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  • 121. Willers, Saskia M.
    et al.
    Eriksson, Charlotta
    Gidhagen, Lars
    SMHI, Forskningsavdelningen, Luftmiljö.
    Nilsson, Mats E.
    Pershagen, Goran
    Bellander, Tom
    Fine and coarse particulate air pollution in relation to respiratory health in Sweden2013Ingår i: European Respiratory Journal, ISSN 0903-1936, E-ISSN 1399-3003, Vol. 42, nr 4, s. 924-934Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Health effects have repeatedly been associated with residential levels of air pollution. However, it is difficult to disentangle effects of long-term exposure to locally generated and long-range transported pollutants, as well as to exhaust emissions and wear particles from road traffic. We aimed to investigate effects of exposure to particulate matter fractions on respiratory health in the Swedish adult population, using an integrated assessment of sources at different geographical scales. The study was based on a nationwide environmental health survey performed in 2007, including 25 851 adults aged 18-80 years. Individual exposure to particulate matter at residential addresses was estimated by dispersion modelling of regional, urban and local sources. Associations between different size fractions or source categories and respiratory outcomes were analysed using multiple logistic regression, adjusting for individual and contextual confounding. Exposure to locally generated wear particles showed associations for blocked nose or hay fever, chest tightness or cough, and restricted activity days with odds ratios of 1.5-2 per 10-mu g.m(-3) increase. Associations were also seen for locally generated combustion particles, which disappeared following adjustment for exposure to wear particles. In conclusion, our data indicate that long-term exposure to locally generated road wear particles increases the risk of respiratory symptoms in adults.

  • 122. Yurkin, Maxim A.
    et al.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Light scattering by a cube: Accuracy limits of the discrete dipole approximation and the T-matrix method2013Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, s. 176-183Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We simulated light-scattering by small and wavelength-sized cubes with three largely different values of the refractive index using the discrete dipole approximation (DDA) and the T-matrix method. Our main goal was to push the accuracy of both methods to the limit. For the DDA we used an earlier developed extrapolation technique based on simulation results for different levels of discretization. For the T-matrix method we developed a procedure to estimate a confidence range for the simulated value, using results for different values of the truncation index (number of multipoles). In most cases this confidence range was reliable, enclosing the corresponding DDA result. We present benchmark results by both methods, including estimated uncertainties, for selected integral and angle-resolved scattering quantities. Estimated relative uncertainties of the DDA result are unprecedentedly small (from 10(-7) to 10(-3)), while relative differences between the T-matrix and DDA results are larger (from 10(-4) to 0.2) in accordance with estimated T-matrix uncertainties. (C) 2012 Elsevier Ltd. All rights reserved.

  • 123.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    The T-matrix code Tsym for homogeneous dielectric particles with finite symmetries2013Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, s. 62-78Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A T-matrix code tailored to non-axisymmetric particles with finite symmetries is described. The code exploits geometric symmetries of particles by use of group theoretical methods. Commutation relations of the T-matrix are implemented for reducing CPU-time requirements. Irreducible representations of finite groups are employed for alleviating ill-conditioning problems in numerical computations. Further, an iterative T-matrix method for particles with small-scale surface perturbations is implemented. The code can compute both differential and integrated optical properties of particles in,either fixed or random orientation. Methods for testing the convergence and correctness of the computational results are discussed. The package also includes a database of pre-computed group-character tables, as well as an interface to the GAP programming language for computational group theory. The code can be downloaded at http://www.rss.chalmers.se/similar to kahnert/Tsym.html. (C) 2013 Elsevier Ltd. All rights reserved.

  • 124. Mackowski, D. W.
    et al.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Mishchenko, M. I.
    A T matrix method based upon scalar basis functions2013Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, s. 113-121Artikel i tidskrift (Refereegranskat)
    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.

