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  • 201. Lewinschal, Anna
    et al.
    Ekman, Annica M. L.
    Hansson, Hans-Christen
    Sand, Maria
    Berntsen, Terje K.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Local and remote temperature response of regional SO2 emissions2019In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 19, no 4, p. 2385-2403Article in journal (Refereed)
  • 202.
    Lövblad, Gun
    et al.
    IVL Swedish Environmental Research Institute.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Background report on air pollution situation in the Baltic states - a prefeasibility study: IVL Publikation B 10381991Report (Other academic)
  • 203. Mackowski, D. W.
    et al.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Mishchenko, M. I.
    A T matrix method based upon scalar basis functions2013In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, p. 113-121Article in journal (Refereed)
    Abstract [en]

    A surface integral formulation is developed for the T matrix of a homogenous and isotropic particle of arbitrary shape, which employs scalar basis functions represented by the translation matrix elements of the vector spherical wave functions. The formulation begins with the volume integral equation for scattering by the particle, which is transformed so that the vector and dyadic components in the equation are replaced with associated dipole and multipole level scalar harmonic wave functions. The approach leads to a volume integral formulation for the T matrix, which can be extended, by the use of Green's identities, to the surface integral formulation. The result is shown to be equivalent to the traditional surface integral formulas based on the VSWF basis. (C) 2013 Elsevier Ltd. All rights reserved.

  • 204. Maderich, V.
    et al.
    Bezhenar, R.
    Heling, R.
    de With, G.
    Jung, K. T.
    Myoung, J. G.
    Cho, Y-K
    Qiao, F.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Regional long-term model of radioactivity dispersion and fate in the Northwestern Pacific and adjacent seas: application to the Fukushima Dai-ichi accident2014In: Journal of Environmental Radioactivity, ISSN 0265-931X, E-ISSN 1879-1700, Vol. 131, p. 4-18Article in journal (Refereed)
    Abstract [en]

    The compartment model POSEIDON-R was modified and applied to the Northwestern Pacific and adjacent seas to simulate the transport and fate of radioactivity in the period 1945-2010, and to perform a radiological assessment on the releases of radioactivity due to the Fukushima Dai-ichi accident for the period 2011-2040. The model predicts the dispersion of radioactivity in the water column and in sediments, the transfer of radionuclides throughout the marine food web, and subsequent doses to humans due to the consumption of marine products. A generic predictive dynamic food-chain model is used instead of the biological concentration factor (BCF) approach. The radionuclide uptake model for fish has as a central feature the accumulation of radionuclides in the target tissue. The three layer structure of the water column makes it possible to describe the vertical structure of radioactivity in deep waters. In total 175 compartments cover the Northwestern Pacific, the East China and Yellow Seas and the East/Japan Sea. The model was validated from Cs-137 data for the period 1945-2010. Calculated concentrations of Cs-137 in water, bottom sediments and marine organisms in the coastal compartment, before and after the accident, are in close agreement with measurements from the Japanese agencies. The agreement for water is achieved when an additional continuous flux of 3.6 TBq y(-1) is used for underground leakage of contaminated water from the Fukushima Dai-ichi NPP, during the three years following the accident. The dynamic food web model predicts that due to the delay of the transfer throughout the food web, the concentration of Cs-137 for piscivorous fishes returns to background level only in 2016. For the year 2011, the calculated individual dose rate for Fukushima Prefecture due to consumption of fishery products is 3.6 mu Sv y(-1). Following the Fukushima Dai-ichi accident the collective dose due to ingestion of marine products for Japan increased in 2011 by a factor of 6 in comparison with 2010. (C) 2013 Elsevier Ltd. All rights reserved.

  • 205. Mahajan, Anoop S.
    et al.
    Fadnavis, Suvarna
    Thomas, Manu Anna
    SMHI, Research Department, Air quality.
    Pozzoli, Luca
    Gupta, Smrati
    Royer, Sarah-Jeanne
    Saiz-Lopez, Alfonso
    Simo, Rafel
    Quantifying the impacts of an updated global dimethyl sulfide climatology on cloud microphysics and aerosol radiative forcing2015In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 120, no 6, p. 2524-2536Article in journal (Refereed)
    Abstract [en]

    One of the critical parameters in assessing the global impacts of dimethyl sulfide (DMS) on cloud properties and the radiation budget is the estimation of phytoplankton-induced ocean emissions, which are derived from prescribed, climatological surface seawater DMS concentrations. The most widely used global ocean DMS climatology was published 15 years ago and has recently been updated using a much larger database of observations. The updated climatology displays significant differences in terms of the global distribution and regional monthly averages of sea surface DMS. In this study, we use the ECHAM5-HAMMOZ aerosol-chemistry-climate general circulation model to quantify the influence of the updated DMS climatology in computed atmospheric properties, namely, the spatial and temporal distributions of atmospheric DMS concentration, sulfuric acid concentration, sulfate aerosols, number of activated aerosols, cloud droplet number concentration, and the aerosol radiative forcing at the top of the atmosphere. Significant differences are observed for all the modeled variables. Comparison with observations of atmospheric DMS and total sulfate also shows that in places with large DMS emissions, the updated climatology shows a better match with the observations. This highlights the importance of using the updated climatology for projecting future impacts of oceanic DMS emissions, especially considering that the relative importance of the natural sulfur fluxes is likely to increase due to legislation to clean up anthropogenic emissions. The largest estimated differences are in the Southern Ocean, Indian Ocean, and parts of the Pacific Ocean, where the climatologies differ in seasonal concentrations over large geographical areas. The model results also indicate that the former DMS climatology underestimated the effect of DMS on the globally averaged annual aerosol radiative forcing at the top of the atmosphere by about 20%.

  • 206. Mahmood, Rashed
    et al.
    von Salzen, Knut
    Flanner, Mark
    Sand, Maria
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Wang, Hailong
    Huang, Lin
    Seasonality of global and Arctic black carbon processes in the Arctic Monitoring and Assessment Programme models2016In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 121, no 12, p. 7100-7116Article in journal (Refereed)
  • 207. Marecal, V.
    et al.
    Peuch, V. -H
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Andersson, S.
    Arteta, J.
    Beekmann, M.
    Benedictow, A.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Cansado, A.
    Cheroux, F.
    Colette, A.
    Coman, A.
    Curier, R. L.
    van der Gon, H. A. C. Denier
    Drouin, A.
    Elbern, H.
    Emili, E.
    Engelen, R. J.
    Eskes, H. J.
    Foret, G.
    Friese, E.
    Gauss, M.
    Giannaros, C.
    Guth, J.
    Joly, M.
    Jaumouille, E.
    Josse, B.
    Kadygrov, N.
    Kaiser, J. W.
    Krajsek, K.
    Kuenen, J.
    Kumar, U.
    Liora, N.
    Lopez, E.
    Malherbe, L.
    Martinez, I.
    Melas, D.
    Meleux, F.
    Menut, L.
    Moinat, P.
    Morales, T.
    Parmentier, J.
    Piacentini, A.
    Plu, M.
    Poupkou, A.
    Queguiner, S.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rouil, L.
    Schaap, M.
    Segers, A.
    Sofiev, M.
    Tarasson, L.
    Thomas, Manu Anna
    SMHI, Research Department, Air quality.
    Timmermans, R.
    Valdebenito, A.
    van Velthoven, P.
    van Versendaal, R.
    Vira, J.
    Ung, A.
    A regional air quality forecasting system over Europe: the MACC-II daily ensemble production2015In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, no 9, p. 2777-2813Article in journal (Refereed)
    Abstract [en]

