dispersion modelling; Pigs; Poultry;
Distribution and wet deposition fluxes of total and methyl mercury in Wujiang River Basin, Guizhou, China by Yanna Guo; Xinbin Feng; Zhonggen Li; Tianrong He; Haiyu Yan; Bo Meng; Junfang Zhang; Guangle Qiu (7096-7103).
Guizhou is one of the most seriously contaminated regions with mercury in China, but mercury deposition fluxes in this region have not been well studied. Concentrations and wet deposition fluxes of total mercury (THg) and methyl mercury (MeHg) were measured from January to December 2006 at 5 sites in Wujiang River Basin, Guizhou, China. Monthly-integrated samples were collected using bulk precipitation samplers. Samples were treated rigorously according to our trace metal protocol, and THg was analyzed by cold vapor atomic fluorescence spectrometry (CVAFS) and MeHg by aqueous phase ethylation, GC separation, and CVAFS detection. The annual volume-weighted mean concentration and wet deposition fluxes of THg and MeHg for 5 sites were 36.0 ng L−1 and 34.7 μg m−2 yr−1, and 0.19 ng L−1 and 0.18 μg m−2 yr−1 in 2006, respectively. The proportion of MeHg to THg ranged from 0.2% to 2.3%, with the mean value of 0.7%. The results also showed that each site had a similar seasonal trend for mercury concentration and wet deposition flux. The largest wet deposition fluxes of THg and MeHg occurred during the rainy season (May–October) when the rainfall was greater, whereas the highest concentrations of THg and MeHg appeared during winter months (December–February). The monthly concentrations of THg and MeHg negatively correlated well with the monthly precipitation depth (r 2 = 0.17 and 0.12), suggesting that scavenging of particle-bound mercury from the atmospheric is an important mechanism contribution to mercury in rain.
Keywords: Total mercury; Methyl mercury; Precipitation; Seasonal and spatial distribution; Wet deposition fluxes; Wujiang River Basin;
Ozone transport by mesoscale convective storms in western Senegal by Deanne D. Grant; Jose D. Fuentes; Marcia S. DeLonge; Stephen Chan; Everette Joseph; Paul Kucera; Seydi A. Ndiaye; Amadou T. Gaye (7104-7114).
During the rainy period of August and September 2006, a study was conducted to investigate the prevailing diurnal patterns of ozone in rural western Senegal. Ground-level ozone was continuously measured with gas analyzers. During selected days, ozone and atmospheric thermodynamic measurements were also made in the troposphere. Ground-level ozone exhibited diurnal variations in response to the local photochemical processes and vertical transport. Maximum ground-level ozone mixing ratios reached 30 parts per billion on a volume basis (ppbv) during 1200–1600 h, local time. Deviations from the expected diurnal ozone patterns were observed during most rainy days. The observed deviations were manifested as ozone increases which were associated with downdrafts of mesoscale convective storms. The magnitude of the ozone increases depended on the strength of convective velocities which exceeded 10 m s−1. Downdrafts increased the ground-level ozone by 10–30 ppbv. Based on field observation in Senegal and elsewhere, a conceptual model is presented to explain the influences of convective storms on the redistribution of ozone in the continental troposphere.
Keywords: Ozone; Convection; Dry deposition; Ozone fluxes; Boundary layer;
Dissolved organic carbon in rainwater from areas heavily impacted by sugar cane burning by C.H. Coelho; J.G. Francisco; R.F.P. Nogueira; M.L.A.M. Campos (7115-7121).
This work reports on rainwater dissolved organic carbon (DOC) from Ribeirão Preto (RP) and Araraquara over a period of 3 years. The economies of these two cities, located in São Paulo state (Brazil), are based on agriculture and related industries, and the region is strongly impacted by the burning of sugar cane foliage before harvesting. Highest DOC concentrations were obtained when air masses traversed sugar cane fields burned on the same day as the rain event. Significant increases in the DOC volume weighted means (VWM) during the harvest period, for both sites, and a good linear correlation (r = 0.83) between DOC and K (a biomass burning marker) suggest that regional scale organic carbon emissions prevail over long-range transport. The DOC VWMs and standard deviations were 272 ± 22 μmol L−1 (n = 193) and 338 ± 40 μmol L−1 (n = 80) for RP and Araraquara, respectively, values which are at least two times higher than those reported for other regions influenced by biomass burning, such as the Amazon. These high DOC levels are discussed in terms of agricultural activities, particularly the large usage of biogenic fuels in Brazil, as well as the analytical method used in this work, which includes volatile organic carbon when reporting DOC values. Taking into account rainfall volume, estimated annual rainwater DOC fluxes for RP (4.8 g C m−2 yr−1) and Araraquara (5.4 g C m−2 yr−1) were close to that previously found for the Amazon region (4.8 g C m−2 yr−1). This work also discusses whether previous calculations of the global rainwater carbon flux may have been underestimated, since they did not consider large inputs from biomass combustion sources, and suffered from a possible analytical bias.