  • 125. Mishchenko, Michael I.
    et al.
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Mackowski, Daniel W.
    Wriedt, Thomas
    Peter Waterman and his scientific legacy2013Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 123, s. 1-1Artikel i tidskrift (Övrigt vetenskapligt)
  • 126. Jonsson, Oskar
    et al.
    Andersson, Camilla
    SMHI, Forskningsavdelningen, Luftmiljö.
    Forsberg, Bertil
    Johansson, Christer
    Air pollution episodes in Stockholm regional background air due to sources in Europe and their effects on human population2013Ingår i: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 18, nr 3-4, s. 280-302Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Using air quality measurements, we categorized air pollution according to source sectors in a rural background environment in southern Sweden based on hourly air-mass backward trajectories during 1997-2010. Concentrations of fine (PM2.5) and sum of fine and coarse particulate matter (PM10), accumulation mode particle number, black carbon and surface ozone were 4.0, 3.9, 4.5, 6.8 and 1.3 times higher, respectively, in air masses from the southeast as compared with those in air masses from the cleanest sector in the northwest, consistent with air-mass transport over areas with relatively high emissions of primary particulate matter (PM) and secondary PM precursors. The highest ultrafine particle numbers were associated with clean air from the northwest. We estimate that almost 7.8% and 0.6% higher premature human mortality is caused by PM2.5 and ozone exposure, respectively, when air originates from the southeast as compared with that when air originates from the northwest. Reductions of emissions in eastern Europe would reduce the highest air pollution concentrations and associated health risks. However, since air masses from the southwest are more frequent, emissions in the western part of Europe are more important for annual mean premature mortality.

  • 127. Denby, B. R.
    et al.
    Sundvor, I.
    Johansson, C.
    Pirjola, L.
    Ketzel, M.
    Norman, M.
    Kupiainen, K.
    Gustafsson, M.
    Blomqvist, G.
    Omstedt, Gunnar
    SMHI, Forskningsavdelningen, Luftmiljö.
    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 modelling2013Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 77, s. 283-300Artikel i tidskrift (Refereegranskat)
    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.

  • 128.
    Omstedt, Gunnar
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Andersson, Stefan
    SMHI, Forskningsavdelningen, Luftmiljö.
    Asker, Christian
    SMHI, Affärsverksamhet.
    Jones, Jörgen
    SMHI, Affärsverksamhet.
    Kindell, Sven
    SMHI, Affärsverksamhet.
    Segersson, David
    SMHI, Forskningsavdelningen, Luftmiljö.
    Luftkvalitet i Sverige år 2020: Uppföljning av miljökvalitetsmålet Frisk luft för trafikmiljöer i svenska tätorter2012Rapport (Övrigt vetenskapligt)
    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.

  • 129.
    Omstedt, Gunnar
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Burman, L.
    SLB-analys.
    Beräkningar av kväveoxidhalter vid några gator i Umeå åren 2014 och 2022 med och utan miljözon2012Rapport (Övrigt vetenskapligt)
    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.

  • 130.
    Kahnert, Michael
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Nousiainen, Timo
    Thomas, Manu Anna
    SMHI, Forskningsavdelningen, Luftmiljö.
    Tyynela, Jani
    Light scattering by particles with small-scale surface roughness: Comparison of four classes of model geometries2012Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 113, nr 18, s. 86-97Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We compare four different model geometries for particles with small-scale surface roughness. The geometries are based on regular and stochastic surface perturbations, as well as on 2D- and 3D-roughness models. We further compare T-matrix and discrete dipole computations. Particle size parameters of 5 and 50 are considered, as well as refractive indices of 1.6+0.0005i and 3+0.1i. The effect of small-scale surface roughness on the intensity and polarisation of the scattered light strongly depends on the size parameter and refractive index. In general, 2D surface roughness models predict stronger effects than 3D models. Stochastic surface roughness models tend to predict the strongest depolarising effects, while regular surface roughness models can have a stronger effect on the angular distribution of the scattered intensity. Computations with the discrete dipole approximation only cover a limited range of size parameters. T-matrix computations allow us to significantly extend that range, but at the price of restricting the model particles to symmetric surface perturbations with small amplitudes. (C) 2012 Elsevier Ltd. All rights reserved.

  • 131. Nousiainen, Timo
    et al.
    Zubko, Evgenij
    Lindqvist, Hannakaisa
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Tyynela, Jani
    Comparison of scattering by different nonspherical, wavelength-scale particles2012Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 113, nr 18, s. 121-135Artikel i tidskrift (Refereegranskat)
    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.

