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  • 1.
    Amorim, Jorge Humberto
    et al.
    SMHI, Research Department, Air quality.
    Valente, J.
    Cascao, P.
    Ribeiro, L. M.
    Viegas, D. X.
    Ottmar, R.
    Miranda, A. I.
    Near-source grid-based measurement of CO and PM2.5 concentration during a full-scale fire experiment in southern European shrubland2016In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 145, p. 19-28Article in journal (Refereed)
  • 2.
    Andersson, Camilla
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Johansson, Christer
    Population exposure and mortality due to regional background PM in Europe - Long-term simulations of source region and shipping contributions2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 22-23, p. 3614-3620Article in journal (Refereed)
    Abstract [en]

    This paper presents the contribution to population exposure (PE) of regional background fine primary (PPM(2.5)) and secondary inorganic (SIA) particulate matter and its impact on mortality in Europe during 1997-2003 calculated with a chemistry transport model. Contributions to concentrations and PE due to emissions from shipping, Western (WEU), Eastern (EEU), and Northern Europe are compared. WEU contributes about 40% to both PPM(2.5) and SIA concentrations, whereas the EEU contribution to PPM(2.5) is much higher (43% of total PPM(2.5)) than to SIA (29% of total SIA). The population weighted average concentration (PWC) of PPM(2.5) is a factor of 2.3 higher than average (non-weighted) concentrations, whereas for SIA the PWC is only a factor 1.6 higher. This is due to PPM(2.5) concentrations having larger gradients and being relatively high over densely populated areas, whereas SIA is formed outside populated areas. WEU emissions contribute relatively more than EEU to PWC and mortality due to both PPM(2.5) and SIA in Europe. The number of premature deaths in Europe is estimated to 301000 per year due to PPM(2.5) exposure and 245 000 due to SIA, despite 3.3 times higher average SIA concentrations. This is due to population weighting and assumed (and uncertain) higher relative risk of mortality for PPM(2.5) components (2.8 times higher RR for PPM(2.5)). This study indicates that it might be more efficient, for the health of the European population, to decrease primary PM emissions (especially in WEU) than to decrease precursors of SIA, but more knowledge on the toxicity of different PM constituents is needed before firm conclusions can be drawn. (C) 2009 Elsevier Ltd. All rights reserved.

  • 3. Borrego, C.
    et al.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Tchepel, O.
    Dias, D.
    Rafael, S.
    Sa, E.
    Pimentel, C.
    Fontes, T.
    Fernandes, P.
    Pereira, S. R.
    Bandeira, J. M.
    Coelho, M. C.
    Urban scale air quality modelling using detailed traffic emissions estimates2016In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 131, p. 341-351Article in journal (Refereed)
    Abstract [en]

    The atmospheric dispersion of NOx and PM10 was simulated with a second generation Gaussian model over a medium-size south-European city. Microscopic traffic models calibrated with GPS data were used to derive typical driving cycles for each road link, while instantaneous emissions were estimated applying a combined Vehicle Specific Power/Co-operative Programme for Monitoring and Evaluation of the Long-range Transmission of Air Pollutants in Europe (VSP/EMEP) methodology. Site-specific background concentrations were estimated using time series analysis and a low-pass filter applied to local observations. Air quality modelling results are compared against measurements at two locations for a 1 week period. 78% of the results are within a factor of two of the observations for 1-h average concentrations, increasing to 94% for daily averages. Correlation significantly improves when background is added, with an average of 0.89 for the 24 h record. The results highlight the potential of detailed traffic and instantaneous exhaust emissions estimates, together with filtered urban background, to provide accurate input data to Gaussian models applied at the urban scale. (C) 2016 Elsevier Ltd. All rights reserved.

  • 4. Carlsen, Hanne Krage
    et al.
    Back, Erik
    Eneroth, Kristina
    Gislason, Thorarinn
    Holm, Mathias
    Janson, Christer
    Jensen, Steen Solvang
    Johannessen, Ane
    Kaasik, Marko
    Modig, Lars
    Segersson, David
    SMHI, Research Department, Air quality.
    Sigsgaard, Torben
    Forsberg, Bertil
    Olsson, David
    Orru, Hans
    Indicators of residential traffic exposure: Modelled NOX, traffic proximity, and self-reported exposure in RHINE III2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 167, p. 416-425Article in journal (Refereed)
  • 5. Carmichael, G R
    et al.
    Calori, G
    Hayami, H
    Uno, I
    Cho, S Y
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Kim, S B
    Ichikawa, Y
    Ikeda, Y
    Woo, J H
    Ueda, H
    Amann, M
    The MICS-Asia study: model intercomparison of long-range transport and sulfur deposition in East Asia2002In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 36, no 2, p. 175-199Article in journal (Refereed)
    Abstract [en]

    An intercomparison study involving eight long-range transport models for sulfur deposition in East Asia has been initiated, The participating models included Eulerian and Lagrangian frameworks, with a wide variety of vertical resolutions and numerical approaches. Results from this study, in which models used common data sets for emissions, meteorology, and dry, wet and chemical conversion rates, are reported and discussed. Model results for sulfur dioxide and sulfate concentrations, wet deposition amounts, for the period January and May 1993, are compared with observed quantities at 18 surface sites in East Asia. At many sites the ensemble of models is found to have high skill in predicting observed quantities. At other sites all models show poor predictive capabilities. Source-receptor relationships estimated by the models are also compared. The models show a high degree of consistency in identifying the main source-receptor relationships, as well as in the relative contributions of wet/dry pathways for removal. But at some locations estimated deposition amounts can vary by a factor or 5. The influence of model structure and parameters on model performance is discussed. The main factors determining the deposition fields are the emissions and underlying meteorological fields. Model structure in terms of vertical resolution is found to be more important than the parameterizations used for chemical conversion and removal, as these processes are highly coupled and often work in compensating directions. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 6. Carmichael, G. R.
    et al.
    Sakurai, T.
    Streets, D.
    Hozumi, Y.
    Ueda, H.
    Park, S. U.
    Fung, C.
    Han, Z.
    Kajino, M.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Hayami, H.
    Sartelet, K.
    Holloway, T.
    Wang, Z.
    Kannari, A.
    Fu, J.
    Matsuda, K.
    Thongbooncho, N.
    Amann, M.
    MICS-Asia II: The model intercomparison study for Asia Phase II methodology and overview of findings2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 15, p. 3468-3490Article, review/survey (Refereed)
    Abstract [en]

    Results from the Model Intercomparison Study Asia Phase II (MICS-Asia II) are presented. Nine different regional modeling groups simulated chemistry and transport of ozone (O-3), secondary aerosol, acid deposition, and associated precursors, using common emissions and boundary conditions derived from a global model. Four-month-long periods, representing 2 years and three seasons (i.e., March, July, and December in 2001, and March in 2002), are analyzed. New observational data, obtained under the EANET (the Acid Deposition Monitoring Network in East Asia) monitoring program, were made available for this study, and these data provide a regional database to compare with model simulations. The analysis focused around seven subject areas: O-3 and related precursors, aerosols, acid deposition, global inflow of pollutants and precursor to Asia, model sensitivities to aerosol parameterization, analysis of emission fields, and detailed analyses of individual models, each of which is presented in a companion paper in this issue of Atmospheric Environment. This overview discusses the major findings of the study, as well as information on common emissions, meteorological conditions, and observations. (C) 2007 Elsevier Ltd. All rights reserved.

  • 7. Denby, B. R.
    et al.
    Sundvor, I.
    Johansson, C.
    Pirjola, L.
    Ketzel, M.
    Norman, M.
    Kupiainen, K.
    Gustafsson, M.
    Blomqvist, G.
    Kauhaniemi, M.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 2: Surface moisture and salt impact modelling2013In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 81, p. 485-503Article in journal (Refereed)
    Abstract [en]

    Non-exhaust traffic induced emissions are a major source of airborne particulate matter in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. Though the total mass generated by wear sources is a key factor in non-exhaust emissions, these emissions are also strongly controlled by surface moisture conditions. In this paper, Part 2, the road surface moisture submodel of a coupled road dust and surface moisture model (NORTRIP) is described. We present a description of the road surface moisture part of the model and apply the coupled model to seven sites in Stockholm, Oslo, Helsinki and Copenhagen over 18 separate periods, ranging from 3.5 to 24 months. At two sites surface moisture measurements are available and the moisture sub-model is compared directly to these observations. The model predicts the frequency of wet roads well at both sites, with an average fractional bias of -2.6%. The model is found to correctly predict the hourly surface state, wet or dry, 85% of the time. From the 18 periods modelled using the coupled model an average absolute fractional bias of 15% for PM10 concentrations was found. Similarly the model predicts the 90'th daily mean percentiles of PMio with an average absolute bias of 19% and an average correlation (R-2) of 0.49. When surface moisture is not included in the modelling then this average correlation is reduced to 0.16, demonstrating the importance of the surface moisture conditions. Tests have been carried out to assess the sensitivity of the model to model parameters and input data. The model provides a useful tool for air quality management and for improving our understanding of non-exhaust traffic emissions. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.