Keywords: Brazil; Wet deposition; Carbon flux; Volatile organic carbon; Global carbon budget;
Comparison of two data assimilation methods for assessing PM10 exceedances on the European scale by Bruce Denby; Martijn Schaap; Arjo Segers; Peter Builtjes; Jan Horálek (7122-7134).
Two different data assimilation techniques have been applied to assess exceedances of the daily and annual mean limit values for PM10 on the regional scale in Europe. The two methods include a statistical interpolation method (SI), based on residual kriging after linear regression of the model, and Ensemble Kalman filtering (EnKF). Both methods are applied using the LOTOS-EUROS model. Observations for the assimilation and validation of the methods have been retrieved from the Airbase database using rural background stations only. For the period studied, 2003, 127 suitable stations were available. The LOTOS-EUROS model is found to underestimate PM10 concentrations by a factor of 2. This large model bias is found to be prohibitive for the effective use of the EnKF methodology and a bias correction was required for the filter to function effectively. The results of the study show that both methods provide significant improvement on the model calculations when compared to an independent set of validation stations. The total root mean square error of the daily mean concentrations of PM10 at the validation stations was reduced from 16.7 μg m−3 for the model to 9.2 μg m−3 using SI and to 13.5 μg m−3 using EnKF. Similarly, correlation (R 2) is also significantly improved from 0.21 for the model to 0.66 using SI and 0.41 using EnKF. Significant improvement in the annual mean and number of exceedance days of PM10 is also seen. In addition to the validation of the methods, maps of exceedances and their associated uncertainty are presented. The most effective methodology is found to be the statistical interpolation method. The application of EnKF is novel and yields promising results, although its application to PM10 still needs to be improved.
Keywords: Data assimilation; Air quality; Uncertainty; Ensemble Kalman filter; Kriging;
Chloroform, carbon tetrachloride and methyl chloroform fluxes in southern California ecosystems by Robert C. Rhew; Benjamin R. Miller; Ray F. Weiss (7135-7140).
Chloroform (CHCl3), carbon tetrachloride (CCl4), and methyl chloroform (CH3CCl3) are important carriers of chlorine to the stratosphere and account for an estimated 15% of the total organic chlorine in the troposphere, roughly equivalent to chlorine load due to methyl chloride (CH3Cl). The tropospheric burden of chlorine has declined since 1994, largely due to the restriction of CH3CCl3 and CCl4 use as specified by the Montreal Protocol. However, few field studies have been conducted on the terrestrial-atmosphere exchange of these chlorinated hydrocarbons, leading to uncertainties about the natural cycling of these trace gases. This work shows the results of 75 flux measurements conducted in a variety of southern California ecosystems, including coast sagebrush, chamise chaparral, creosote bush scrub, shoreline, and coastal salt marsh. We find no evidence of a significant soil sink in these ecosystems but rather a small net source of CHCl3 and possibly CCl4.
Keywords: Trichloromethane; 1,1,1-Trichloroethane; Tetrachloromethane; Shrubland; Salt marsh;
Deposition rates of fungal spores in indoor environments, factors effecting them and comparison with non-biological aerosols by Hussein Kanaani; Megan Hargreaves; Zoran Ristovski; Lidia Morawska (7141-7154).
Particle deposition indoors is one of the most important factors that determine the effect of particle exposure on human health. While many studies have investigated the particle deposition of non-biological aerosols, few have investigated biological aerosols and even fewer have studied fungal spore deposition indoors. The purpose of this study was, for the first time, to investigate the deposition rates of fungal particles in a chamber of 20.4 m3 simulating indoor environments by: (1) releasing fungal particles into the chamber, in sufficient concentrations so the particle deposition rates can be statistically analysed; (2) comparing the obtained deposition rates with non-bioaerosol particles of similar sizes, investigated under the same conditions; and (3) investigating the effects of ventilation on the particle deposition rates. The study was conducted for a wide size range of particle sizes (0.54–6.24 μm), at three different air exchange rates (0.009, 1.75 and 2.5 h−1). An Ultraviolet Aerodynamic Particle Sizer Spectrometer (UVAPS) was used to monitor the particle concentration decay rate. The study showed that the deposition rates of fungal spores (Aspergillus niger and Penicillium species) and the other aerosols (canola oil and talcum powder) were similar, especially at very low air exchange rates (in the order of 0.009). Both the aerosol and the bioaerosol deposition rates were found to be a function of particle size. The results also showed increasing deposition rates with increasing ventilation rates, for all particles under investigation. These conclusions are important in understanding the dynamics of fungal spores in the air.
Keywords: Deposition rate; Air exchange rates (AER); Fungal particles; Fluorescent percentage; Ventilation rate;
Developing a spatially and temporally resolved emission inventory for photochemical modeling in the City of Cape Town and assessing its uncertainty by Miles Sowden; Eugene Cairncross; Gary Wilson; Mark Zunckel; Elena Kirillova; Vis Reddy; Sibbele Hietkamp (7155-7164).