    This paper describes the pre-operational analysis and forecasting system developed during MACC (Monitoring Atmospheric Composition and Climate) and continued in the MACC-II (Monitoring Atmospheric Composition and Climate: Interim Implementation) European projects to provide air quality services for the European continent. This system is based on seven state-of-the art models developed and run in Europe (CHIMERE, EMEP, EURAD-IM, LOTOS-EUROS, MATCH, MOCAGE and SILAM). These models are used to calculate multi-model ensemble products. The paper gives an overall picture of its status at the end of MACCII (summer 2014) and analyses the performance of the multi-model ensemble. The MACC-II system provides daily 96 h forecasts with hourly outputs of 10 chemical species/aerosols (O-3, NO2, SO2, CO, PM10, PM2.5, NO, NH3, total NMVOCs (non-methane volatile organic compounds) and PAN + PAN precursors) over eight vertical levels from the surface to 5 km height. The hourly analysis at the surface is done a posteriori for the past day using a selection of representative air quality data from European monitoring stations. The performance of the system is assessed daily, weekly and every 3 months (seasonally) through statistical indicators calculated using the available representative air quality data from European monitoring stations. Results for a case study show the ability of the ensemble median to forecast regional ozone pollution events. The seasonal performances of the individual models and of the multi-model ensemble have been monitored since September 2009 for ozone, NO2 and PM10. The statistical indicators for ozone in summer 2014 show that the ensemble median gives on average the best performances compared to the seven models. There is very little degradation of the scores with the forecast day but there is a marked diurnal cycle, similarly to the individual models, that can be related partly to the prescribed diurnal variations of anthropogenic emissions in the models. During summer 2014, the diurnal ozone maximum is underestimated by the ensemble median by about 4 mu g m(-3) on average. Locally, during the studied ozone episodes, the maxima from the ensemble median are often lower than observations by 30-50 mu g m(-3). Overall, ozone scores are generally good with average values for the normalised indicators of 0.14 for the modified normalised mean bias and of 0.30 for the fractional gross error. Tests have also shown that the ensemble median is robust to reduction of ensemble size by one, that is, if predictions are unavailable from one model. Scores are also discussed for PM10 for winter 2013-1014. There is an underestimation of most models leading the ensemble median to a mean bias of 4.5 mu g m(-3). The ensemble median fractional gross error is larger for PM10 (similar to 0.52) than for ozone and the correlation is lower (similar to 0.35 for PM10 and similar to 0.54 for ozone). This is related to a larger spread of the seven model scores for PM10 than for ozone linked to different levels of complexity of aerosol representation in the individual models. In parallel, a scientific analysis of the results of the seven models and of the ensemble is also done over the Mediterranean area because of the specificity of its meteorology and emissions. The system is robust in terms of the production availability. Major efforts have been done in MACC-II towards the operationalisation of all its components. Foreseen developments and research for improving its performances are discussed in the conclusion.

  • 208. Markakis, Konstantinos
    et al.
    Valari, Myrto
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Lacressonniere, Gwendoline
    Vautard, Robert
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Mid-21st century air quality at the urban scale under the influence of changed climate and emissions - case studies for Paris and Stockholm2016In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 16, no 4, p. 1877-1894Article in journal (Refereed)
    Abstract [en]

    Ozone, PM10 and PM2.5 concentrations over Paris, France and Stockholm, Sweden were modelled at 4 and 1 km horizontal resolutions respectively for the present and 2050 periods employing decade-long simulations. We account for large-scale global climate change (RCP-4.5) and fine-resolution bottom-up emission projections developed by local experts and quantify their impact on future pollutant concentrations. Moreover, we identify biases related to the implementation of regional-scale emission projections by comparing modelled pollutant concentrations between the fine-and coarse-scale simulations over the study areas. We show that over urban areas with major regional contribution (e.g. the city of Stockholm) the bias related to coarse-scale projections may be significant and lead to policy misclassification. Our results stress the need to better understand the mechanism of bias propagation across the modelling scales in order to design more successful local-scale strategies. We find that the impact of climate change is spatially homogeneous in both regions, implying strong regional influence. The climate benefit for ozone (daily mean and maximum) is up to 5% for Paris and 2% for Stockholm city. The climate benefit on PM2.5 and PM10 in Paris is between 5 and 10 %, while for Stockholm we estimate mixed trends of up to 3% depending on season and size class. In Stockholm, emission mitigation leads to concentration reductions up to 15% for daily mean and maximum ozone and 20% for PM. Through a sensitivity analysis we show that this response is entirely due to changes in emissions at the regional scale. On the contrary, over the city of Paris (VOC-limited photochemical regime), local mitigation of NO x emissions increases future ozone concentrations due to ozone titration inhibition. This competing trend between the respective roles of emission and climate change, results in an increase in 2050 daily mean ozone by 2.5% in Paris. Climate and not emission change appears to be the most influential factor for maximum ozone concentration over the city of Paris, which may be particularly interesting from a health impact perspective.

  • 209.
    Marmefelt, Eleonor
    et al.
    SMHI, Professional Services.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    An integrated biogeochemical model system for the Baltic Sea1999In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 393, p. 45-56Article in journal (Refereed)
    Abstract [en]

    The Swedish Meteorological and Hydrological Institute (SMHI) is developing an integrated biogeochemical model system for the Baltic Sea. It consists of three coupled models; a marine biogeochemical-hydrodynamical model (SCOBI), a continuous riverine nitrogen transport model (HBV-N) and an atmospheric transport and chemical model (MATCH). It is supplied with a tool for presentation and analysis. The SCOBI model is a coupled one-dimensional model with high vertical resolution. Horizontal variations are taken into account by dividing the area into smaller boxes. The model includes primary phytoplankton production, nitrogen fixation and secondary zooplankton production. Nitrogen load from land is obtained through the HBV-N model, which simulates organic and inorganic nitrogen separately in catchments. The model is based on the hydrological model HBV, and the subbasin runoff is simulated on a daily basis. The HBV-N model is calibrated and validated against measured concentrations and water flow in rivers. The atmospheric input of oxidised and reduced nitrogen is taken from the annual assessments carried out with the MATCH-Sweden modelling system. MATCH-Sweden combines model calculations, using an atmospheric transport and chemical model, with observations of air- and precipitation chemistry data to give a detailed mapping of concentrations and deposition of nitrogen compounds over Sweden. Supplemented with monitoring data for the specific area of interest, the integrated biogeochemical model system makes a useful tool for environmental protection analyses; e.g. for interpretation of monitoring data as well as creating scenarios for studies of effects in changes of the nutrient loads.

  • 210. Martinsson, Johan
    et al.
    Azeem, Hafiz Abdul
    Sporre, Moa K.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Ahlberg, Erik
    Ostrom, Emilie
    Kristensson, Adam
    Swietlicki, Erik
    Stenstrom, Kristina Eriksson
    Carbonaceous aerosol source apportionment using the Aethalometer model - evaluation by radiocarbon and levoglucosan analysis at a rural background site in southern Sweden2017In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 6, p. 4265-4281Article in journal (Refereed)
  • 211. Mauno, Paivi
    et al.
    McFarquhar, Greg M.
    Raisanen, Petri
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Timlin, Michael S.
    Nousiainen, Timo
    The influence of observed cirrus microphysical properties on shortwave radiation: A case study over Oklahoma2011In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 116, article id D22208Article in journal (Refereed)
    Abstract [en]

    The shortwave radiative effect of an ice cloud observed over the Atmospheric Radiation Measurement program's Southern Great Plains site in Oklahoma is investigated. Airborne microphysical data from a cloud particle imager, optical array probes, and forward scattering probes are used to construct vertical profiles of the size and shape distributions of ice crystals. Due to uncertainties associated with measuring the sizes and shapes of small ice crystals with maximum dimensions less than 120 mu m, five alternate size-shape distributions are derived and combined with existing databases of wavelength-dependent single-scattering properties of idealized ice crystals to obtain vertical profiles of optical properties. The dependence of the surface and the top-of-the-atmosphere fluxes on these uncertainties is simulated with a radiative transfer model. In addition, surface fluxes are compared against measurements at the surface. It is found that the differences between the modeled and measured fluxes are too large to be explained by uncertainties in the shape and concentrations of small ice crystals. Sensitivity tests suggest that the discrepancies occur because the real optical thickness is larger than that derived from the aircraft profiles most of the time. When the optical thickness was derived based on modeled and measured direct fluxes, the modeled total downward flux agreed well with the measurements. Slightly (less than 10%) reducing the asymmetry parameter, which is possibly associated with the presence of surface roughness, air bubble inclusions or other nonidealities in ice crystals, may further improve the agreement with observations.