  • 8. Denby, B. R.
    et al.
    Sundvor, I.
    Johansson, C.
    Pirjola, L.
    Ketzel, M.
    Norman, M.
    Kupiainen, K.
    Gustafsson, M.
    Blomqvist, G.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    A coupled road dust and surface moisture model to predict non-exhaust road traffic induced particle emissions (NORTRIP). Part 1: Road dust loading and suspension modelling2013In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 77, p. 283-300Article in journal (Refereed)
    Abstract [en]

    Non-exhaust traffic induced emissions are a major source of particle mass in most European countries. This is particularly important in Nordic and Alpine countries where winter time road traction maintenance occurs, e.g. salting and sanding, and where studded tyres are used. In this paper, Part 1, the road dust sub-model of a coupled road dust and surface moisture model (NORTRIP) is described. The model provides a generalised process based formulation of the non-exhaust emissions, with emphasis on the contribution of road wear, suspension, surface dust loading and the effect of road surface moisture (retention of wear particles and suspended emissions). The model is intended for use as a tool for air quality managers to help study the impact of mitigation measures and policies. We present a description of the road dust sub-model and apply the model to two sites in Stockholm and Copenhagen where seven years of data with surface moisture measurements are available. For the site in Stockholm, where studded tyres are in use, the model predicts the PM10 concentrations very well with correlations (R-2) in the range of R-2 = 0.76-0.91 for daily mean PM10. The model also reproduces well the impact of a reduction in studded tyres at this site. For the site in Copenhagen the correlation is lower, in the range 0.44-0.51. The addition of salt is described in the model and at both sites this leads to improved correlations due to additional salt emissions. For future use of the model a number of model parameters, e.g. wear factors and suspension rates, still need to be refined. The effect of sanding on PM10 emissions is also presented but more information will be required before this can be confidently applied for management applications. (C) 2013 Elsevier Ltd. All rights reserved.

  • 9.
    Devasthale, Abhay
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Thomas, Manu Anna
    SMHI, Research Department, Air quality.
    An investigation of statistical link between inversion strength and carbon monoxide over Scandinavia in winter using AIRS data2012In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 56, p. 109-114Article in journal (Refereed)
    Abstract [en]

    Temperature inversions influence the local air quality at smaller scales and the pollution transport at larger spatio-temporal scales and are one of the most commonly observed meteorological phenomena over Scandinavia (54 degrees N-70 degrees N, 0-30 degrees E) during winter. Here, apart from presenting key statistics on temperature inversions, a large-scale co-variation of inversion strength and carbon monoxide (CO), an ideal pollution tracer, is further quantified at six vertical levels in the free troposphere during three distinct meteorological regimes that are identified based on inversion strength. Collocated temperature and CO profiles from Atmospheric Infrared Sounder (AIRS) are used for this purpose. Higher values of CO (up to 15%) are observed over Scandinavia during weakly stable regimes at all vertical levels studied, whereas lower CO values (up to 10%) are observed when inversions become stronger and elevated. The observed systematic co-variation between CO and inversion strength in three meteorological regimes is most likely explained by the efficacy of long-range transport to influence tropospheric composition over Scandinavia. We argue that this large-scale co-variation of temperature inversions and CO would be a robust metric to test coupling of large-scale meteorology and chemistry in transport models. (C) 2012 Elsevier Ltd. All rights reserved.

  • 10. Emberson, L. D.
    et al.
    Bueker, P.
    Ashmore, M. R.
    Mills, G.
    Jackson, L. S.
    Agrawal, M.
    Atikuzzaman, M. D.
    Cinderby, S.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Jamir, C.
    Kobayashi, K.
    Oanh, N. T. K.
    Quadir, Q. F.
    Wahid, A.
    A comparison of North American and Asian exposure-response data for ozone effects on crop yields2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 12, p. 1945-1953Article, review/survey (Refereed)
    Abstract [en]

    Modelling-based studies to assess the extent and magnitude of ozone (O-3) risk to agriculture in Asia suggest that yield losses of 5-20% for important crops may be common in areas experiencing elevated O-3 concentrations. These assessments have relied on European and North American dose-response relationships and hence assumed an equivalent Asian crop response to O-3 for local cultivars, pollutant conditions and climate. To test this assumption we collated comparable dose-response data derived from fumigation, filtration and EDU experiments conducted in Asia on wheat. rice and leguminous crop species. These data are pooled and compared with equivalent North American dose-response relationships. The Asian data show that at ambient O-3 concentrations found at the study sites (which vary between similar to 35-75 ppb 4-8 h growing season mean), yield losses for wheat, rice and legumes range between 5-48, 3-47 and 10-65%, respectively. The results indicate that Asian grown wheat and rice cultivars are more sensitive to O-3 than the North American dose-response relationships would suggest. For legumes the scatter in the data makes it difficult to reach any equivalent conclusion in relative sensitivities. As such, existing modelling-based risk assessments may have substantially underestimated the scale of the problem in Asia through use of North American derived dose-response relationships. (c) 2009 Elsevier Ltd. All rights reserved.

  • 11.
    Engardt, Magnuz
    et al.
    SMHI, Research Department, Air quality.
    Leong, C P
    Regional modelling of anthropogenic sulphur in Southeast Asia2001In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 35, no 34, p. 5935-5947Article in journal (Refereed)
    Abstract [en]

    A co-operative research project between the Malaysian Meteorological Service (MMS) and the Swedish Meteorological and Hydrological Institute (SMHI) focussing on the usage of an atmospheric transport and chemistry model, has just been initiated. Here, we describe the main features of the dispersion model and discuss a first set of calculations in light of available measurements of sulphuric species in Southeast Asia. According to our results, anthropogenic sulphur concentrations and depositions are particularly high near the large cities of the region, around a metal smelter in the southern Philippines, and in a region extending from northern Vietnam into southeastern China. These areas coincide with the high-emissions regions of Southeast Asia and we tentatively conclude that regional transport of acidifying species is not as far-reaching as in the mid-latitudes. From our calculations, and from supporting measurements we conclude that most of rural Southeast Asia is not yet severely affected by anthropogenic sulphur, but given the rapid rate of economical development in this region the situation may deteriorate quickly. Areas that are particularly at risk include the large cities, northern Vietnam, most of central Thailand, most of peninsular Malaysia, eastern Sumatra and parts of Java, all of which receive total-sulphur depositions in excess of 0.5 g S m(-2) yr(-1). Our model simulates sulphate in precipitation in accordance with measurements, but it has a tendency to overestimate atmospheric SO2. It remains to be investigated whether this is a problem in the model formulation or a result of unrepresentative sampling. An immediate continuation of this study should be performed with higher spatial resolution than the currently used 100 x 100 km(2). Other imperfections in this model study, which should be addressed in future work, include parameterised vertical transport in deep convective clouds, the influence of natural emissions (primarily from volcanoes) on the concentration and deposition of sulphuric species, and the year-to-year variability of the driving meteorological conditions. (C) 2001 Elsevier Science Ltd. All rights reserved.

  • 12.
    Engardt, Magnuz
    et al.
    SMHI, Research Department, Air quality.
    Siniarovina, U
    Khairul, N I
    Leong, C P
    Country to country transport of anthropogenic sulphur in Southeast Asia2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 28, p. 5137-5148Article in journal (Refereed)
    Abstract [en]

    The MATCH model-driven by archived meteorological data from the ECMWF-has been used to study the long-range transport of pollutants in Southeast Asia during the year 2000. We have specifically investigated the atmospheric export and import of anthropogenic sulphur between nine countries in Southeast Asia as well as the import to these countries from the boundaries of our model domain, from southern China, and from international shipping in the surrounding waters. Compared to the conditions at the mid-latitudes (Europe, North America and East Asia), we find less long-range transport in this part of the world. In all countries in the region (except those with very small area, i.e. Singapore and Brunei), did the major part of the domestic emissions (60-70%) fall down on the emitting country itself. The fraction of the countries own emissions contributing to the total, annually accumulated, national deposition varied from 10% for Laos-which is a country with small emissions neighbouring large emitters-to 80-90% in countries not surrounded by significant emitters (i.e. Thailand, Indonesia, Singapore and Brunei). Sensitivity tests were performed to explore the uncertainties in the model simulations and to investigate to what extent the current results could be used for source-receptor relationships in the future, when the magnitude and location of the emissions may be different. We found that the general feature-with relatively little long-range transport of sulphur-will not be altered, while the absolute magnitude of the deposition in areas downwind of large emitters could change considerably if certain model parameters, or the emission patterns are changed. This is particularly true in light of the seasonal variation of the deposition pathways. The atmospheric import of anthropogenic sulphur from specific countries can vary by an order of magnitude between different months. Incidentally, a decrease in import from one country during a certain period is often compensated by a roughly equal increase of the import from another country during the same time. (c) 2005 Elsevier Ltd. All rights reserved.

  • 13. Fauser, P.
    et al.
    Ketzel, M.
    Becker, T.
    Plejdrup, M. S.
    Brandt, J.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Skarman, T.
    Bartonova, A.
    Schwarze, P.
    Karvosenoja, N.
    Paunu, V. -V
    Kukkonen, J.
    Karppinen, A.
    Human exposure to carcinogens in ambient air in Denmark, Finland and Sweden2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 167, p. 283-297Article in journal (Refereed)
  • 14.
    Foltescu, Valentin
    et al.
    SMHI.
    Pryor, S C
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Sea salt generation, dispersion and removal on the regional scale2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 11, p. 2123-2133Article in journal (Refereed)
    Abstract [en]

    The MATCH (Multi-scale Atmospheric Transport and Chemistry) modelling system has been used as the modelling platform for regional-scale sea salt simulations. A new model version for sea salt aerosols has been constructed and assessed. This study presents the model concept and shows that the model is capable of simulating sea salt on a regional scale. The model agrees well with observations, particularly in terms of the sea salt mass concentrations at certain locations in Northern Europe. The observed wet fluxes are generally under-predicted due in part to systematic under-prediction of precipitation by the meteorological model used to drive MATCH. (c) 2005 Elsevier Ltd. All rights reserved.