In an urban environment where reactive pollutants are emitted, it is critically important that atmospheric chemistry be considered in modeling and air quality management including the evaluation of secondary pollutants such as ozone. This may be achieved through photochemical modeling, which is reliant on detailed, grid resolved emissions inventories. The US-EPA's approved Emissions Processing System (EPS) is used to develop a temporally and spatially resolved emissions inventory for the City of Cape Town for use in the Dynamic Air Pollution Prediction System (DAPPS). Included in this inventory are large and small point sources, mobile sources, and emissions from residential fuel burning and biogenic sources. Large point sources are usually well defined unlike the other source types that can have large uncertainties associated with them. In these circumstances, surrogate data are used to estimate emission rates. The FRamework for the Assessment of Uncertainties in Large-scale Emission INventories (FRAULEIN) approach to assessing uncertainty in the emissions inventory is adapted for DAPPS. A reasonable level of confidence exists for the characterization of large point sources but the two biggest source contributors namely vehicle and biogenic emissions, needs improvement.
Keywords: DAPPS; CAMx; EPS; Photochemical modeling; South Africa; Air quality management; Uncertainty assessment; FRAULEIN;
Tropospheric NO2 columns over East Central China: Comparisons between SCIAMACHY measurements and nested CMAQ simulations by Chune Shi; H.J.S. Fernando; Zifa Wang; Xingqin An; Qizhong Wu (7165-7173).
Tropospheric NO2 vertical column densities over East Central China (ECC) simulated with a regional air quality model are compared with those measured by the remote sensor SCIAMACHY (SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY). A 3D Eulerian air quality model (Models-3/CMAQ) and a best available emission inventory are employed in the simulations. The objectives are to delve into (i) the suitability of the emission inventory employed, (ii) the reliability of SCIAMACHY observations over ECC, and (iii) the role of model resolution on predictions. The predicted NO2 concentrations are integrated from the bottom to the model top and converted from the model grid to satellite pixel bases. The model reproduces the spatial distribution of SCIAMACHY-observed NO2 vertical column densities satisfactorily with a correlation coefficient of about 0.76, but with a large normalized mean bias ∼−60%. The latter bias is ascribed to the sharp increase of emissions that have occurred in ECC owing to rapid industrialization ever since the compilation of the emission inventory. When the model grid size is larger than the size of a satellite pixel, a decrease of grid size improves the CMAQ predictions when compared with SCIAMACHY, although higher resolutions in general do not necessarily improve CMAQ predictions. A critical cloud fraction of 0.2 is found to give the best comparisons between SCIAMACHY data and simulations.
Keywords: Tropospheric NO2 columns; SCIAMACHY; East central China; Models-3/CMAQ;
Lidar ceilometer observations and modeling of a fireworks plume in Vancouver, British Columbia by Derek van der Kamp; Ian McKendry; May Wong; Roland Stull (7174-7178).
Observations of a plume emanating from a 30-min duration pyrotechnic display with a lidar ceilometer are described for an urban setting in complex, coastal terrain. Advection of the plume across the ceilometer occurred at a mean height of 250 m AGL. The plume traveled downwind at ∼3 m s−1, and at a distance of 8 km downwind, was ∼100 m in vertical thickness with particulate matter (PM) concentrations of order 30–40 μg m−3. Surface PM observations from surrounding urban monitoring stations suggest that the plume was not mixed to ground over the urban area. Plume trajectories at ∼250 m simulated by three numerical models all traveled to the northeast of the ceilometer location. Horizontal plume dispersion estimates suggest that the model trajectories were too far north to accommodate the likely lateral plume spread necessary to explain the ceilometer observations. This poor agreement between near surface observations and model output is consistent with previous mesoscale model validations in this region of complex urbanized terrain, and suggests that despite improvements in mesoscale model resolution, there remains an urgent need to improve upstream initial conditions over the Pacific Ocean, data assimilation over complex terrain, the representation of urban areas in mesoscale models, and to further validate such models for nocturnal applications in complex settings.
Keywords: Fireworks; Pyrotechnical display; Plume trajectories; Mesoscale model validation;
Variation of particle concentrations and environmental noise on the urban neighbourhood scale by Stephan Weber; Tom Litschke (7179-7183).
Particulate air pollution and environmental noise received increased attention within the environmental health community during recent years due to their potential impacts on human health. In this study the spatio-temporal variation of noise and particles was estimated by a short set of mobile measurements within an urban neighbourhood in Essen, Germany. Particle concentrations (PM1 and PMcoarse = PM10 − PM1) were measured by an optical particle counter continuously along the measurement route while environmental noise was measured at fixed points on the same route. Additionally, wind and turbulence parameters were gathered above rooftop height and within an urban street canyon.The spatial distribution of noise was very homogeneous while the distribution of particle concentrations turned out to be rather inhomogeneous. The spatial correlation between noise and particles was found to be poor for PMcoarse during all measurements. However, for PM1 and noise a moderate positive correlation (r ∼ 0.5) emerged under conditions of weak turbulent atmospheric mixing. The spatio-temporal covariation between particles and noise is believed to be more evident for ultrafine (<100 nm) particles.
Keywords: Urban; Aerosol; Turbulence; Microscale; Neighbourhood; Noise;