  • 212. McFiggans, Gordon
    et al.
    Mentel, Thomas F.
    Wildt, Juergen
    Pullinen, Iida
    Kang, Sungah
    Kleist, Einhard
    Schmitt, Sebastian
    Springer, Monika
    Tillmann, Ralf
    Wu, Cheng
    Zhao, Defeng
    Hallquist, Mattias
    Faxon, Cameron
    Le Breton, Michael
    Hallquist, Asa M.
    Simpson, David
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Jenkin, Michael E.
    Ehn, Mikael
    Thornton, Joel A.
    Alfarra, M. Rami
    Bannan, Thomas J.
    Percival, Carl J.
    Priestley, Michael
    Topping, David
    Kiendler-Scharr, Astrid
    Secondary organic aerosol reduced by mixture of atmospheric vapours2019In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 565, no 7741, p. 587-593Article in journal (Refereed)
  • 213. Merikallio, S.
    et al.
    Lindqvist, H.
    Nousiainen, T.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Modelling light scattering by mineral dust using spheroids: assessment of applicability2011In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 11, no 11, p. 5347-5363Article in journal (Refereed)
    Abstract [en]

    We study the applicability of spheroidal model particles for simulating the single-scattering optical properties of mineral dust aerosols. To assess the range of validity of this model, calculations are compared to laboratory observations for five different dust samples at two wavelengths. We further investigate whether the best-fit shape distributions of spheroids for different mineral dust samples have any similarities that would allow us to suggest a generic first-guess shape distribution for suspended mineral dust. We find that best-fit shape distributions vary considerably between samples and even between wavelengths, making definitive suggestions for a shape distribution difficult. The best-fit shape distribution also depends strongly on the refractive index assumed and the cost function adopted. However, a power-law shape distribution which favours those spheroids that depart most from the spherical shape is found to work well in most cases. To reproduce observed asymmetry parameters, best results are obtained with a power-law shape distribution with an exponent around three.

  • 214. Merikallio, S.
    et al.
    Nousiainen, T.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Harri, A. -M
    Light scattering by the Martian dust analog, palagonite, modeled with ellipsoids2013In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 21, no 15, p. 17972-17985Article in journal (Refereed)
    Abstract [en]

    We have investigated the suitability of the ellipsoidal model particles to mimic scattering by Martian dust particles by comparing simulations against laboratory data for palagonite, a Mars analog sample. By optimizing the shape distribution of ellipsoids, a very good match with a laboratory-measured scattering matrix was obtained. Even an equiprobable distribution of ellipsoids performed well. The asymmetry parameter and single-scattering albedo were found to depend on the assumed shape distribution as much as on the typical uncertainties associated with refractive indices and size, suggesting that shape is an important parameter that potentially influences remote retrievals of dust particle properties. (C) 2013 Optical Society of America

  • 215.
    Meuller, Lars
    et al.
    SMHI.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Andersson, E.
    SMHI.
    Gustavsson, Nils
    Meterologi.
    Meso-g scale objective analysis of near surface temperature, humidity and wind, and its application in air pollution modelling1990Report (Other academic)
  • 216. Miranda, A.I
    et al.
    Martins, Helena
    SMHI, Research Department, Climate research - Rossby Centre.
    Valente, J.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Borrego, C.
    Tavares, R.
    Samson, R.
    del Amo, R.A.
    Case Studies: Modeling the Atmospheric Benefits of Urban Greening2017In: The Urban Forest - Cultivating Green Infrastructure for People and the Environment / [ed] D. Pearlmutter, C. Calfapietra, R. Samson, L. O'Brien, S.K. Ostoić, G. Sanesi, R.A. del Amo, Springer International Publishing , 2017, p. 89-99Chapter in book (Refereed)
  • 217. Mishchenko, Michael I.
    et al.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Mackowski, Daniel W.
    Wriedt, Thomas
    Peter Waterman and his scientific legacy2013In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, p. 1-1Article in journal (Other academic)
  • 218. Monks, S. A.
    et al.
    Arnold, S. R.
    Emmons, L. K.
    Law, K. S.
    Turquety, S.
    Duncan, B. N.
    Flemming, J.
    Huijnen, V.
    Tilmes, S.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Mao, J.
    Long, Y.
    Thomas, J. L.
    Steenrod, S. D.
    Raut, J. C.
    Wilson, C.
    Chipperfield, M. P.
    Diskin, G. S.
    Weinheimer, A.
    Schlager, H.
    Ancellet, G.
    Multi-model study of chemical and physical controls on transport of anthropogenic and biomass burning pollution to the Arctic2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 6, p. 3575-3603Article in journal (Refereed)
    Abstract [en]

    Using observations from aircraft, surface stations and a satellite instrument, we comprehensively evaluate multi-model simulations of carbon monoxide (CO) and ozone (O-3) in the Arctic and over lower latitude emission regions, as part of the POLARCAT Model Inter-comparison Project (POLMIP). Evaluation of 11- atmospheric models with chemistry shows that they generally underestimate CO throughout the Arctic troposphere, with the largest biases found during winter and spring. Negative CO biases are also found throughout the Northern Hemisphere, with multi-model mean gross errors (9-12%) suggesting models perform similarly over Asia, North America and Europe. A multi-model annual mean tropospheric OH (10.8 +/- 0.6 x 10(5) molec cm(-3)) is found to be slightly higher than previous estimates of OH constrained by methyl chloroform, suggesting negative CO biases in models may be improved through better constraints on OH. Models that have lower Arctic OH do not always show a substantial improvement in their negative CO biases, suggesting that Arctic OH is not the dominant factor controlling the Arctic CO burden in these models. In addition to these general biases, models do not capture the magnitude of CO enhancements observed in the Arctic free troposphere in summer, suggesting model errors in the simulation of plumes that are transported from anthropogenic and biomass burning sources at lower latitudes. O-3 in the Arctic is also generally underestimated, particularly at the surface and in the upper troposphere. Summer O-3 comparisons over lower latitudes show several models overestimate upper tropospheric concentrations. Simulated CO, O-3 and OH all demonstrate a substantial degree of inter-model variability. Idealised CO-like tracers are used to quantitatively compare the impact of inter-model differences in transport and OH on CO in the Arctic troposphere. The tracers show that model differences in transport from Europe in winter and from Asia throughout the year are important sources of model variability at Barrow. Unlike transport, inter-model variability in OH similarly affects all regional tracers at Barrow. Comparisons of fixed-lifetime and OH-loss idealised CO-like tracers throughout the Arctic troposphere show that OH differences are a much larger source of inter-model variability than transport differences. Model OH concentrations are correlated with H2O concentrations, suggesting water vapour concentrations are linked to differences in simulated concentrations of CO and OH at high latitudes in these simulations. Despite inter-model differences in transport and OH, the relative contributions from the different source regions (North America, Europe and Asia) and different source types (anthropogenic and biomass burning) are comparable across the models. Fire emissions from the boreal regions in 2008 contribute 33, 43 and 19% to the total Arctic CO-like tracer in spring, summer and autumn, respectively, highlighting the importance of boreal fire emissions in controlling pollutant burdens in the Arctic.