  • 15. FRANZEN, LG
    et al.
    HJELMROOS, M
    Kållberg, Per
    SMHI, Research Department, Meteorology.
    BRORSTROMLUNDEN, E
    JUNTTO, S
    SAVOLAINEN, AL
    THE YELLOW-SNOW EPISODE OF NORTHERN FENNOSCANDIA, MARCH-1991 - A CASE-STUDY OF LONG-DISTANCE TRANSPORT OF SOIL, POLLEN AND STABLE ORGANIC-COMPOUNDS1994In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 28, no 22, p. 3587-3604Article in journal (Refereed)
    Abstract [en]

    The present paper describes a vast dustfall with snow in northern Fennoscandia, 10 March 1991. The area affected by dust deposition was at least 320,000 km(2). and the particulate mass received amounted to between 50 and 200 mg m(-2). The total amounts of dust deposited in the investigated area sum up to approximately 50,000 tonnes. The dust consisted of soil particles, i.e. single mineral grains and loose ferric aggregates of mineral grains in addition to pollen and spores. Mineralogically, the dust was dominated by small rounded quartz grains. Median size of the dust particles was 2.72 mu m. The total pollen concentration varied from 327 to 1172 pollen cm(-2). The pollen types identified were divided in ''Nordic/Central European'' taxa and ''Exotic'' taxa. Pollen from the former group, e.g. Betula, Alnus and Corylus were believed to originate in the Alps and in the northern parts of Central Europe where these species were flowering. The latter category was considered to originate in more remote areas, many of them belonging to the taxa growing only around the Mediterranean. From a paleo-ecological point of view, long-distance transport such as this would count for an important potential source of error whenever interpreting Holocene pollen diagrams. The content of stable organic compounds showed that the dust was relatively clean, compared to other episodes, when the dust deposited had originated in heavily polluted regions. The small amounts of chlorinated hydrocarbons, polychlorinated biphenyles (PCB), polyaromated hydrocarbons (PAH) and other hydrocarbons found, are believed to have been adsorbed by the particle surfaces during transportation. The results of the study, along with meteorological data, lead to the conclusion that the material originated in North Africa. Dust mobilization was reported in Tunisia as well as in Algeria. This means that the dust was transported at least 7000 km before deposition.

  • 16. Gallardo, L
    et al.
    Olivares, G
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Aarhus Andrae, Bodil
    SMHI, Core Services.
    Coastal lows and sulfur air pollution in Central Chile2002In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 36, no 23, p. 3829-3841Article in journal (Refereed)
    Abstract [en]

    Air pollutants in Santiago (33.5degreesS, 70.8degreesW, 500m a.s.l.), a city with 5 million inhabitants, located in a basin in Central Chile surrounded by the high Andes, frequently exceed air quality standards. This affects human health and it stresses vegetation. The most extreme winter and fall pollution events occur when the subsident regime of the Pacific high is further enhanced by coastal lows (CLs), which bring down the base of the subsidence inversion. Under these conditions, the air quality worsens significantly giving rise to acute air pollution episodes. We assess the ability of a regional transport/chemistry/deposition model (MATCH) coupled to a meteorological model (High Resolution Limited Area Model-HIRLAM) to simulate the evolution of oxidized sulfur (SOx) in connection with intensive CLs. We focus on SOx since it is an environmental issue of concern, and the emissions and concentrations of SOx have been regularly monitored making it easier to bracket model outputs for SOx than for other pollutants. Furthermore, the SOx emissions in the area are very large, i.e., about 0.4% of the global anthropogenic sources. Comparisons with observations indicate that the combination of HIRLAM and MATCH is a suitable tool for describing the regional patterns of dispersion associated with CLs. However, the low number and the limited geographical coverage of reliable air quality data preclude a complete evaluation of the model. Nevertheless, we show evidence of an enhanced contribution of the largest copper smelter in the area, i.e., Caletones, to the burden of SOx in the Santiago basin, especially in the form of sulfate associated to fine particles (diameters < 2.5 mum), during CLs. Further, we speculate that the Caletones plume may trigger or promote secondary aerosol formation during CLs in the Santiago basin. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 17. Galmarini, S
    et al.
    Bianconi, R
    Klug, W
    Mikkelsen, T
    Addis, R
    Andronopoulos, S
    Astrup, P
    Baklanov, A
    Bartniki, J
    Bartzis, J C
    Bellasio, R
    Bompay, F
    Buckley, R
    Bouzom, M
    Champion, H
    D'Amours, R
    Davakis, E
    Eleveld, H
    Geertsema, G T
    Glaab, H
    Kolax, Michael
    SMHI, Research Department, Climate research - Rossby Centre.
    Ilvonen, M
    Manning, A
    Pechinger, U
    Persson, Christer
    SMHI, Research Department, Air quality.
    Polreich, E
    Potemski, S
    Prodanova, M
    Saltbones, J
    Slaper, H
    Sofiev, M A
    Syrakov, D
    Sorensen, J H
    Van der Auwera, L
    Valkama, I
    Zelazny, R
    Ensemble dispersion forecasting - Part I: concept, approach and indicators2004In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 38, no 28, p. 4607-4617Article in journal (Refereed)
    Abstract [en]

    The paper presents an approach to the treatment and analysis of long-range transport and dispersion model forecasts. Long-range is intended here as the space scale of the order of few thousands of kilometers known also as continental scale. The method is called multi-model ensemble dispersion and is based on the simultaneous analysis of several model simulations by means of ad-hoc statistical treatments and parameters. The models considered in this study are operational long-range transport and dispersion models used to support decision making in various countries in case of accidental releases of harmful volatile substances, in particular radionuclides to the atmosphere. The ensemble dispersion approach and indicators provide a way to reduce several model results to few concise representations that include an estimate of the models' agreement in predicting a specific scenario. The parameters proposed are particularly suited for long-range transport and dispersion models although they can also be applied to short-range dispersion and weather fields. (C) 2004 Elsevier Ltd. All rights reserved.

  • 18. Galmarini, S.
    et al.
    Bonnardot, F.
    Jones, A.
    Potempski, S.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Martet, M.
    Multi-model vs. EPS-based ensemble atmospheric dispersion simulations: A quantitative assessment on the ETEX-1 tracer experiment case2010In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 44, no 29, p. 3558-3567Article in journal (Refereed)
    Abstract [en]

    Several techniques have been developed over the last decade for the ensemble treatment of atmospheric dispersion model predictions. Among them two have received most of the attention, the multi-model and the ensemble prediction system (EPS) modeling. The multi-model approach relies on model simulations produced by different atmospheric dispersion models using meteorological data from potentially different weather prediction systems. The EPS-based ensemble is generated by running a single atmospheric dispersion model with the ensemble weather prediction members. In the paper we compare both approaches with the help of statistical indicators, using the simulations performed for the ETEX-1 tracer experiment. Both ensembles are also evaluated against measurement data. Among the most relevant results is that the multi-model median and the mean of EPS-based ensemble produced the best results, hence we consider a combination of multi-model and EPS-based approaches as an interesting suggestion for further research. (C) 2010 Elsevier Ltd. All rights reserved.

  • 19.
    Gidhagen, Lars
    et al.
    SMHI, Research Department, Air quality.
    Johansson, C
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Foltescu, Valter
    SMHI.
    Urban scale modeling of particle number concentration in Stockholm2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 9, p. 1711-1725Article in journal (Refereed)
    Abstract [en]

    A three-dimensional dispersion model has been implemented over the urban area of Stockholm (35 x 35 km) to assess the spatial distribution of number concentrations of particles in the diameter range 3-400 nm. Typical number concentrations in the urban background of Stockholm is 10 000 cm(-3), while they are three times higher close to a major highway outside the city and seven times higher within a densely trafficked street canyon site in the city center. The model, which includes an aerosol module for calculating the particle number losses due to coagulation and dry deposition, has been run for a 10-day period. Model results compare well with measured data, both in levels and in temporal variability. Coagulation was found to be of little importance in terms of time averaged concentrations, contributing to losses of only a few percent as compared to inert particles, while dry deposition yield particle number losses of up to 25% in certain locations. Episodic losses of up to 10% due to coagulation and 50% due to deposition, are found some kilometers downwind of major roads, rising in connection with low wind speed and suppressed turbulent mixing. Removal due to coagulation and deposition will thus be more significant for the simulation of extreme particle number concentrations during peak episodes. The study shows that dispersion models with proper aerosol dynamics included may be used to assess particle number concentrations in Stockholm, where ultrafine particles principally originate from traffic emissions. Emission factors may be determined from roadside measurements, but ambient temperature must be considered, as it has a strong influence on particle number emissions from vehicles. (c) 2005 Elsevier Ltd. All rights reserved.

  • 20.
    Gidhagen, Lars
    et al.
    SMHI, Research Department, Air quality.
    Johansson, C
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Olivares, G
    Simulation of NOx and ultrafine particles in a street canyon in Stockholm, Sweden2004In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 38, no 14, p. 2029-2044Article in journal (Refereed)
    Abstract [en]

    A computational fluid dynamic (CFD) model has been used to assess the concentrations of NO, and particle number in a street canyon in Stockholm with a high traffic volume. Comparisons of a simulated 11-week long time series of NOx with measurements (both sides of the street, urban background excluded) show good agreement, especially if emissions are distributed to be three times higher along the side of the street where the traffic is uphill, as compared to the downhill side. The simulation of number concentrations of inert particles indicates a similar asymmetry in emissions. A month-long measurement of particle size distribution (7-450 nm) at street level indicates that the ratio of nucleation size mode particle (7-20 nm) to total particle number (7-450 nm) is decreasing for increased particle surface area. Given the strong dominance of the locally generated particles over the urban background, this is interpreted as a local change in the size distribution. The results of a monodisperse aerosol dynamic model, coupled to the CFD model that simulates also the turbulence generated by vehicle movements, show that coagulation and deposition may reduce total particle inside the canyon with approximately 30% during low wind speeds. Most of the removal occurs shortly after emission, before the particles reach the leeward curb-side. Losses between the leeward curb-side and other locations in the street, e.g. roof levels, is estimated to be smaller, less than 10%. Coagulation is the dominating removal process under low wind speed conditions and deposition for higher wind speeds, the summed removal being smaller for high wind velocities. Deposition is enhanced over the road surface due to the velocities generated by vehicle movements. Although coagulation and deposition removal is most effective on the smallest ultrafine particles, this effect is not sufficient to explain the observed change in size distribution. It is suggested that also the formation of particles in the exhaust plumes is influenced by a larger particle surface area in the ambient air. (C) 2004 Elsevier Ltd. All rights reserved.