  • 132.
    Devasthale, Abhay
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Thomas, Manu Anna
    SMHI, Forskningsavdelningen, Luftmiljö.
    An investigation of statistical link between inversion strength and carbon monoxide over Scandinavia in winter using AIRS data2012Ingår i: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 56, s. 109-114Artikel i tidskrift (Refereegranskat)
    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.

  • 133.
    Kahnert, Michael
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Nousiainen, Timo
    Lindqvist, Hannakaisa
    Ebert, Martin
    Optical properties of light absorbing carbon aggregates mixed with sulfate: assessment of different model geometries for climate forcing calculations2012Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, nr 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Light scattering by light absorbing carbon (LAC) aggregates encapsulated into sulfate shells is computed by use of the discrete dipole method. Computations are performed for a UV, visible, and IR wavelength, different particle sizes, and volume fractions. Reference computations are compared to three classes of simplified model particles that have been proposed for climate modeling purposes. Neither model matches the reference results sufficiently well. Remarkably, more realistic core-shell geometries fall behind homogeneous mixture models. An extended model based on a core-shell-shell geometry is proposed and tested. Good agreement is found for total optical cross sections and the asymmetry parameter. (C) 2012 Optical Society of America

  • 134.
    Devasthale, Abhay
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Tjernstrom, M.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Thomas, Manu Anna
    SMHI, Forskningsavdelningen, Luftmiljö.
    Kahn, B. H.
    Fetzer, E. J.
    Influence of the Arctic Oscillation on the vertical distribution of clouds as observed by the A-Train constellation of satellites2012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 21, s. 10535-10544Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main purpose of this study is to investigate the influence of the Arctic Oscillation (AO), the dominant mode of natural variability over the northerly high latitudes, on the spatial (horizontal and vertical) distribution of clouds in the Arctic. To that end, we use a suite of sensors on-board NASA's A-Train satellites that provide accurate observations of the distribution of clouds along with information on atmospheric thermodynamics. Data from three independent sensors are used (AQUA-AIRS, CALIOP-CALIPSO and CPR-CloudSat) covering two time periods (winter half years, November through March, of 2002-2011 and 2006-2011, respectively) along with data from the ERA-Interim reanalysis. We show that the zonal vertical distribution of cloud fraction anomalies averaged over 67-82 degrees N to a first approximation follows a dipole structure (referred to as "Greenland cloud dipole anomaly", GCDA), such that during the positive phase of the AO, positive and negative cloud anomalies are observed eastwards and westward of Greenland respectively, while the opposite is true for the negative phase of AO. By investigating the concurrent meteorological conditions (temperature, humidity and winds), we show that differences in the meridional energy and moisture transport during the positive and negative phases of the AO and the associated thermodynamics are responsible for the conditions that are conducive for the formation of this dipole structure. All three satellite sensors broadly observe this large-scale GCDA despite differences in their sensitivities, spatio-temporal and vertical resolutions, and the available lengths of data records, indicating the robustness of the results. The present study also provides a compelling case to carry out process-based evaluation of global and regional climate models.

  • 135.
    Bergström, Robert
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    van der Gon, H. A. C. Denier
    Prevot, A. S. H.
    Yttri, K. E.
    Simpson, D.
    Modelling of organic aerosols over Europe (2002-2007) using a volatility basis set (VBS) framework: application of different assumptions regarding the formation of secondary organic aerosol2012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 18, s. 8499-8527Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A new organic aerosol module has been implemented into the EMEP chemical transport model. Four different volatility basis set (VBS) schemes have been tested in long-term simulations for Europe, covering the six years 2002-2007. Different assumptions regarding partitioning of primary organic aerosol and aging of primary semi-volatile and intermediate volatility organic carbon (S/IVOC) species and secondary organic aerosol (SOA) have been explored. Model results are compared to filter measurements, aerosol mass spectrometry (AMS) data and source apportionment studies, as well as to other model studies. The present study indicates that many different sources contribute significantly to organic aerosol in Europe. Biogenic and anthropogenic SOA, residential wood combustion and vegetation fire emissions may all contribute more than 10% each over substantial parts of Europe. This study shows smaller contributions from biogenic SOA to organic aerosol in Europe than earlier work, but relatively greater anthropogenic SOA. Simple VBS based organic aerosol models can give reasonably good results for summer conditions but more observational studies are needed to constrain the VBS parameterisations and to help improve emission inventories. The volatility distribution of primary emissions is one important issue for further work. Emissions of volatile organic compounds from biogenic sources are also highly uncertain and need further validation. We can not reproduce winter levels of organic aerosol in Europe, and there are many indications that the present emission inventories substantially underestimate emissions from residential wood combustion in large parts of Europe.