  • 219. Nousiainen, T
    et al.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Veihelmann, B
    Light scattering modeling of small feldspar aerosol particles using polyhedral prisms and spheroids2006In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 101, no 3, p. 471-487Article in journal (Refereed)
    Abstract [en]

    The use of simplified particle shapes for modeling scattering by irregularly shaped mineral-dust particles is studied using polyhedral prisms and spheroids as model particles. Simulated phase matrices averaged over shape and size distributions at wavelength 633 nm are compared with a laboratory-measured phase matrix of feldspar particles with known size distribution with effective radius of 1.0 mu m. When an equi-probable shape distribution is assumed, prisms and oblate spheroids agree with measurements to a similar degree, whereas prolate spheroids perform markedly better. Both spheroids and prisms perform much better than spheres. When ail automatic fitting method is applied for finding optimal shape distributions, it is found that the most elongated spheroids are most important for good fits, whereas nearly-spherical spheroids are generally of very little importance. The phase matrices for the different polyhedral prisms, on the other hand, are found to be similar, thus their shape-averaged phase matrices are insensitive to the shape distribution assumed. For spheroids, a simple parameterization for the shape distribution, where weights increase with increasing departure from spherical shape, is proposed and tested. This parameterization improves the fit of most phase matrix elements attained with an equi-probable shape distribution, and it performs particularly well for reproducing the measured phase function. (c) 2006 Elsevier Ltd. All rights reserved.

  • 220. Nousiainen, Timo
    et al.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Lindqvist, Hannakaisa
    Can particle shape information be retrieved from light-scattering observations using spheroidal model particles?2011In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 112, no 13, p. 2213-2225Article in journal (Refereed)
    Abstract [en]

    We address the question if and how observations of scattered intensity and polarisation can be employed for retrieving particle shape information beyond a simple classification into spherical and nonspherical particles. To this end, we perform several numerical experiments, in which we attempt to retrieve shape information of complex particles with a simple nonspherical particle model based on homogeneous spheroids. The discrete dipole approximation is used to compute reference phase matrices for a cube, a Gaussian random sphere, and a porous oblate and prolate spheroid as a function of size parameter. Phase matrices for the model particles, homogeneous spheroids, are computed with the T-matrix method. By assuming that the refractive index and the size distribution is known, an optimal shape distribution of model particles is sought that best matches the reference phase matrix. Both the goodness of fit and the optimal shape distribution are analysed. It is found that the phase matrices of cubes and Gaussian random spheres are well reproduced by the spheroidal particle model, while the porous spheroids prove to be challenging. The "retrieved" shape distributions, however, do not correlate well with the shape of the target particle even when the phase matrix is closely reproduced. Rather, they tend to exaggerate the aspect ratio and always include multiple spheroids. A most likely explanation why spheroids succeed in mimicking phase matrices of more irregularly shaped particles, even if their shape distributions display little similarity to those of the target particles, is that by varying the spheroids' aspect ratio one covers a large range of different phase matrices. This often makes it possible to find a shape distribution of spheroids that matches the phase matrix of more complex particles. (C) 2011 Elsevier Ltd. All rights reserved.

  • 221. Nousiainen, Timo
    et al.
    Zubko, Evgenij
    Lindqvist, Hannakaisa
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Tyynela, Jani
    Comparison of scattering by different nonspherical, wavelength-scale particles2012In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 113, no 18, p. 121-135Article in journal (Refereed)
    Abstract [en]

    It is well established that spherical and nonspherical particles scatter light differently. There are a large number of studies where scattering properties of different nonspherical particles are studied. Here we study to what degree scattering matrices of different nonspherical particles resemble each other, and whether there are significant correlations between morphological similarity and similar single-scattering properties. Altogether 15 different shapes are considered, including both irregular and regular shapes as well as homogeneous and inhomogeneous particles. For all nonspherical particles, orientation- and ensemble-averaged scattering properties are considered, and variability within each ensemble is ignored. The results reveal that different nonspherical shapes have surprisingly similar phase functions. An analysis of the asymmetry parameter reveals that the resemblance is, however, only qualitative: the phase functions are featureless and predominantly flat at side scattering, but they are nevertheless different. The degree of linear polarization for unpolarized incident light shows much larger differences among the shapes, albeit it is much more positive for all nonspherical targets than for Mie spheres. Similar to the phase function, the depolarization ratio tends to be similar among the nonspherical particle types, implying that the strength of depolarization cannot be used as a measure for the type of nonsphericity. In general, it is found that there does not seem to be a clear correlation between particle morphology and scattering properties. (C) 2012 Elsevier Ltd. All rights reserved.

  • 222. 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.

  • 223. Olivares, Gustavo
    et al.
    Strom, Johan
    Johansson, Christer
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Estimates of black carbon and size-resolved particle number emission factors from residential wood burning based on ambient monitoring and model simulations2008In: JOURNAL OF THE AIR & WASTE MANAGEMENT ASSOCIATION, ISSN 1096-2247, Vol. 58, no 6, p. 838-848Article in journal (Refereed)
    Abstract [en]

    In this paper we derive typical emission factors for coarse particulate matter (PM10), oxides of nitrogen (NOx), black carbon (BC), and number particle size distributions based on a combination of measurements and air quality dispersion modeling. The advantage of this approach is that the emission factors represent integrated emissions from several vehicle types and different types of wood stoves. Normally it is very difficult to estimate the total emissions in cities on the basis of laboratory measurements on single vehicles or stoves because of the large variability in conditions. The measurements were made in Temuco, Chile, between April 18 and June 15, 2005 at two sites. The first one was located in a residential area relatively far from major roads. The second site was located in a busy street in downtown Temuco where wood consumption is low. The measurements support the assumption that the monitoring sites represent the impact of different emission sources, namely traffic and residential wood combustion (RWC). Fitting model results to the available measurements, emission factors were obtained for PM,, (RWC = 2160 +/- 100 mg/kg; traffic = 610 +/- 51 mg/veh-km), NOx (RWC = 800 +/- 100 mg/kg; traffic 4400 +/- 100 mg/veh-km), BC (RWC 74 +/- 6 mgjkg; traffic = 60 +/- 3 mg/veh-km) and particle number (N) with size distribution between 25 and 600 nm (N25-600) (RWC = 8.9 +/- 1 x 10(14) pt/kg; traffic = 6.7 +/- 0.5 x 10(14) pt/veh-km). The obtained emission factors are comparable to results reported in the literature. The size distribution of the N emission factors for traffic was shown to be different than for RWC. The main difference is that although traffic emissions show a bimodal size distribution with a main mode below 30 nm and a secondary one around 100 nm, RWC emissions show the main mode slightly below 100 nm and a smaller nucleation mode below 50 nm.

  • 224.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Gamerith, Valentin
    Gruber, Gunter
    Hoppe, Holger
    Kutschera, Peter
    Downscaling of Short-Term Precipitation from Regional Climate Models for Sustainable Urban Planning2012In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 4, no 5, p. 866-887Article in journal (Refereed)
    Abstract [en]

    A framework for downscaling precipitation from RCM projections to the high resolutions in time and space required in the urban hydrological climate change impact assessment is outlined and demonstrated. The basic approach is that of Delta Change, developed for both continuous and event-based applications. In both cases, Delta Change Factors (DCFs) are calculated which represent the expected future change of some key precipitation statistics. In the continuous case, short-term precipitation from climate projections are analysed in order to estimate DCFs associated with different percentiles in the frequency distribution of non-zero intensities. The DCFs may then be applied to an observed time series, producing a realisation of a future time series. The event-based case involves downscaling of Intensity-Duration-Frequency (IDF) curves based on extreme value analysis of annual maxima using the Gumbel distribution. The resulting DCFs are expressed as a function of duration and frequency (i.e., return period) and may be used to estimate future design storms. The applications are demonstrated in case studies focusing on the expected changes in short-term precipitation statistics until 2100 in the cities of Linz (Austria) and Wuppertal (Germany). The downscaling framework is implemented in the climate service developed within the EU-project SUDPLAN.