  • 21.
    Gidhagen, Lars
    et al.
    SMHI, Research Department, Air quality.
    Johansson, C
    Strom, J
    Kristensson, A
    Swietlicki, E
    Pirjola, L
    Hansson, H C
    Model simulation of ultrafine particles inside a road tunnel2003In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 37, no 15, p. 2023-2036Article in journal (Refereed)
    Abstract [en]

    A monodispersive aerosol dynamic model, coupled to a 3D hydrodynamical grid model, has been used to study the dynamics of ultrafine particles inside a road tunnel in Stockholm, Sweden. The model results were compared to measured data of particle number concentrations, traffic intensity and tunnel ventilation rate. Coagulation and depositional losses to the tunnel walls were shown to be important processes during traffic peak hours, together contributing to losses of 77% of the particles smaller than 10nm and 41% of the particles of size 10-29nm. Particle growth due to water uptake or the presence of a micron-sized, resuspended particle fraction did not have any significant effect on the number of particles lost due to coagulation. Model simulation of particle number concentration response to temporal variations in traffic flow showed that constant emission factors could be used to reproduce the concentration variations of the particles larger than 29nm, while vehicle-speed-dependent factors are suggested to reproduce the variation of the smallest fractions. The emission factors for particle number concentrations estimated from the model simulation are in general higher and show a larger contribution from light-duty vehicles than what has been reported from a tunnel in California. The model study shows that combined measurements and model simulations in road tunnels can be used to improve the determinations of vehicle emission factors for ultrafine particles under realistic driving conditions. (C) 2003 Elsevier Science Ltd. All rights reserved.

  • 22.
    Gidhagen, Lars
    et al.
    SMHI, Research Department, Air quality.
    Johansson, H.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    SIMAIR-Evaluation tool for meeting the EU directive on air pollution limits2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 5, p. 1029-1036Article in journal (Refereed)
    Abstract [en]

    Almost all Swedish cities need to determine air pollution levels especially PM10-close to major streets. SIMAIR is an internet tool that can be used by all Swedish municipalities to assess PM10, NO(2), CO and benzene levels and how they compare to the EU directive. SIMAIR is delivered to the municipalities with all required input data pre-loaded and is meant to be used prior to decisions if and where, monitoring campaigns are required. The system includes a road and vehicle database with emission factors and a model to calculate non tailpipe PM10 emissions. Regional and urban background contributions are pre-calculated and stored as hourly values oil a 1 x 1 km(2) grid. The local contribution is calculated by the user, selecting either an open road or a street canyon environment. A comparison between measured and simulated concentrations in four street locations shows that SIMAIR is able to Calculate statistics of yearly mean values, 90-percentile and 98-percentile daily mean values and the number of days exceeding the limit value that are well within +/- 50% that EU requires for model estimates of yearly mean values. In comparison, all Values except one are within +/- 25% which is the quality objective for fixed measurements according to the EU directive. The SIMAIR model system is also able to separate the percentual contribution of the long-range transport from Outside the city, the city contribution and the local contribution from the traffic of an individual street. (C) 2008 Elsevier Ltd. All rights reserved.

  • 23.
    Gidhagen, Lars
    et al.
    SMHI, Research Department, Air quality.
    Kahelin, H
    Schmidt-Thome, P
    Johansson, C
    Anthropogenic and natural levels of arsenic in PM10 in Central and Northern Chile2002In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 36, no 23, p. 3803-3817Article in journal (Refereed)
    Abstract [en]

    A few copper and gold smelters in Chile are behind a large fraction of global arsenic emissions, raising concerns for increased concentrations of arsenic in PM10 in Central and Northern Chile. This concern is amplified by the fact that Northern Chile soils and rivers in general are characterized by a high arsenic content. A monitoring and modeling study has been performed to quantify the regional impact of the smelter emissions. Measured atmospheric arsenic concentrations from 2.4 to 30.7 ng m(-3) were found at seven rural stations, located tens to hundreds of kilometers away from the nearest smelter. Analyses of topsoil and subsoil samples taken from PM 10 monitoring stations revealed levels up to 291 mg kg(-1), the highest values found in the northern Atacama desert in Chile. An absolute principal component analysis of selected trace elements in PM10 shows that the regional impact of anthropogenic smelter emissions on airborne arsenic concentrations is more important than the effect of soil dust resuspension. The dominance of the smelter emissions is larger in Central Chile than in the northern parts. The impact of resuspended soil dust on airborne arsenic levels in rural areas was estimated not to exceed 5 ng m(-3). The model calculations support the dominant role of anthropogenic emissions and give spatial and temporal variations in atmospheric concentrations consistent with the monitored levels at five of the seven stations. At two of the northernmost stations indications were found of unidentified sources other than the smelters and the resuspended soil dust, contributing to about 5 ng m(-3) of total arsenic levels. The study confirms that a strong control or elimination of arsenic emissions from the smelters would lead to arsenic in PM10 levels in Northern and Central Chile comparable to non-polluted areas in other countries. (C) 2002 Elsevier Science Ltd. All rights reserved.

  • 24. Gramsch, Ernesto
    et al.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Wahlin, Peter
    Oyola, Pedro
    Moreno, Francisco
    Predominance of soot-mode ultrafine particles in Santiago de Chile: Possible sources2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 14, p. 2260-2267Article in journal (Refereed)
    Abstract [en]

    A monitoring campaign was performed in Santiago de Chile during a winter month of 2003 and 2006 (July) using several instruments to measure the size distribution of particulate material. For the first time, the size distribution of ultrafine particles was measured in Santiago, and an estimation of its sources was done by analyzing its temporal variation. The study was performed in three sites: one of them is located in the eastern part of Santiago, a sector with low particle concentration and about 100 m from a busy street. The other site is located in the western part, which is the sector that has the highest concentration of fine and coarse particle matter during winter, also located far from a street. The third site is located within 5 in from the busiest street in Santiago. In all stations traffic is the dominating source for fine and ultrafine particles and the size distribution is peaked towards 60-100 nm (soot mode). Only in the site near the street, it is possible to see a clear peak towards smaller sizes (10-30 nm). The size distribution measurements presented here indicate that aerosol dynamics play a more important role for the Santiago case as compared to cleaner cities in Europe. Changes in the particle size during different hours of the day reflect both variations in meteorological mixing conditions as well as effects of aerosol dynamic processes such as coagulation, condensation and dry deposition. A relative increase in the number of the larger ultrafine particles (d >= 70 nm), as compared to the number of smaller particles (d < 70 nm) correlated with wind speed is an indication of pollution transport with aged particles from other parts of the city. (C) 2009 Elsevier Ltd. All rights reserved.

  • 25. Han, Z.
    et al.
    Sakurai, T.
    Ueda, H.
    Carmichael, G. R.
    Streets, D.
    Hayami, H.
    Wang, Z.
    Holloway, T.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Hozumi, Y.
    Park, S. U.
    Kajino, M.
    Sartelet, K.
    Fung, C.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Thongboonchoo, N.
    Tang, Y.
    Chang, A.
    Matsuda, K.
    Amann, M.
    MICS-Asia II: Model intercomparison and evaluation of ozone and relevant species2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 15, p. 3491-3509Article in journal (Refereed)
    Abstract [en]

    Eight regional Eulerian chemical transport models (CTMs) are compared with each other and with an extensive set of observations including ground-level concentrations from EANET, ozone soundings from JMA and vertical profiles from the TRACE-P experiment to evaluate the models' abilities in simulating O(3) and relevant species (SO(2), NO, NO(2), HNO(3) and PAN) in the troposphere of East Asia and to look for similarities and differences among model performances. Statistical analysis is conducted to help estimate the consistency and discrepancy between model simulation and observation in terms of various species, seasons, locations, as well as attitude ranges. In general, all models show a good skill of simulating SO(2) for both ground level and the lower troposphere, although two of the eight models systematically overpredict SO(2) concentration. The model skills for O(3) vary largely with region and season. For ground-level O(3), model results are best correlated with observations in July 2001. Comparing with O(3) soundings measured in the afternoon reveals the best consistency among models in March 2001 and the largest disparity in O(3) magnitude in July 2001, although most models produce the best correlation in July as well. In terms of the statistics for the four flights of TRACE-P experiment, most models appear to be able to accurately capture the variability in the lower troposphere. The model performances for NO(x) are relatively poor, with lower correlation and with almost all models tending to underpredict NO(x) levels, due to larger uncertainties in either emission estimates or complex chemical mechanism represented. All models exhibit larger RMSE at altitudes < 2 km than 2-5.5 kin, mainly due to a consistent tendency of these models towards underprediction of the magnitude of intense plumes that often originate from near surface. Relatively lower correlation at altitudes 2-5.5 km may be attributed to the models' limitation in representing convection or potential chemical processes. Most of the key features in species distribution have been consistently reproduced by the participating models, such as the O(3) enhancement in the western Pacific Ocean in March and in northeast Asia in July, respectively, although the absolute model values may differ considerably from each other. Large differences are found among models in the southern parts of the domain for all the four periods, including southern China and northern parts of some Southeast Asia countries where the behaviors of chemical components and the ability of these models are still not clearly known because of a lack of observational databases. (C) 2007 Elsevier Ltd. All rights reserved.