  • 136. Eriksson, Charlotta
    et al.
    Nilsson, Mats E.
    Willers, Saskia M.
    Gidhagen, Lars
    SMHI, Forskningsavdelningen, Luftmiljö.
    Bellander, Tom
    Pershagen, Goran
    Traffic noise and cardiovascular health in Sweden: The roadside study2012Ingår i: Noise & Health, ISSN 1463-1741, E-ISSN 1998-4030, Vol. 14, nr 59, s. 140-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Long-term exposure to traffic noise has been suggested to increase the risk of cardiovascular diseases (CVD). However, few studies have been performed in the general population and on railway noise. This study aimed to investigate the cardiovascular effects of living near noisy roads and railways. This cross-sectional study comprised 25,851 men and women, aged 18-80 years, who had resided in Sweden for at least 5 years. All subjects participated in a National Environmental Health Survey, performed in 2007, in which they reported on health, annoyance reactions and environmental factors. Questionnaire data on self-reported doctors diagnosis of hypertension and/or CVD were used as outcomes. Exposure was assessed as Traffic Load (millions of vehicle kilometres per year) within 500 m around each participants residential address. For a sub-population (n = 2498), we also assessed road traffic and railway noise in L den at the dwelling facade. Multiple logistic regression models were used to assess Prevalence Odds Ratios (POR) and 95 Confidence Intervals (CI). No statistically significant associations were found between Traffic Load and self-reported hypertension or CVD. In the sub-population, there was no association between road traffic noise and the outcomes; however, an increased risk of CVD was suggested among subjects exposed to railway noise >= 50 dB(A); POR 1.55 (95 CI 1.00-2.40). Neither Traffic Load nor road traffic noise was, in this study, associated with self-reported cardiovascular outcomes. However, there was a borderline-significant association between railway noise and CVD. The lack of association for road traffic may be due to methodological limitations.

  • 137. Haapanala, Paivi
    et al.
    Raisanen, Petri
    Kahnert, Michael
    SMHI, Forskningsavdelningen, Luftmiljö.
    Nousiainen, Timo
    Sensitivity of the shortwave radiative effect of dust on particle shape: Comparison of spheres and spheroids2012Ingår i: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 117, artikel-id D08201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The sensitivity of direct shortwave radiative effects of dust (DRE) to assumed particle shape is investigated. Radiative transfer simulations are conducted using optical properties of either spheres, mass-equivalent spheroids (mass-conserving case), or (mass-equivalent) spheroids whose number concentration is modified so that they have the same midvisible optical thickness (tau(545 nm)) as spheres (tau-conserving case). The impact of particle shape on DRE is investigated for different dust particle effective radii, optical thickness of the dust cloud, solar zenith angle, and spectral surface albedo (ocean, grass, and desert). It is found that the influence of particle shape on the DRE is strongest over ocean. It also depends very strongly on the shape distribution of spheroids used, to a degree that the results for two distributions of spheroids may deviate more from each other than from those for spheres. Finally, the effects of nonsphericity largely depend on whether the mass- or tau-conserving case is considered. For example, when using a shape distribution of spheroids recommended in a recent study for approximating the single-scattering properties of dust, the DRE at the surface differs at most 5% from that from spherical particles in the mass-conserving case. This stems from compensating nonsphericity effects on optical thickness, asymmetry parameter, and single-scattering albedo. However, in the tau-conserving case, the negative DRE at the surface can be up to 15% weaker for spheroids than spheres.