  • 225.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    An operational air pollution model1988Report (Other academic)
    Abstract [en]

    This report describes an operational air pollution medel developed at the Swedish Meteorological and Hydrological Institut for the prediction of air pollution concentrations on a local scale. Predictions can be roade in one or several receptor points for emissions from point, area- and traffic sources. The medel is partly based on the Danish so calledOML-model (Berkowicz et al.,1985).

  • 226.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    An operational air pollution model using routine meteorological data1984Report (Other academic)
  • 227.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Spridning av luftförorening från skorsten i konvektiva gränsskikt1982Report (Other academic)
  • 228.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Utvärdering av PM10-mätningar i några olika nordiska trafikmiljöer2006Report (Other academic)
    Abstract [sv]

    I denna rapport undersöks halterna av PM10 för några olika trafikmiljöer i Norden, nämligen Hornsgatan i Stockholm, Jagtvej i Köpenhamn och Runebergsgatan i Helsingfors. Alla tre är slutna gaturum där relationen hushöjd/gatubredd är nära ett. Resultaten av undersökningen kan sammanfattas på följande sätt:- Skillnaderna i PM10-halterna mellan Hornsgatan och Jagtvej är betydande. Det lokala haltbidraget, räknat som 90-percentil, är ca fyra gånger större vid Hornsgatan. Orsaken är främst att dubbdäck och sand används vid Hornsgatan men ej vid Jagtvej, vilket kraftigt ökar vägslitaget.- SMHIs emissionsmodell (Omstedt et al., 2005) ger god överensstämmelse med mätdata för Hornsgatan för såväl år 2000 som år 2004.- För Jagtvej finns det en stark korrelation mellan lokala PM10- och lokala NOx-halter. De lokala PM10-halterna beror därför främst på trafiken och inte så mycket på vägbanans egenskaper. Modelleringen kan därigenom förenklas genom att använda en konstant emissionsfaktor.- PM10-halterna vid Hornsgatan och Runebergsgatan liknar varandra med starka årstidsvariationer och höga halter under senvinter/vår, som är typiska för nordiska trafikmiljöer där dubbdäck används.- För Runebergsgatan beskriver SMHIs emissionsmodell relativt väl det generella halt mönstret. Dock överskattas emissionerna vid snösmältning. En naturlig förbättring är därför att inkludera snösmältning i modellen, vilket föreslås göras i en kommande studie.

  • 229.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    VEDAIR - ett internetverktyg för bedömning av luftkvalitet vid småskalig biobränsleeldning: Modellbeskrivning och slutrapport mars 20072007Report (Other academic)
    Abstract [en]

    This report describes a new internet tool for evaluation of air quality in residential areas with small scale wood-combustion. The work has been sponsored by the Swedish Energy Agency and the internet tool is called VEDAIR. The background is a four-year’s research program (2001-2004) called Biomass Combustion Health and Environment. Some conclusions from this program were that emissions from small scale wood-combustion can influence human health manly due to high emitting old wood stoves during cold whether conditions and that the air quality in such areas can improve significantly if old wood stoves were replaced by modern woodboilers attached to a storage tank or with a pellet boiler.

  • 230.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Vintervägar med eller utan dubbdäck: Beräkningar av emissioner och halter av partiklar för olika dubbdäcksscenarier2008Report (Other academic)
    Abstract [sv]

    Vårt klimat har stor inverkan på luftkvaliteten. Under vintermånaderna är temperaturen i hela landet ofta

  • 231.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Asker, Christian
    SMHI, Professional Services.
    Jones, Jörgen
    SMHI, Professional Services.
    Kindell, Sven
    SMHI, Professional Services.
    Segersson, David
    SMHI, Research Department, Air quality.
    Luftkvalitet i Sverige år 2020: Uppföljning av miljökvalitetsmålet Frisk luft för trafikmiljöer i svenska tätorter2012Report (Other academic)
    Abstract [sv]

    Luftföroreningar är ett lokalt men också gränsöverskridande problem. Sveriges luftkvalitet påverkas av lokala utsläppskällor, men även av långdistans-transport från stora emissionsområden i Europa. Utsläppen av många luftföroreningar har minskat under de senaste årtiondena på grund av kontinuerligt skärpta emissionskrav och betydande förbättringar har gjorts för vägtransportsektorns reglerade avgasemissioner. Fortsatt minskningar är att förvänta som också påverkar luftkvaliteten. Trots kraftiga minskningar av utsläppen både i Sverige och övriga Europa har inte luftkvaliteten i våra städer, med avseende på kvävedioxid (NO2), ozon (O3) och partiklar (PM10), förbättrats på något avgörande sätt sedan år 2000. Fortfarande är luftföroreningshalterna i många trafikmiljöer höga såväl i Sverige som i övriga Europa. Syftet med projektet är att ge underlag för bedömningar av hur miljökvalitetsmålet Frisk luft uppfylls i svenska tätorter och påvisa effekter av vad olika åtgärder, såväl internationellt som i Sverige och lokalt i kommuner, kan komma att få för effekter på luftkvaliteten år 2020.

  • 232.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Johansson, Christer
    Institutionen för tillämpad miljövetenskap (ITM), Stockholms universitet.
    Kartläggning av partiklar i Sverige - halter, källbidrag och kunskapsluckor2010Report (Other academic)
    Abstract [sv]

    Bakgrund och syfte. År 1999 startade Naturvårdsverket ett projekt för kartläggning av partikelhalter i Sverige samt identifikation av de viktigaste källorna. Kartläggningsprojektet byggde på mätningar under två år (1999-2001). Resultaten har varit till stor nytta och legat till grund för bland annat införande av nya miljömål och miljökvalitetsnormer, åtgärdsförslag och vetenskapliga publikationer. För första gången kunde haltnivåer av PM10 och PM2.5 beskrivas systematiskt i regional och urban bakgrund samt gaturum i Sverige. Tre huvudkällor till höga partikelhalter i Sverige kunde identifieras; långdistanstransport, uppvirvling av vägdamm och vedeldning.Sedan dess har kunskapen om partiklar ökat. Miljökvalitetsnormer har införts i Sverige och miljömål har formulerats. Idag finns mer mätdata tillgängliga och för vissa områden finns även längre tidsserier. Intresset för sjöfartens bidrag till luftföroreningar och partiklar har ökat, eftersom dess relativa bidrag jämfört med landbaserade emissioner ökar. Nya studier inriktade på förståelse av olika processer har genomförts. Modeller har utvecklats och förbättrats, därigenom har också möjligheten att kvantifiera olika källors bidrag ökat. Behovet att använda modeller i arbetet med miljömål och miljökvalitetsnormer har också blivit större.Syftet med denna studie är att presentera huvuddragen av den kunskap som kommit fram under de senaste tio åren om partikelhalter i Sverige, framförallt PM10 och PM2.5, men också peka på kunskapsluckor.