  • 26. Hayami, Hiroshi
    et al.
    Sakurai, T.
    Han, Z.
    Ueda, H.
    Carmichael, G. R.
    Streets, D.
    Holloway, T.
    Wang, Z.
    Thongboonchoo, N.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Fung, C.
    Chang, A.
    Park, S. U.
    Kajino, M.
    Sartelet, K.
    Matsuda, K.
    Amann, M.
    MICS-Asia II: Model intercomparison and evaluation of particulate sulfate, nitrate and ammonium2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 15, p. 3510-3527Article in journal (Refereed)
    Abstract [en]

    Eight chemical transport models participate in a model intercomparison study for East Asia, MICS-Asia II. This paper analyzes calculated results for particulate matter of sulfate, nitrate and ammonium through comparisons with each other and with monthly measurements at EANET (the acid deposition monitoring network in East Asia) and daily measurements at Fukue, Japan. To the EANET measurements, model ensemble means better agree with model individual results for sulfate and total ammonium, although total nitrate is consistently and considerably underestimated. To measurements at Fukue, the models show better agreement than for the EANET measurements. This is likely because Fukue is centered in many of the model domains, whereas the EANET stations are mostly in Southeast Asia and Russia. Moreover, it would be important that Fukue is in Northeast Asia, where the emission inventory is more reliable than Southeast Asia. The model-model comparisons are made in view of the total amount in the atmosphere, vertical profile, coefficient of variation in surface concentrations, and transformation changes with distance. All the models show reasonable tendencies in vertical profiles and composition ratios. However, total amounts in the atmosphere are discrepant among the models. The consistency of the total amount in the atmosphere would influence source-receptor analysis. It seems that model results would be consistent, if the models take into account the primitive processes like emission, advection/diffusion, chemical transformation and dry/wet deposition, no matter the processes are modeled simply or comprehensively. Through the comparison study, we learned that it would be difficult to find any problems from one comparison (model-observation comparison with one data or many but at one station or in a short period). Modelers tend to examine model performances only from model-observation comparisons. However, taking budget in a certain or whole model domain would be important, before the models are applied to source-receptor analysis. (C) 2007 Elsevier Ltd. All rights reserved.

  • 27. Hedberg, E
    et al.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Johansson, C
    Source contributions to PM10 and arsenic concentrations in Central Chile using positive matrix factorization2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 3, p. 549-561Article in journal (Refereed)
    Abstract [en]

    Sampling of particles (PM10) was conducted during a one-year period at two rural sites in Central Chile, Quillota and Linares. The samples were analyzed for elemental composition. The data sets have undergone source-recepior analyses in order to estimate the sources and their abundance's in the PM10 size fraction. by using the factor analytical method positive matrix factorization (PMF). The analysis showed that PM10 was dominated by soil resuspension at both sites during the summer months, while during winter traffic dominated the particle mass at Quillota and local wood burning dominated the particle mass at Linares. Two copper smelters impacted the Quillota station, and contributed to 10% and 16% of PM10 as an average during summer and winter. respectively. One smelter impacted Linares by 8% and 19% of PM10 in the summer and winter, respectively. For arsenic the two smelters accounted for 87% of the monitored arsenic levels at Quillota and at Linares one smelter contributed with 72% of the measured mass. In comparison with PMF, the use of a dispersion model tended to overestimate the smelter contribution to arsenic levels at both sites. The robustness of the PMF model was tested by using randomly reduced data sets, where 85%, 70%, 50% and 33% of the samples were included. In this way the ability of the model to reconstruct the sources initially found by the original data set could be tested. On average for all sources the relative standard deviation increased from 7% to 25% for the variables identifying the sources, when decreasing the data set from 85% to 33% of the samples, indicating that the solution initially found was very stable to begin with. But it was also noted that sources due to industrial or combustion processes were more sensitive for the size of the data set, compared to the natural sources as local soil and sea spray sources. (C) 2004 Elsevier Ltd. All rights reserved.

  • 28. Holloway, Tracey
    et al.
    Sakurai, Tatsuya
    Han, Zhiwei
    Ehlers, Susanna
    Spak, Scott N.
    Horowitz, Larry W.
    Carmichael, Gregory R.
    Streets, David G.
    Hozumi, Y.
    Ueda, Hiromasa
    Park, S. U.
    Fung, Christopher
    Kajino, M.
    Thongboonchoo, Narisara
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Hayami, Hiroshi
    Sartelet, Karine
    Wang, Zifa
    Matsuda, K.
    Amann, Markus
    MICS-Asia II: Impact of global emissions on regional air quality in Asia2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 15, p. 3543-3561Article in journal (Refereed)
    Abstract [en]

    This study quantifies the seasonality and geographic variability of global pollutant inflow to Asia. Asia is often looked to as a major source of intercontinental air pollution transport with rising emissions and efficient pollutant export processes. However, the degree to which foreign emissions have been imported to Asia has not been thoroughly examined. The Model Inter-Comparison Study for Asia (MICS-Asia) is an international collaboration to study air pollution transport and chemistry in Asia. Using the global atmospheric chemistry Model of Ozone and Related Tracers (MOZART v. 2.4), and comparing results with a suite of regional models participating in MICS-Asia, we find that imported O-3 contributes significantly throughout Asia. The choice of upper boundary condition is found to be particularly important for O-3, even for surface concentrations. Both North America and Europe contribute to ground-level O-3 concentrations throughout the region, though the seasonality of these two sources varies. North American contributions peak at over 10% of monthly mean O-3 during winter months in East Asia, compared to Europe's spring- and autumn-maxima (5-8%). In comparison to observed data from the Acid Deposition Monitoring Network in East Asia (EANET), MOZART concentrations for 03 generally fall within the range of the MICS models, but MOZART is unable to capture the fine spatial variability of shorter-lived species as well as the regional models. (C) 2007 Elsevier Ltd. All rights reserved.

  • 29. Jonsson, P
    et al.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Eliasson, I
    Lindgren, E S
    Suspended particulate matter and its relations to the urban climate in Dar es Salaam, Tanzania2004In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 38, no 25, p. 4175-4181Article in journal (Refereed)
    Abstract [en]

    Relationships between sources and levels of particulate matter and climatic parameters (urban heat island intensity, wind speed, temperature and relative humidity) were investigated in the coastal city of Dar es Salaam, Tanzania's largest city. Measurements were made during the wet and dry seasons of 2001 at an urban and a rural site. Five elements were used to represent different sources: K in fine particles (biomass), Zn in fine particles (industry), Cl in coarse particles (sea spray), Ti in coarse particles (soil) and Pb in fine particles (traffic). The concentrations of these elements varied considerably between the urban and rural site during both the wet and dry season, with the urban site in the dry season having the highest concentrations. Diurnal differences are also apparent, although not as straightforward. In an attempt to explain these differences, correlations between all elements and the climatic parameters were investigated. The results show that the nocturnal urban heat island intensity was positively correlated and wind speed negatively correlated with particulate levels, presumably due to the increased atmospheric stability. (C) 2004 Elsevier Ltd. All rights reserved.

  • 30. Kauhaniemi, M.
    et al.
    Kukkonen, J.
    Harkonen, J.
    Nikmo, J.
    Kangas, L.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Ketzel, M.
    Kousa, A.
    Haakana, M.
    Karppinen, A.
    Evaluation of a road dust suspension model for predicting the concentrations of PM10 in a street canyon2011In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 45, no 22, p. 3646-3654Article in journal (Refereed)
    Abstract [en]

    We have slightly refined, evaluated and tested a mathematical model for predicting the vehicular suspension emissions of PM10. The model describes particulate matter generated by the wear of road pavement, traction sand, and the processes that control the suspension of road dust particles into the air. However, the model does not address the emissions from the wear of vehicle components. The performance of this suspension emission model has been evaluated in combination with the street canyon dispersion model OSPM. We used data from a measurement campaign that was conducted in the street canyon Runeberg Street in Helsinki from 8 January to 2 May, 2004. The model reproduced fairly well the seasonal variation of the PM10 concentrations, also during the time periods, when studded tyres and anti-skid treatments were commonly in use. For instance, the index of agreement (IA) was 0.83 for the time series of the hourly predicted and observed concentrations of PM10. The predictions of the model were found to be sensitive to precipitation and street traction sanding. The main uncertainties in the predictions are probably caused by (i) the cleaning processes of the streets, which are currently not included in the model, (ii) the uncertainties in the estimation of the sanding days, and (iii) the uncertainties in the evaluation of precipitation. This study provides more confidence that this model could potentially be a valuable tool of assessment to evaluate and forecast the suspension PM10 emissions worldwide. However, a further evaluation of the model is needed against other datasets in various vehicle fleet, speed and climatic conditions. (C) 2011 Elsevier Ltd. All rights reserved.