  • 138.
    Langner, Joakim
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    Baklanov, A.
    Christensen, J. H.
    Gauss, M.
    Geels, C.
    Hedegaard, G. B.
    Nuterman, R.
    Simpson, D.
    Soares, J.
    Sofiev, M.
    Wind, P.
    Zakey, A.
    A multi-model study of impacts of climate change on surface ozone in Europe2012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 21, s. 10423-10440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact of climate change on surface ozone over Europe was studied using four offline regional chemistry transport models (CTMs) and one online regional integrated climate-chemistry model (CCM), driven by the same global projection of future climate under the SRES A1B scenario. Anthropogenic emissions of ozone precursors from RCP4.5 for year 2000 were used for simulations of both present and future periods in order to isolate the impact of climate change and to assess the robustness of the results across the different models. The sensitivity of the simulated surface ozone to changes in climate between the periods 20002009 and 2040-2049 differs by a factor of two between the models, but the general pattern of change with an increase in southern Europe is similar across different models. Emissions of isoprene differ substantially between different CTMs ranging from 1.6 to 8.0 Tg yr(-1) for the current climate, partly due to differences in horizontal resolution of meteorological input data. Also the simulated change in total isoprene emissions varies substantially across models explaining part of the different climate response on surface ozone. Ensemble mean changes in summer mean ozone and mean of daily maximum ozone are close to 1 ppb(v) in parts of the land area in southern Europe. Corresponding changes of 95-percentiles of hourly ozone are close to 2 ppb(v) in the same region. In northern Europe ensemble mean for mean and daily maximum show negative changes while there are no negative changes for the higher percentiles indicating that climate impacts on O-3 could be especially important in connection with extreme summer events.

  • 139.
    Langner, Joakim
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    Andersson, Camilla
    SMHI, Forskningsavdelningen, Luftmiljö.
    European summer surface ozone 1990-21002012Ingår i: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, nr 21, s. 10097-10105Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The impact of climate change and changes in ozone precursor emission on summer surface ozone in Europe was studied using a regional CTM over the period 1990 to 2100. Two different climate simulations under the SRES A1B scenario together with ozone precursor emission changes from the RCP4.5 scenario were used as model input. In southern Europe regional climate change leads to increasing surface ozone concentrations during April-September, but projected emission reductions in Europe have a stronger effect, resulting in net reductions of surface ozone concentrations. In northern Europe regional climate change decreases surface O-3 and reduced European emissions acts to further strengthen this trend also when including increasing hemispheric background concentrations. The European O-3 precursor emission reductions in RCP4.5 are substantial and it remains to be seen if these reductions can be achieved. There is substantial decadal variability in the simulations forced by climate variability which is important to consider when looking at changes in surface O-3 concentrations, especially until the first half of the 21st century. In order to account for changes in background O-3 future regional model studies should couple global (hemispheric) and regional CTMs forced by a consistent set of meteorological and precursor emission data.

  • 140.
    Devasthale, Abhay
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Thomas, Manu Anna
    SMHI, Forskningsavdelningen, Luftmiljö.
    Sensitivity of Cloud Liquid Water Content Estimates to the Temperature-Dependent Thermodynamic Phase: A Global Study Using CloudSat Data2012Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 25, nr 20, s. 7297-7307Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The main purpose of this study is to underline the sensitivity of cloud liquid water content (LWC) estimates purely to 1) the shape of computationally simplified temperature-dependent thermodynamic phase and 2) the range of subzero temperatures covered to partition total cloud condensate into liquid and ice fractions. Linear, quadratic, or sigmoid-shaped functions for subfreezing temperatures (down to -20 degrees or -40 degrees C) are often used in climate models and reanalysis datasets for partitioning total condensate. The global vertical profiles of clouds obtained from CloudSat for the 4-yr period June 2006-May 2010 are used for sensitivity analysis and the quantitative estimates of sensitivities based on these realistic cloud profiles are provided. It is found that three cloud regimes in particular-convective clouds in the tropics, low-level clouds in the northern high latitudes, and middle-level clouds over the midlatitudes and Southern Ocean-are most sensitive to assumptions on thermodynamic phase. In these clouds, the LWC estimates based purely on quadratic or sigmoid-shaped functions with a temperature range down to -20 degrees C can differ by up to 20%-40% over the tropics (in seasonal means). 10%-30% over the midlatitudes, and up to 50% over high latitudes compared to a linear assumption. When the temperature range is extended down to -40 degrees C. LWC estimates in the sigmoid case can be much higher than the above values over high-latitude regions compared to the commonly used case with quadratic dependency down to -20 C. This sensitivity study emphasizes the need to critically investigate radiative impacts of cloud thermodynamic phase assumptions in simplified climate models and reanalysis datasets.

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