  • 233.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Dagens och framtidens luftkvalitet i Sverige: Haltberäkningar av NO2, PM10 och PM2.5 i svenska trafikmiljöer för framtidsscenarier med minskade europeiska emissioner2010Report (Other academic)
    Abstract [sv]

    Luftföroreningar är ett lokalt men också gränsöverskridande problem. Sveriges luftkvalitet påverkas av lokala utsläppskällor, men även av långdistanstransport från stora emissionsområden i Europa. Utsläppen av många luftföroreningar har minskat kraftigt under de senaste årtiondena på grund av kontinuerligt skärpta emissionskrav. Betydande förbättringar har bland annat gjorts inom vägtransportsektorn. Via europeiska utsläppsnormer definieras acceptabla gränser för avgasutsläpp för nya fordon som säljs i EUs medlemsstater. Dessa, och andra, utsläppskrav kommer att leda till fortsatt minskande emissioner i Europa och därmed även lägre föroreningsnivåer i den luft som kommer in över Sverige. Hur stort är det kvarstående behovet av lokala åtgärder i Sverige för att minska haltnivåerna till en nivå där normer och miljömål uppfylls? Det är en av de frågeställningar som denna rapport utgår från.Den lokala miljö som undersöks är gaturum, varför förändringar av vägtrafikens emissioner och halter i Sverige är central. Liknande emissionstrender, som i Europa, finns också i Sverige, med kraftigt minskande emissioner beroende bland annat på de europeiska utsläppsnormerna. Viktiga skillnader finns också. Vårt kalla svenska vinterklimat skapar bland annat hala vägbanor och ogynnsamma spridningsförhållanden. Åtgärder för att undvika hala vägbanor leder till ökat vägslitage och vägdamm som ackumuleras i vägmiljön, vilket i sin tur leder till höga partikelhalter. I norra delarna av Sverige skapas under vintern ogynnsamma spridningsförhållanden med stabil skiktning och låga inversioner. I kombination med höga emissioner av luftföroreningar från bostadsuppvärmning och kallstarter leder detta till höga halter av bland annat kväveoxider.Trots kraftiga minskningar av utsläppen både i Sverige och övriga Europa har inte luftkvaliteten, med avseende på kvävedioxid (NO2), ozon (O3) och partiklar (PM10 respektive PM2.5), förbättrats på något avgörande sätt sedan år 2000. Fortfarande är luftföroreningshalterna i många trafikmiljöer höga såväl i Sverige som i övriga Europa. Orsakerna till det diskuteras i rapporten. Syftet med denna undersökning är att analysera hur framtidens luftkvalitet på lokal nivå (gaturum) kan komma att utvecklas på grund av troliga emissionsminskningar i Europa och i Sverige, samt att bedöma hur stora lokala åtgärder som ytterligare kan komma att fordras för att klara miljökvalitetsnormer och miljömål.

  • 234.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Johansson, Christer
    ITM Stockholms Universitet.
    Löfgren, Bengt-Erik
    ÄFAB.
    Luftkvalitet och småskalig biobränsleeldning: Tillämpningar av SIMAIRved för några kommuner2008Report (Other academic)
    Abstract [en]

    SIMAIRrwc is a Web based evaluation tool for meeting the EU directive on air pollution limits in residential areas using wood combustion. The background is a four-year research program (2001-2004) called Biomass Combustion Health and Environment. Some conclusions from this program were that emissions from small scale wood combustion can influence human health mainly due to high emitting old wood stoves during cold weather conditions and that the air quality in such areas can improve significantly if old wood stoves were replaced by modern wood boilers attached to a storage tank or with a pellet boiler. SIMAIRrwc is based on the same principles as SIMAIRroad, which is a Web based evaluation tool for road traffic i.e. coupled model system using different models on local, urban and regional geographical scales, best available emission data, but at the same time presented in a very simplified way. In this project SIMAIRrwc has been applied in five different Swedish municipalities. The aim has been to apply and improve the model in cooperation with the municipalities. The conclusions from the project are:- Small scale wood combustions in residential areas are local problems which sometimes include only a few houses and/or wood-burners.- Air quality problems related to the EU directive are mainly due to particles.- Combinations of residential areas with wood combustion and emissions from nearby dense traffic roads might give rise to bad air quality.- Actions require knowledge about individual equipment which needs information from the local chimneysweeps.- The best way to identify problem areas is to use model calculations.- If model calculations indicate risks of exceeding air quality limits, then new calculations should be made withimproved input data taking into account for example information of district heating or other installations thatcan effect the emissions.• Before actions are taken it may also be useful to make measurements. The measurement site can then beselected in the area where the model calculations show the larges impact.• SIMAIRrwc is a powerful tool that can be used for identification and visualisation of areas where there mightbe air quality problems due to residential wood combustion.

  • 235.
    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.

  • 236.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Burman, L.
    SLB-analys.
    Beräkningar av kväveoxidhalter vid några gator i Umeå åren 2014 och 2022 med och utan miljözon2012Report (Other academic)
    Abstract [sv]

    Mätningar av kvävedioxid i Umeå har visat på halter som överskridit miljökvalitetsnormen. Den mest utsatta gatan är Västra Esplanaden men även utmed Östra Kyrkogatan har normen överskridits. För att minska halterna av kvävedioxid i Umeå centrum finns tankar på att inrätta miljözon. I denna rapport är tre beräkningspunkter valda utifrån gällande förutsättningar. Två av mätpunkterna ligger på Järnvägsallén respektive Östra Kyrkogatan, vilka finns inom tilltänkt zon. Den tredje ligger på Västra Esplanaden som gränsar mot zonen. De sträckor som beräknas är de mest trafikerade gatorna i Umeå centrum. I beräkningarna har hänsyn tagits till lika trafikförutsättningar och flöden för de redovisade åren.De beräkningar som redovisas i denna rapport baseras på modeller som beskriver dagens kunskap om emissioner, spridning och kemiska processer och med indata från olika alternativa trafikutvecklingar. I alla dessa delar finns det osäkerheter och felkällor som är svåra att kvantifiera. Det finns risk att emissionsutvecklingen för NOx mellanåren 2010 och 2020 är något för optimistiskt beräknad. Miljözonsberäkningarna förutsätter 100 % efterlevnad av regelverket.Nedan redovisas de viktigaste slutsatserna från beräkningarna.Västra EsplanadenUtan miljözon uppskattas halterna underskrida miljökvalitetsnormen efter år 2019. Med miljözon uppskattas halterna underskrida miljökvalitetsnormen efter år 2017, dvs. två år tidigare än utan miljözon.Järnvägsallén och Östra KyrkogatanHalterna beräknas vara något högre på Östra Kyrkogatan jämfört med Järnvägsallén. Vid Östra Kyrkogatan beräknas halterna överskrida miljökvalitetsnormen år 2010. Miljökvalitetsnormen för båda gatorna klaras såväl med som utan miljözon år 2014. Med miljözon minskar halterna jämfört utan miljözon.

  • 237.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Forsberg, Bertil
    Umeå Universitet.
    Nerhagen, Lena
    Länsstyrelsen Dalarnas Län.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Andersson, Stefan
    Umeå Universitet.
    SIMAIRscenario - ett modellverktyg för bedömning av luftföroreningars hälsoeffekter och kostnader2011Report (Other academic)
    Abstract [en]

    SIMAIRscenario is a new web based tool developed for estimation of health impacts and economic benefits occurring when populations experience changes in air quality. It is a new member of the SIMAIR family, which is a national air quality system for Sweden. In SIMAIRscenario following can be done: 1. Import air quality data fields from different dispersion models such as SIMAIR and Airviro. 2. Process air quality data by different mathematical operators. 3. Import and store detailed population data and process them by different mathematical operators. Population data for the year 2008 divided in different age groups with the resolution of 100*100 meters for the whole country is now available. 4. Presentation of air quality and population data on maps. 5. Perform exposure calculations and presents results on maps and in tables. 6. Perform health impact assessments and valuation of these impacts in monetary terms. The air quality change is calculated as the difference between the starting air pollution level, also called the baseline, and the air pollution level after some change, also called the scenario. The scenario can be described as a major change in activities or technical solutions in an urban or regional area or a regulation leading to different emissions to the atmosphere compare to the baseline.