  • 31. Ketzel, Matthias
    et al.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Johansson, Christer
    Duering, Ingo
    Pohjolar, Mia
    Oettl, Dietmar
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Wahlin, Peter
    Lohmeyer, Achim
    Haakana, Mervi
    Berkowicz, Ruwim
    Estimation and validation of PM2.5/PM10 exhaust and non-exhaust emission factors for practical street pollution modelling2007In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 41, no 40, p. 9370-9385Article in journal (Refereed)
    Abstract [en]

    In order to carry out efficient traffic and air quality management, validated models and PM emission estimates are needed. This paper compares current available emission factor estimates for PM10 and PM2.5 from emission databases and different emission models, and validates these against eight high quality street pollution measurements in Denmark, Sweden, Germany, Finland and Austria. The data sets show large variation of the PM concentration and emission factors with season and with location. Consistently at all roads the PM10 and PM2.5 emission factors are lower in the summer month than the rest of the year. For example, PM10 emission factors are in average 5-45% lower during the month 6-10 compared to the annual average. The range of observed total emission factors (including non-exhaust emissions) for the different sites during summer conditions are 80-130mgkm(-1) for PM10, 30-60mgkm(-1) for PM2.5 and 20-50mgkm(-1) for the exhaust emissions. We present two different strategies regarding modelling of PM emissions: (1) For Nordic conditions with strong seasonal variations due to studded tyres and the use of sand/salt as anti-skid treatment a time varying emission model is needed. An empirical model accounting for these Nordic conditions was previously developed in Sweden. (2) For other roads with a less pronounced seasonal variation (e.g. in Denmark, Germany, Austria) methods using a constant emission factor maybe appropriate. Two models are presented here. Further, we apply the different emission models to data sets outside the original countries. For example, we apply the "Swedish" model for two streets without studded tyre usage and the "German", model for Nordic data sets. The "Swedish" empirical model performs best for streets with studded tyre use, but was not able to improve the correlation versus measurements in comparison to using constant emission factors for the Danish side. The "German" method performed well for the streets without clear seasonal variation and reproduces the summer conditions for streets with pronounced seasonal variation. However, the seasonal variation of PM emission factors can be important even for countries not using studded tyres, e.g. in areas with cold weather and snow events using sand and de-icing materials. Here a constant emission factor probably will under-estimate the 90-percentiles and therefore a time varying emission model need to be used or developed for such areas. All emission factor models consistently indicate that a large part (about 50-85% depending on the location) of the total PM10 emissions originates from non-exhaust emissions. This implies that reduction measures for the exhaust part of the vehicle emissions will only have a limited effect on ambient PM10 levels. (C) 2007 Elsevier Ltd. All rights reserved.

  • 32. Kristensson, A
    et al.
    Johansson, C
    Westerholm, R
    Swietlicki, E
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Wideqvist, U
    Vesely, V
    Real-world traffic emission factors of gases and particles measured in a road tunnel in Stockholm, Sweden2004In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 38, no 5, p. 657-673Article in journal (Refereed)
    Abstract [en]

    Measurements in a road tunnel in Stockholm, Sweden give the real-world traffic emission factors for a number of gaseous and particle pollutants. These include 49 different polycyclic aromatic hydrocarbons (PAH), CO, NOX, benzene, toluene, xylenes, aldehydes, elements and inorganic/organic carbon contained in particles, the sub-micrometer aerosol number size distribution, PM2.5 and PM10. The exhaust pipe emission factors are divided with the help of automated traffic counts into the two pollutant sources, the heavy-duty vehicles (HDV) and light-duty vehicles (LDV). The LDV fleet contains 95% petrol cars and the total fleet contains about 5% HDV. When data permitted, the emission factors were further calculated at different vehicle speeds. The current work shows that average CO, NOX and benzene emission factors amounted to 5.3, 1.4 and 0.017 g veh(-1) km(-1), respectively. Since the mid-90s CO and benzene decreased by about 15%, carbonyls by about a factor 2, whereas NOX did not change much. PAR emission factors were 2-15 times higher than found during dynamometer tests. Most particles are distributed around 20 nm diameter and the LDV fleet contributes to about 65% of both PM and particle number. In general, the gaseous emissions are higher in Sweden than in USA and Switzerland, foremost due to the lower fraction catalytic converters in Sweden. The PM and number emissions of particles are also slightly higher in the Swedish tunnel. (C) 2003 Elsevier Ltd. All rights reserved.

  • 33. Kulshrestha, U C
    et al.
    Granat, L
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Rodhe, H
    Review of precipitation monitoring studies in India - a search for regional patterns2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 38, p. 7403-7419Article, review/survey (Refereed)
    Abstract [en]

    This study is a review of rain chemistry measurements reported in India. Data from nearly 100 stations were reviewed with regard to sampling location, sampling method and chemical analyses. Some characteristic differences were found between the concentrations in different environments in line with known distributions of emissions. This was most clearly seen for with median concentration increasing from rural and suburban to urban and industrial environments, with concentrations of HCO3- and H+ varying the opposite way. Ca2+ concentration was higher in suburban and industrial environments compared to rural and urban. Concentration of NH4+ was lower in rural than in the other locations. Sea salt const, concentration (Na+ and Cl- in approximately 'Jut proport ion) was higher in urban than in rural locations at the same distance from the sea. The reported data from rural and Suburban locations were used to derive large-scale concentration fields over India. With knowledge of emission fields and with the aid of output from a regional transport model it was possible to see some limited spatial resemblance between modelled and observed concentrations in cases of SO2, NH4+, NO3- and SO42-. For soil dust, Current models are very crude but here some resemblance Could be seen: primarily limited spatial resemblance with Ca2+, pH and HCO3- with generally increasing values towards NW. Four sites, at least two of them located in forested environments, had a mean rainwater pH close to neutral (concentration or H+ and HCO3- about equal). Other sites had oil average an excess of HCO3-, becoming very substantial in the direction of the Thar Desert in NW India. With this review we conclude that there is a need to better assure the quality of the data with regard to sampling methods, chemical analyses and spatial representativeness. (c) 2005 Elsevier Ltd. All rights reserved.

  • 34. Lacressonniere, Gwendoline
    et al.
    Watson, Laura
    Gauss, Michael
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Beekmann, Matthias
    Colette, Augustin
    Foret, Gilles
    Josse, Beatrice
    Marecal, Virginie
    Nyiri, Agnes
    Siour, Guillaume
    Sobolowski, Stefan
    Vautard, Robert
    Particulate matter air pollution in Europe in a+2 degrees C warming world2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 154, p. 129-140Article in journal (Refereed)
  • 35.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Foltescu, Valentin
    SMHI.
    Impact of climate change on surface ozone and deposition of sulphur and nitrogen in Europe2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 6, p. 1129-1141Article in journal (Refereed)
    Abstract [en]

    The potential impact of regional climate change on the distribution and deposition of air pollutants in Europe has been studied using a regional chemistry/transport/deposition model, MATCH. MATCH was set up using meteorological output from two 10-year climate change experiments made with the Rossby Centre regional Atmospheric climate model version 1 (RCA1). RCA1 was forced by boundary conditions from two different global climate models using the IPCC IS92a (business as usual) emission scenario. The global mean warming in both the GCMs was 2.6 K and was reached in the period 2050-2070. Simulations with MATCH indicate substantial potential impact of regional climate change on both deposition of oxidised nitrogen and concentrations of surface ozone. The simulations show a strong increase in surface ozone expressed as AOT40 and mean of daily maximum over southern and central Europe and a decrease in northern Europe. The simulated changes in April September AOT40 are significant in relation to inter-annual variability over extended areas. Changes in deposition of oxidised nitrogen are much smaller and also less coherent due to the strong inter-annual variability in precipitation in the RCA1 simulations and differences in the regional climate change simulated with RCA1 in the two regional scenarios. Changes in simulated annual deposition are significant in relation to inter-annual variability only over small areas. This indicates that longer simulation periods are necessary to establish changes in deposition. (C) 2004 Elsevier Ltd. All rights reserved.

  • 36.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Validation of the operational emergency response model at the Swedish Meteorological and Hydrological Institute using data from ETEX and the Chernobyl accident1998In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 32, no 24, p. 4325-4333Article in journal (Refereed)
    Abstract [en]

    The Eulerian atmospheric tracer transport model MATCH (Multiscale Atmospheric Transport and Chemistry model) has been extended with a Lagrangian particle model treating the initial dispersion of pollutants from point sources. The model has been implemented at the Swedish Meteorological and Hydrological Institute in an emergency response system for nuclear accidents and can be activated on short notice to provide forecast concentration and deposition fields. The model has been used to simulate the transport of the inert tracer released during the ETEX experiment and the transport and deposition of Cs-137 from the Chernobyl accident. Visual inspection of the results as well as statistical analysis shows that the extent, time of arrival and duration of the tracer cloud, is in good agreement with the observations for both cases, with a tendency towards over-prediction for the first ETEX release. For the Chernobyl case the simulated deposition pattern over Scandinavia and over Europe as a whole agrees with observations when observed precipitation is used in the simulation. When model calculated precipitation is used, the quality of the simulation is reduced significantly and the model fails to predict major features of the observed deposition held. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • 37. Miao, J F
    et al.
    Chen, D
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling subgrid scale dry deposition velocity of O-3 over the Swedish west coast with MM5-PX model2006In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 40, no 3, p. 415-429Article in journal (Refereed)
    Abstract [en]

    A mesoscale meteorological model (MM5) coupled with an advanced land surface model (PX LSM) is used in this study to model high-resolution (2 km) dry deposition velocity of ozone over the Swedish west coast, together with a newly revised dry deposition parameterization for air-quality models with emphasis on non-stomatal resistance. The important air-surface exchange processes for air quality (surface fluxes of heat, moisture and momentum) are also simulated by this model. The modelled subgrid scale variability of the dry deposition velocity and its dependence on land use, terrain height and synoptic conditions are investigated. It is found that a systematic difference in the deposition velocity modelled by different resolutions exists, and the difference varies diurnally and daily. The subgrid scale variation is significant, which has a clear impact on the area-averaged deposition velocity. The deposition velocity depends strongly on land use and weather conditions, but not on topography for the area studied. Meteorological conditions at subgrid scales play an important role in determining the deposition velocity. It is also concluded that the dry deposition velocity simulated in this study is reasonable, and that a 6-km resolution would be practically good enough to resolve the inhomogeneity of the surface properties for dry deposition studies in this area. The variation range of dry deposition velocity over different land use categories and the corresponding resistances are outlined. Moreover, the difference in the estimated dry deposition velocitiy between the methods using fractional land use and using dominant land use is compared. (c) 2005 Elsevier Ltd. All rights reserved.

  • 38. Olivares, G
    et al.
    Gallardo, L
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Aarhus Andrae, Bodil
    SMHI, Core Services.
    Regional dispersion of oxidized sulfur in Central Chile2002In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 36, no 23, p. 3819-3828Article in journal (Refereed)
    Abstract [en]

    Chile has a long tradition of exploiting mineral resources, particularly copper (Cu). One of the largest Cu smelters, Caletones, located some 150 km south of the country's capital, Santiago, in Central Chile, is responsible for about 0.4% of about 70 Tg S/yr oxidized sulfur (SOx) emitted by anthropogenic sources worldwide. Santiago, a megacity with 5 million inhabitants, stands for about 5 Gg S/yr. The average meteorological conditions are unfavorable for the dispersion of pollutants in this area. All this poses risks for human health and vegetation. Also, downwind. from these polluted areas there may be large-scale impacts on cloud properties and on oxidative cycles. Here, we present the first attempt to assess the regional distribution of SOx in Central Chile using a dispersion model (MATCH) driven with data from a limited area weather forecast model (HIRLAM). Emphasis has been given to the impact of Cu smelters upon urban air quality, particularly that of Santiago. Six 1-month long periods were simulated for the years 1997, 1998 and 1999. These periods span over a broad range of typical meteorological conditions in the area including El Nino and La Nina years. Estimates of the regional dispersion and deposition patterns were calculated. The emissions from the large Cu smelters dominate the distribution of SOx. A budget of SOx over an area of 200 x 200 km 2 around Santiago is presented. There is too low a number of monitoring stations to perform a detailed evaluation of MATCH. Nevertheless, the model reproduces consistently all the regional-scale characteristics that can be derived from the available observations. (C) 2002 Published by Elsevier Science Ltd.

  • 39.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Bringfelt, B
    Johansson, C
    A model for vehicle-induced non-tailpipe emissions of particles along Swedish roads2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 33, p. 6088-6097Article in journal (Refereed)
    Abstract [en]

    One of the most important parameters that controls the suspension of road dust particles in the air is road surface moisture. This is calculated every hour from a budget equation that takes into account precipitation, evaporation and runoff. During wet conditions a road dust layer is built up from road wear which strongly depends on the use of studded tyres and road sanding. The dust layer is reduced during dry road conditions by suspension of particles due to vehicle-induced turbulence. The dust layer is also reduced by wash-off due to precipitation. Direct non-tailpipe vehicle emissions due to the wear and tear of the road surface, brakes and tyres are accounted for in the traditional way as constant emission factors expressed as mass emitted per vehicle kilometre. The model results are compared with measurements from both a narrow street canyon in the city centre of Stockholm and from an open highway outside the city. The model is able to account for the main features in the day-to-day mean PM10 variability for the street canyon and for the highway. A peak in the PM10 concentration is typically observed in late winter and early spring in the Nordic countries where studded tyres are used. This behaviour is due to a combination of factors: frequent conditions with dry roads, high number of cars with studded tyres and an accumulated road dust layer that increases suspension of particles. The study shows that using a constant emission factor for PM10 or relating PM10 emissions to NOx cannot be used for prediction of day-to-day variations in PM10 concentrations in the traffic environments studied here. The model needs to describe variations in dust load, wetness of the road and how dust suspension interacts with these processes. (c) 2005 Elsevier Ltd. All rights reserved.

  • 40. Petkov, Boyan H.
    et al.
    Vitale, Vito
    Tomasi, Claudio
    Siani, Anna Maria
    Seckmeyer, Gunther
    Webb, Ann R.
    Smedley, Andrew R. D.
    Casale, Giuseppe Rocco
    Werner, Rolf
    Lanconelli, Christian
    Mazzola, Mauro
    Lupi, Angelo
    Busetto, Maurizio
    Diemoz, Henri
    Goutail, Florence
    Koehler, Ulf
    Mendeva, Bogdana D.
    Josefsson, Weine
    SMHI, Core Services.
    Moore, David
    Lopez Bartolome, Maria
    Moreta Gonzalez, Juan Ramon
    Misaga, Oliver
    Dahlback, Arne
    Toth, Zoltan
    Varghese, Saji
    De Backer, Hugo
    Stuebi, Rene
    Vanicek, Karel
    Response of the ozone column over Europe to the 2011 Arctic ozone depletion event according to ground-based observations and assessment of the consequent variations in surface UV irradiance2014In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 85, p. 169-178Article in journal (Refereed)
    Abstract [en]

    The strong ozone depletion event that occurred in Arctic during spring 2011 was found to cause appreciable reduction in the ozone column (OC) in Europe, even at lower latitudes. The features of this episode have been analysed using the data recorded at 34 ground-based stations located in the European area and compared with the similar events in 2000 and 2005. The results provided evidence that OC as far south as 40 degrees N latitude was considerably influenced by the Arctic ozone loss in spring 2011. The reduction of OC at the northernmost sites was about 40% with respect to the mean value calculated over the previous six-year period, while a similar decrease at the southern extreme ranged between 15 and 18%, and were delayed by nearly two weeks compared to the Arctic region. The ozone distributions reconstructed for the West Europe sector show that the decline of OC lasted from late March to late April 2011. The echo of the Arctic ozone depletion on mid-latitude UV irradiance has been analysed trough model computations that show an increase of the midday erythemal dose by 3-4 SED (1 SED = 100 J m(-2)) that was slightly higher than at polar regions. On the other hand it was assessed that the biosystems in the northernmost regions were a subject of about 4 times higher UV stress than those at mid-latitudes. Despite indications of an OC recovery, the event examined here shows that the issue of ozone depletion episodes cannot be belittled. (C) 2013 Elsevier Ltd. All rights reserved.

  • 41. Potempski, S.
    et al.
    Galmarini, S.
    Addis, R.
    Astrup, P.
    Bader, S.
    Bellasio, R.
    Bianconi, R.
    Bonnardot, F.
    Buckley, R.
    D'Amours, R.
    van Dijk, A.
    Geertsema, G.
    Jones, A.
    Kaufmann, P.
    Pechinger, U.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Polreich, E.
    Prodanova, M.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Sorensen, J.
    Syrakov, D.
    Multi-model ensemble analysis of the ETEX-2 experiment2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 31, p. 7250-7265Article in journal (Refereed)
    Abstract [en]

    In this paper we investigate the results of multi-model simulations performed on the ETEX-2 experiment by the ENSEMBLE modelling community. New sets of results were created by taking different percentiles of the distribution of the models' predicted values. Both single models and the new constructed sets of results have been compared with the observed data. While a similar comparison for the ETEX-1 case indicated the median model was superior to any single model, for the ETEX-2 case, the situation is more difficult due to complex meteorological conditions, and no absolute and clear conclusions can be obtained. However, for emergency response purposes the median model still can be considered the most viable option also for complicated meteorological situation such is the ETEX-2 experiment. (c) 2008 Elsevier Ltd. All rights reserved.

  • 42.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Source function estimate by means of variational data assimilation applied to the ETEX-I tracer experiment1998In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 32, no 24, p. 4219-4225Article in journal (Refereed)
    Abstract [en]

    The ETEX data set opens new possibilities to develop data assimilation procedures in the area of long-range transport. This paper illustrates the possibilities using a variational approach, where the source term for ETEX-I was reconstructed. The MATCH model (Robertson et at., 1996) has been the basis for this attempt. The timing of the derived emission rates are in accordance with the time period for the ETEX-I release, and a cross validation, with observations beyond the selected assimilation period, shows that the source term gained holds for the entire ETEX-I experiment. A poor-man variational approach was shown to perform nearly as good as a fully variational data assimilation. The issue of quality control has not been considered in this attempt but will be an important part that has to be addressed in future work. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • 43. Silva, F. C.
    et al.
    Borrego, C.
    Keizer, J. J.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Verheijen, F. G. A.
    Effects of moisture content on wind erosion thresholds of biochar2015In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 123, p. 121-128Article in journal (Refereed)
    Abstract [en]

    Biochar, i.e. pyrolysed biomass, as a soil conditioner is gaining increasing attention in research and industry, with guidelines and certifications being developed for biochar production, storage and handling, as well as for application to soils. Adding water to biochar aims to reduce its susceptibility to become airborne during and after the application to soils, thereby preventing, amongst others, human health issues from inhalation. The Bagnold model has previously been modified to explain the threshold friction velocity of coal particles at different moisture contents, by adding an adhesive effect. However, it is unknown if this model also works for biochar particles. We measured the threshold friction velocities of a range of biochar particles (woody feedstock) under a range of moisture contents by using a wind tunnel, and tested the performance of the modified Bagnold model. Results showed that the threshold friction velocity can be significantly increased by keeping the gravimetric moisture content at or above 15% to promote adhesive effects between the small particles. For the specific biochar of this study, the modified Bagnold model accurately estimated threshold friction velocities of biochar particles up to moisture contents of 10%. (C) 2015 Elsevier Ltd. All rights reserved.