  • 238.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Forsberg, Bertil
    Umeå Universitet.
    Persson, Karin
    IVL Svenska Miljöinstitutet.
    Vedrök i Västerbotten - mätningar, beräkningar och hälsokonsekvenser2014Report (Other academic)
    Abstract [sv]

    Småskalig vedeldning är en betydande källa till bl a. partiklar, polyaromatiska kolväten (PAH) och sot, föroreningar som påverkar luftkvaliten negativt. Kunskapen är dock begränsad. På uppdrag av Naturvårdsverket har därför detta projekt genomförts, med syfte att förbättra kunskapsläget.Mätningar av vedeldningsrelaterade luftföroreningar har gjorts av IVL i fyra områden med bebyggelse av olika ålder: Vännäs, Vännäsby, Sävar och Taveliden (villaförort i Umeå). En databas för inventerade eldstäder i Västerbotten baserat på information från sotarna har tagits fram av Umeå universitet, som också genomfört frågeundersökning om eldningsvanor. Modellberäkningar av halter och exponering har utförts av SMHI och hälsokonsekvensberäkningar har gjorts av Umeå universitet och SMHI.

  • 239.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Spridning av förbränningsemissioner från småskalig biobränsleeldning - analys av PM2.5 data från Lycksele med hjälp av två Gaussiska spridningsmodeller2002Report (Other academic)
    Abstract [sv]

    Under ca 3 månader vintern 2001/2002 utfördes mätningar av luftkvalitet och meteorologi i Lycksele. En emissionsdatabas (EDB Tot03) för Lycksele har tidigare tagits fram (SLBanalys, 2002). Dessa data utgör grundkomponenter för den spridningsmodellering som här redovisas. Redovisningen begränsas till emissioner av förbränningspartiklar och två lokala spridningsmodeller. Arbetet har utförts med stöd från Energimyndigheten (Projektnummer: P12658-1) och ingår som en del i "Omgivningsklustret" i projektet "Biobränsle Hälsa och Miljö". Detaljerade studier görs i Lycksele och Växjö. Denna rapport redovisar resultat från den spridningsmeteorologiska utvärderingen av mätkampanjen i Lycksele. Arbetet syftar till att utveckla verktyg för kommunal och regional planering, vad avser luftkvalitetsaspekter av biobränsleanvändning.Resultaten av denna undersökning kan sammanfattas på följande sätt: Signifikanta lokala haltbidrag, av förbränningspartiklar från vedeldning, uppmättes huvudsakligen under kalla dagar, då dygnmedeltemperaturen var under –10 grader. Antalet sådana dagar var knappt 30. Modellerna beskriver relativt väl dessa halter. Avvikelsen är störst vid Norrmalm. Under övrig tid var de lokala haltbidragen små. PM2.5 halterna var då i genomsnitt bara ca 2 g/m3 högre än bakgrundshalterna, uppmätta vid Vindeln. Modellerna överskattar då halterna, troligtvis beroende på för höga emissioner orsakat av för hög eldningsaktivitet. Det finns ett starkt samband mellan halter och temperatur. Temperaturberoende korrektionsfunktioner har tagits fram för att beskriva eldningsaktiviteten under mätperioden. Modellerna överensstämmer relativt väl med alla mätdata då eldningsaktiviteten beskrivs med hjälp av dessa funktioner. Emissionsdatabasen (EDB Tot03) överskattar därför troligtvis emissionerna av förbränningspartiklar från småskalig vedeldning. Analysen i denna rapport uppskattar emissionerna under beräkningsperioden till ca 30-50% jämfört med de i emissionsdatabasen. De högsta haltbidragen av förbränningspartiklar från vedeldning i Lycksele inträffar nära utsläppen, inom några 100 meters avstånd från främst närliggande samverkande icke miljögodkända pannor. Kaminernas betydelse för förhöjda halter är osäkra, vilket kommer att utredas i mer detalj när nya emissionsfaktorer erhållits.

  • 240.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Skagerström, M.
    SMHI.
    Vedeldning i småhusområden2003Report (Other academic)
  • 241.
    Omstedt, Gunnar
    et al.
    SMHI, Research Department, Air quality.
    Szegö, Janos
    SMHI.
    Människors exponering för luftföroreningar1990Report (Other academic)
  • 242. Orru, Hans
    et al.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Ebi, Kristie L.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Astrom, Christofer
    Forsberg, Bertil
    Impact of climate change on ozone-related mortality and morbidity in Europe2013In: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 41, no 2, p. 285-294Article in journal (Refereed)
    Abstract [en]

    Ozone is a highly oxidative pollutant formed from precursors in the presence of sunlight, associated with respiratory morbidity and mortality. All else being equal, concentrations of ground-level ozone are expected to increase due to climate change. Ozone-related health impacts under a changing climate are projected using emission scenarios, models and epidemiological data. European ozone concentrations are modelled with the model of atmospheric transport and chemistry (MATCH)-RCA3 (50 x 50 km). Projections from two climate models, ECHAM4 and HadCM3, are applied under greenhouse gas emission scenarios A2 and A1B, respectively. We applied a European-wide exposure-response function to gridded population data and country-specific baseline mortality and morbidity. Comparing the current situation (1990-2009) with the baseline period (1961-1990), the largest increase in ozone-associated mortality and morbidity due to climate change (4-5%) have occurred in Belgium, Ireland, the Netherlands and the UK. Comparing the baseline period and the future periods (2021-2050 and 2041-2060), much larger increases in ozone-related mortality and morbidity are projected for Belgium, France, Spain and Portugal, with the impact being stronger using the climate projection from ECHAM4 (A2). However, in Nordic and Baltic countries the same magnitude of decrease is projected. The current study suggests that projected effects of climate change on ozone concentrations could differentially influence mortality and morbidity across Europe.

  • 243. Orru, Hans
    et al.
    Astrom, Christofer
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Tamm, Tanel
    Ebi, Kristie L.
    Forsberg, Bertil
    Ozone and heat-related mortality in Europe in 2050 significantly affected by changes in climate, population and greenhouse gas emission2019In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, no 7, article id 074013Article in journal (Refereed)
  • 244. Otero, Noelia
    et al.
    Sillmann, Jana
    Mar, Kathleen A.
    Rust, Henning W.
    Solberg, Sverre
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, Bertrand
    Colette, Augustin
    Couvidat, Florian
    Cuvelier, Cournelius
    Tsyro, Svetlana
    Fagerli, Hilde
    Schaap, Martijn
    Manders, Astrid
    Mircea, Mihaela
    Briganti, Gino
    Cappelletti, Andrea
    Adani, Mario
    D'Isidoro, Massimo
    Pay, Maria-Teresa
    Theobald, Mark
    Vivanco, Marta G.
    Wind, Peter
    Ojha, Narendra
    Raffort, Valentin
    Butler, Tim
    A multi-model comparison of meteorological drivers of surface ozone over Europe2018In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 18, no 16, p. 12269-12288Article in journal (Refereed)
  • 245. Ots, Riinu
    et al.
    Young, Dominique E.
    Vieno, Massimo
    Xu, Lu
    Dunmore, Rachel E.
    Allan, James D.
    Coe, Hugh
    Williams, Leah R.
    Herndon, Scott C.
    Ng, Nga L.
    Hamilton, Jacqueline F.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Di Marco, Chiara
    Nemitz, Eiko
    Mackenzie, Ian A.
    Kuenen, Jeroen J. P.
    Green, David C.
    Reis, Stefan
    Heal, Mathew R.
    Simulating secondary organic aerosol from missing diesel-related intermediate-volatility organic compound emissions during the Clean Air for London (ClearfLo) campaign2016In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 16, no 10, p. 6453-6473Article in journal (Refereed)
    Abstract [en]

    We present high-resolution (5aEuro-kmaEuro-aEuro parts per thousand x aEuro-5aEuro-km) atmospheric chemical transport model (ACTM) simulations of the impact of newly estimated traffic-related emissions on secondary organic aerosol (SOA) formation over the UK for 2012. Our simulations include additional diesel-related intermediate-volatility organic compound (IVOC) emissions derived directly from comprehensive field measurements at an urban background site in London during the 2012 Clean Air for London (ClearfLo) campaign. Our IVOC emissions are added proportionally to VOC emissions, as opposed to proportionally to primary organic aerosol (POA) as has been done by previous ACTM studies seeking to simulate the effects of these missing emissions. Modelled concentrations are evaluated against hourly and daily measurements of organic aerosol (OA) components derived from aerosol mass spectrometer (AMS) measurements also made during the ClearfLo campaign at three sites in the London area. According to the model simulations, diesel-related IVOCs can explain on average aEuro parts per thousand aEuro-30aEuro-% of the annual SOA in and around London. Furthermore, the 90th percentile of modelled daily SOA concentrations for the whole year is 3.8aEuro-A mu gaEuro-m(-3), constituting a notable addition to total particulate matter. More measurements of these precursors (currently not included in official emissions inventories) is recommended. During the period of concurrent measurements, SOA concentrations at the Detling rural background location east of London were greater than at the central London location. The model shows that this was caused by an intense pollution plume with a strong gradient of imported SOA passing over the rural location. This demonstrates the value of modelling for supporting the interpretation of measurements taken at different sites or for short durations.