  • 44. Siniarovina, U
    et al.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    High-resolution model simulations of anthropogenic sulphate and sulphur dioxide in Southeast Asia2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 11, p. 2021-2034Article in journal (Refereed)
    Abstract [en]

    The Multiple-scale Atmospheric Transport and CHemical modelling system (MATCH)-driven by meteorological data from the ECMWF has been applied to a model domain covering Southeast Asia to complete a simulation extending over the full year of 2000. The current paper presents an evaluation of the model performance using archived chemical and meteorological data collected in the region during the year 2000. The calculated sulphate concentrations (on atmospheric aerosols and in precipitation) compare reasonably with observations while the atmospheric SO(2) mixing ratios show worse correspondence. This latter mismatch is attributed to local variations in the measured SO(2) concentrations that are not resolved in the regional model and possible miss-location of the emissions in our model. It can also be pointed out that different laboratories measuring SO(2) at the same site occasionally report SO(2) concentrations that differs by an order of magnitude or more. The seasonal variations of the modelled species are less than initially expected but generally in accordance with the measurements available. Most of the Malaysian cities have comparatively low concentrations of sulphate in precipitation. This is supported both by the model results and by independent measurements. From the model simulations and the measurements, it is concluded that the sulphur deposition is still relatively low (i.e. < 0.5 g sulphur m(-2) year(-1)) in most of rural Malaysia. This is also the case in Myanmar, Laos, central Vietnam, Kampuchea and southern Thailand. The situation in the vicinity of the large cities in the region is, however, much worse and the deposition is similar, or larger, than estimated critical loads. (c) 2005 Elsevier Ltd. All rights reserved.

  • 45. Solberg, S
    et al.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Laurila, T
    Lindskog, A
    Changes in Nordic surface ozone episodes due to European emission reductions in the 1990s2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 1, p. 179-192Article in journal (Refereed)
    Abstract [en]

    Based on analyses of model calculations with a regional scale CTM for two different years and measurement data from background locations in northern Europe, we have found several indications that peak ozone value, in the Nordic countries have been reduced during the 1990s as a result of reduced emissions of precursors in Europe. Official European emission data for 1999 gave a better model performance than the emission data for 1990 when modelling 1999 and 2000. A bootstrap resampling technique indicated that the improvement in performance was significant. The model predicted a reduction in peak ozone values of the order of 30 mug m(-3) due to European emission reductions during the 1990s in the Nordic countries. It is thus likely that the number of exceedances of hourly threshold values has been reduced, although the small number of episodes does not allow strict statements. The number and magnitude of the ozone episodes as well as the model performance was clearly higher for southern Sweden and Norway compared to Finland, presumably reflecting differences in meteorological transport and emission source regions. (C) 2004 Elsevier Ltd. All rights reserved.

  • 46.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Brannstrom, Niklas
    Persson, Christer
    SMHI, Professional Services.
    Grahn, Hakan
    von Schoenberg, Pontus
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Surface air quality implications of volcanic injection heights2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 166, p. 510-518Article in journal (Refereed)
  • 47. Toledano, C.
    et al.
    Cachorro, V. E.
    Gausa, M.
    Stebel, K.
    Aaltonen, V.
    Berjon, A.
    Ortiz de Galisteo, J. P.
    de Frutos, A. M.
    Bennouna, Y.
    Blindheim, S.
    Myhre, C. L.
    Zibordi, G.
    Wehrli, C.
    Kratzer, S.
    Håkansson, Bertil
    SMHI, Research Department, Oceanography.
    Carlund, Thomas
    SMHI, Core Services.
    de Leeuw, G.
    Herber, A.
    Torres, B.
    Overview of sun photometer measurements of aerosol properties in Scandinavia and Svalbard2012In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 52, p. 18-28Article in journal (Refereed)
    Abstract [en]

    An overview on the data of columnar aerosol properties measured in Northern Europe is provided. Apart from the necessary data gathered in the Arctic, the knowledge of the aerosol loading in nearby areas (e.g. sub-Arctic) is of maximum interest to achieve a correct analysis of the Arctic aerosols and transport patterns. This work evaluates data from operational sites with sun photometer measurements belonging either to national or international networks (AERONET, GAW-PFR) and programs conducted in Scandinavia and Svalbard. We enumerate a list of sites, measurement type and periods together with observed aerosol properties. An evaluation and analysis of aerosol data was carried out with a review of previous results as well. Aerosol optical depth (AOD) and Angstrom exponent (AE) are the current parameters with sufficient long-term records for a first evaluation of aerosol properties. AOD (500 nm) ranges from 0.08 to 0.10 in Arctic and sub-Arctic sites (Ny-Alesund: 0.09; Andenes: 0.10; Sodankyla: 0.08), and it is somewhat higher in more populated areas in Southern Scandinavia (AOD about 0.10-0.12 at 500 nm). On the Norwegian coast, aerosols show larger mean size (AE = 1.2 at Andenes) than in Finland, with continental climate (AE = 1.5 at Sodankyla). Columnar particle size distributions and related parameters derived from inversion of sun/sky radiances were also investigated. This work makes special emphasis in the joint and collaborative effort of the various groups from different countries involved in this study. Part of the measurements presented here were involved in the IPY projects Polar-AOD and POLARCAT. (C) 2011 Elsevier Ltd. All rights reserved.

  • 48. van Loon, M.
    et al.
    Vautard, R.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Graff, A.
    Jonson, J. E.
    Krol, M.
    Langner, J.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    White, L.
    Wind, P.
    Evaluation of long-term ozone simulations from seven regional air quality models and their ensemble2007In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 41, no 10, p. 2083-2097Article in journal (Refereed)
    Abstract [en]

    Long-term ozone simulations from seven regional air quality models, the Unified EMEP model, LOTOS-EUROS, CHIMERE, RCG, MATCH, DEHM and TM5, are intercompared and compared to ozone measurements within the framework of the EuroDelta experiment, designed to assess air quality improvement at the European scale in response to emission reduction scenarios for 2020. Modelled ozone concentrations for the year 2001 are evaluated. The models reproduce the main features of the ozone diurnal cycle, but generally overestimate daytime ozone, LOTOS-EUROS and RCG have a more pronounced diurnal cycle variation than observations, while the reverse occurs for TM5. CHIMERE has a large positive bias, which can be explained by a systematic bias in boundary conditions. The other models and the "ensemble model", whose concentrations are by definition averaged over all models, represent accurately the diurnal cycle. The ability of the models to simulate day-to-day daily ozone average or maxima variability is examined by means of percentiles, root mean square errors and correlations. In general, daily maxima are better simulated than daily averages, and summertime concentrations are better simulated than wintertime concentrations. Summertime correlations range between 0.5 and 0.7 for daily averages and 0.6 and 0.8 for daily maxima. Two health-related indicators are used, the number of days of exceedance of the 120 mu g m(-3) threshold for the daily maximal 8-h ozone concentration and the SOMO35. Both are well reproduced in terms of frequency, but the simultaneity of occurrence of exceedance days between observations and simulations is not well captured.

  • 49. Vautard, R.
    et al.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Foltescu, Valentin
    SMHI.
    Graff, A.
    Kerschbaumer, A.
    Krol, M.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    Wind, P.
    Skill and uncertainty of a regional air quality model ensemble2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 31, p. 4822-4832Article in journal (Refereed)
    Abstract [en]

    Recently several regional air quality projects were carried out to support the negotiation under the Clean Air For Europe (CAFE) programme by predicting the impact of emission control policies with an ensemble of models. Within these projects, CITYDELTA and EURODELTA, the fate of air quality at the scale of European cities or that of the European continent was studied using several models. In this article we focus on the results of EURODELTA. The predictive skill of the ensemble of models is described for ozone, nitrogen dioxide and secondary inorganic compounds, and the uncertainty in air quality modelling is examined through the model ensemble spread of concentrations. For ozone daily maxima the ensemble spread origin differs from one region to another. In the neighbourbood of cities or in mountainous areas the spread of predicted values does not span the range of observed data, due to poorly resolved emissions or complex-terrain meteorology. By contrast in Atlantic and North Sea coastal areas the spread of predicted values is found to be larger than the observations. This is attributed to large differences in the boundary conditions used in the different models. For NO2 daily averages the ensemble spread is generally too small compared with observations. This is because models miss highest values occurring in stagnant meteorology in stable boundary layers near cities. For secondary particulate matter compounds the simulated concentration spread is more balanced, observations falling nearly equiprobably within the ensemble, and the spread originates both from meteorology and aerosol chemistry and thermodynamics. (C) 2008 Published by Elsevier Ltd.

  • 50. Wang, Zifa
    et al.
    Xie, Fuying
    Sakurai, T.
    Ueda, H.
    Han, Zhiwei
    Carmichael, G. R.
    Streets, D.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Holloway, T.
    Hayami, H.
    Kajino, M.
    Thongboonchoo, N.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Park, S. U.
    Fung, C.
    Chang, A.
    Sartelet, K.
    Amann, M.
    MICS-Asia II: Model inter-comparison and evaluation of acid deposition2008In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 42, no 15, p. 3528-3542Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the comparison of chemical deposition of eight regional chemical models used in Model Inter-Comparison Study for Asia (MICS-Asia) II. Monthly-mean depositions of chemical species simulated by these models, including dry deposition of SO(2), HNO(3), NH(3), Sulfate, nitrate and ammonium and wet deposition of SO(4)(2-), NO(3)(-) and NH(4)(+), have been provided for four periods (March, July, December 2001 and March 2002) in this work. Observations at 37 sites of the Acid Deposition Monitoring Network in East Asia (EANET) are compared with SO(4)(2-), NO(3)(-) and NH(4)(+) wet deposition model results. Significant correlations appeared between the observation and computed ensemble mean of participant models. Also, differences among modeled sulfur and nitrogen dry depositions have been studied at the EANET sites. Based on the analysis of acid deposition for various species from different models, total depositions of sulfur (SO(2) and sulfate) and nitrogen (nitrate and ammonium) have been evaluated as the ensemble mean of the eight models. In general, all models capture the observed spatial distribution' of sulfur and nitrogen deposition, although the absolute values may differ from measurements. High deposition often occurs in eastern China, Japan, the Republic of Korea, Thailand, Vietnam, Philippines and other parts of Southeast Asia. The magnitude of model bias is quite large for many of the models. In examining the reasons for model-measurement disagreement, we find that differences in chemical processes, deposition parameterization, and modeled precipitation are the main reasons for large model disparities. (C) 2008 Elsevier Ltd. All rights reserved.

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