  • 246. Oudin, Anna
    et al.
    Segersson, David
    SMHI, Research Department, Air quality.
    Adolfsson, Rolf
    Forsberg, Bertil
    Association between air pollution from residential wood burning and dementia incidence in a longitudinal study in Northern Sweden2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 6, article id e0198283Article in journal (Refereed)
  • 247. Pechinger, U
    et al.
    Dittmann, E
    Erbes, G
    Johansson, P
    Karppinen, A
    Musson-Genon, L
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Tercier, P
    Intercomparison of methods for parameterizing components of the surface energy balance - a summary of Working Group 1 - COST 710 results2000In: International Journal of Environment and Pollution, ISSN 0957-4352, E-ISSN 1741-5101, Vol. 14, no 1-6, p. 558-564Article in journal (Refereed)
    Abstract [en]

    Working Group 1 of COST Action 710 investigated the use of meteorological pre-processors for short-range dispersion models for regulatory purposes. Two commonly used schemes for estimating boundary-layer fluxes from standard meteorological observations were intercompared using high latitude measurements from Sweden for spring/summer and winter conditions. Ground heat fluxes estimated with five different schemes were compared for data measured in Switzerland. The main results of these studies are presented.

  • 248. Pereira, Susana Cardoso
    et al.
    Marta-Almeida, Martinho
    Carvalho, Ana
    SMHI, Research Department, Air quality.
    Rocha, Alfredo
    Extreme precipitation events under climate change in the Iberian Peninsula2019In: International Journal of Climatology, ISSN 0899-8418, E-ISSN 1097-0088Article in journal (Refereed)
    Abstract [en]

    Precipitation is one of the most important atmospheric variables to assess, particularly in the context of climate change. This study evaluates future changes in precipitation over the Iberian Peninsula (IP) under the RCP8.5 scenario. Changes are assessed for two future climate periods namely (2046-2065) and (2081-2100), relative to a recent reference climate (1986-2005). Here we introduce the concept of precipitation episodes (PEs) and estimate their statistical properties for the present climate and, their changes for future climate scenarios. PEs are defined by considering a full range of durations as well as intensities. This constitutes a novel approach to estimate changes with relevance, for example, for water resources applications. The climate simulations are performed with the Weather Research and Forecast (WRF) model. These are compared with an ensemble of other similar simulations from the Coordinated Downscaling Experiment initiative. This was done to evaluate the performance of the WRF model and also to estimate uncertainty of the derived future projections. Since models may present systematic errors, results from all simulations were previously bias corrected relative to observations using the same quantile mapping method. Under climate change, a great part of the region is expected to experience reduced annual precipitation of approximately 20-40% and reaching 80% in summer by the end of the XXI century. For the PEs, a large reduction in the average number of days and duration of all types of PEs is expected across all seasons and regions. The average intensity of episodes is projected to increase in winter and spring and decrease in summer. These results imply that climate change will likely influence precipitation and precipitation extremes in the 21st century, mostly in southern areas. These, together with projected warming may amplify desertification already taking place in the southern regions of the IP and cause stresses to water resources.

  • 249.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Beräkning av lukt och föroreningshalter i luft runt Neste Polyester i Nol1987Report (Other academic)
  • 250.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Kvaliteten hos nederbördskemiska mätdata som utnyttjas för dataassimilation i "MATCH-Sverige modellen": Rapport till Naturvårdsverkets nationella miljöövervakning, delprogram Luft2002Report (Other academic)
    Abstract [sv]

    MATCH-Sverige modellen utnyttjas bl.a. för kartläggning av den totala föroreningsdepositionen över Sverige, samt för separata studier av Sveriges föroreningsbidrag och den långväga föroreningstransporten. I de beräkningarna ingår en dataassimilation av atmosfärkemiska mätdata i modellen. Det är viktigt att MATCH-Sverige beräkningarna är av god kvalitet, eftersom resultaten ligger till grund för en rad miljöstudier av olika slag i Sverige. Det ställer i sin tur krav på att de atmosfärkemiska mätdata, som utgör indata i dataassimilationen, också är av god kvalitet och att de utnyttjas på rätt sätt. I denna studie redovisas jämförelser och diskuteras osäkerheter av betydelse för dataassimilationen, främst rörande nederbördsmängder samt koncentrationer av svavel-, NOx-kväve och NHx-kväve i nederbörd.I de nationella svenska nederbördskemiska stationsnäten, EMEP och LoN (Luft och Nederbördskemiska stationsnätet) finns två platser, Bredkälen nordost om Östersund och Vavihill i centrala Skåne, med provtagare placerade omedelbart intill varandra vilka kan jämföras dels inbördes, dels med oberoende data från MATCH-Sverige. Jämförelserna mellan EMEP och LoN stationerna, vad gäller uppmätta nederbördsmängder månadsvis, visar relativt dålig samvariation. För år 2000 är samvariationen mellan uppmätta nederbördsmängder i Vavihill t.o.m. mycket dålig. Därmed finns stor risk för att också de uppmätta halterna i nederbörd vid åtminstone en av stationerna är av bristande kvalitet. Görs jämförelser mellan de uppmätta nederbördsmängderna, EMEP och LoN var för sig, och de nederbördsmängder som utnyttjas i MATCH-Sverige och som bygger på SMHI:s hela stationsnät, fås bättre samvariation. Den förklarade variansen som erhålles vid dessa jämförelser är dock avsevärt lägre än vad som fås då närbelägna meteorologiska stationer i SMHI:s stationsnät jämförs.Vid LoN-stationerna (Bredkälen och Vavihill) faller år 2000 ca 70% av sulfat och nitratvärdena inom plus/minus 30% av EMEP-stationens halt men bara ca 25% ammoniumvärdena. De allra flesta av de LoN-halter som faller utanför intervallet är större än 1.3 gånger EMEP-halten. Förhållandena är likartade vid de båda LoN-stationerna. Detta överensstämmer inte med resultaten i Granat (1988), som visade på mycket små skillnader i uppmätta halter mellan "bulk" provtagare (vid LoN-stationerna) och "lock" provtagare (vid EMEP-stationerna). Den bristande överensstämmelsen i nederbördskemiska mätdata mellan stationer som ligger omedelbart intill varandra bör undersökas ytterligare och åtgärder vidtas för att om möjligt förbättra situationen. En sådan åtgärd bör vara att förbättra insamlingen av nederbörd så att uppmätta nederbördsmängder kan erhålls med ungefär samma kvalitet som för rent meteorologiska stationer, även om provtagningsperioderna är längre för de nederbördskemiska stationerna. För är få resultat av god kvalitet från MATCH-Sverige modellen är det betydligt bättre med ett mindre antal atmosfärkemiska mätstationer av hög kvalitet, än ett stort antal stationer med varierande - och okänd - kvalitet. Speciellt viktigt är detta för studier av trender. (Se även Persson m.fl., 1996).

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