Change search
Refine search result
45678 301 - 350 of 362
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 301.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    An Eulerian limited-area atmospheric transport model1999In: Journal of applied meteorology (1988), ISSN 0894-8763, E-ISSN 1520-0450, Vol. 38, no 2, p. 190-210Article in journal (Refereed)
    Abstract [en]

    A limited-area, offline, Eulerian atmospheric transport model has been developed. The model is based on a terrain-following vertical coordinate and a mass-conserving, positive definite advection scheme with small phase and amplitude errors. The objective has been to develop a flexible, all purpose offline model. The model includes modules for emission input, vertical turbulent diffusion, and deposition processes. The model can handle an arbitrary number of chemical components and provides a framework for inclusion of modules describing physical and chemical transformation processes between different components. Idealized test cases, as well as simulations of the atmospheric distribution of Rn-222, demonstrate the ability of the model to meet the requirements of mass conservation and positiveness and to produce realistic simulations of a simple atmospheric tracer.

  • 302.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    MATCH - Meso-scale Atmospheric Transport and Chemistry modelling system: Basic transport mode/ description and control experiments with 222Rn1996Report (Other academic)
    Abstract [en]

    A limited area, off-line, Eulerian atmospheric transport model has been developed. The model is based on a terrain following vertical coordinate and a mass conserving, positive definite advection scheme, with small phase and amplitude errors. The objective has been to develop a flexible, all purpose off- line model. The model includes modules for emission input, vertical turbulent diffusion and deposition processes. The model can handle an arbitrary number of chemical components and provides a framework for inclusion of modules describing physical and chemical transformation processes between different components. Idealized test cases as well as simulation of the atmospheric distribution of 222Rn demonstrates the ability of the model to meet the requirements of mass conservation and positiveness and to produce realistic simulations of a simple atmospheric tracer.

    Download full text (pdf)
    fulltext
  • 303.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    ATTEMPTS TO APPLY 4-DIMENSIONAL DATA ASSIMILATION OF RADIOLOGICAL DATA USING THE ADJOINT TECHNIQUE1993In: Radiation Protection Dosimetry, ISSN 0144-8420, E-ISSN 1742-3406, Vol. 50, no 2-4, p. 333-337Article in journal (Refereed)
    Abstract [en]

    A data assimilation procedure is presented. By feeding measurements into a dispersion model. using the adjoint technique, it is shown that the proper transport level as well as the source intensity can he found. The technique is tested on a fictitious accidental release. and thus fictitious measurements are used.

  • 304.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar för bromcyan2009Report (Other academic)
  • 305.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Rodhe, H
    Granat, L
    Modelling of sulfur deposition in the southern Asian region1995In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 85, no 4, p. 2337-2343Article in journal (Refereed)
    Abstract [en]

    Acidification problems in developing countries are expected to become more prevalent in the coming decades. Assessments of means of abatement strategies are likely to become of vital interest. This paper presents some preliminary results of modelling of acidic deposition due to anthropogenic emissions of sulfur in the Southern Asian region. It is concluded that the study has some shortcomings, that has to be addressed in future work, such as lack of treatment of deep convection and that deposition and transformation rates used are not adapted to the tropics. Only very limited validation has been possible due to the lack of relevant measurements. Wet deposition data from rural Thailand are in fair agreement with calculated values. The study is one part of a larger project encompassing mapping ecosystem sensitivity to acid deposition, wet chemistry measurements and atmospheric transfer modelling.

  • 306. Rodhe, H
    et al.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Gallardo, L
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Global scale transport of acidifying pollutants1995In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 85, no 1, p. 37-50Article in journal (Refereed)
    Abstract [en]

    During the past few years several attempts have been made to use three-dimensional tracer transport models to simulate the global distribution of sulfur and nitrogen compounds from both natural and anthropogenic sources. We review these studies and show examples of estimated distributions of the total deposition of sulfur, oxidized nitrogen and ammonium as well as the pH of precipitation. The simulated patterns are compared with observations. Weaknesses in these estimates resulting from lack of knowledge of emissions, chemical transformations and removal processes are emphasized and discussed. We also show examples of how the models can be used to estimate past and future deposition patterns. In particular, we use the IPCC scenario IS92a to estimate the possible sulfur deposition around the world in the year 2050. A comparison with critical load values for sulfur deposition indicates that substantial parts of South and East Asia are at risk for acidification problems in the future.

  • 307.
    Rummukainen, Markku
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Johansson, Daniel J.A.
    Institutionen för energi och miljö, avdelningen för fysisk resursteori, Chalmers.
    Azar, Christian
    Institutionen för energi och miljö, avdelningen för fysisk resursteori, Chalmers.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Smith, Henrik
    Centrum för miljö och klimatforskning, Lunds universitet.
    Uppdatering av den vetenskapliga grunden för klimatarbetet2011Report (Other academic)
    Abstract [sv]

    Det naturvetenskapliga kunskapsläget om klimatförändringarna förbättrats ständigt genom forskningen om klimatsystemet, klimatpåverkan, klimatets variationer och förändringar samt klimateffekter. Kunskapsläget är väletablerat när det gäller den grundläggande fysiken bakom växthuseffekten, liksom att genomsnittstemperaturen vid jordytan stigit de senaste femtio åren. Det är också mycket sannolikt att det mesta av den observerade uppvärmningen beror på mänsklig klimatpåverkan. Samtidigt finns det betydande osäkerheter när det gäller konsekvenserna av klimatförändringarna samt hur mycket utsläppen behöver minska för att man ska nå ett givet klimatmål. Värdet på klimatkänsligheten är den viktigaste faktorn för beräkningar av hur mycket växthusgaser vi kan släppa ut, givet ett visst temperaturmål. Forskningen visar att det behövs stora och snabba utsläppsminskningar för att uppnå tvågradersmålet. För att nå ett lägre temperaturmål, till exempel ett 1,5-gradersmål, är de nödvändiga utsläppsminskningarna än mer omfattande.  För att nå tvågradersmålet med en sannolikhet runt 70 % krävs uppskattningsvis att de globala växthusgasutsläppen minskar i storleksordningen 50‒60 % från år 2000 till 2050, och minskar med nära 100 % till 2100.  För att nå ett 1,5-gradersmål med en sannolikhet runt 70 % krävs globala nollutsläpp redan runt år 2050.  För att nå ett 1,5-gradersmål med en sannolikhet runt 50 % krävs uppskattningsvis att de globala växthusgasutsläppen minskar i storleksordningen 80 % från år 2000 till 2050, och med nära 100 % till 2100. Det är framför allt de kumulativa utsläppen av koldioxid och andra långlivade växthusgaser som räknas när det gäller hur stora klimatförändringarna blir bortom 2100. Ju senare de globala utsläppen kulminerar, och ju högre nivå de då är på, desto större blir utmaningen för att åstadkomma en tillräckligt snabb påföljande utsläppsminskningstakt. Reducerade utsläpp av kortlivade klimatpåverkande ämnen är viktigt främst i ett kortare perspektiv. Det finns olika modeller för hur de globala utsläppsminskningarna kan fördelas mellan olika regioner och länder. Dessa baseras inte på naturvetenskapliga principer utan är beroende av politiska och andra ställningstaganden. För en del länder skiljer sig resultaten mycket beroende på valet av fördelningsmodell. För de flesta industriländer är slutsatsen dock generellt sett densamma: jämfört med idag behöver deras utsläpp minska mycket kraftigt.  För att nå tvågradersmålet med i storleksordningen 70 % sannolikhet krävs, givet en globalt lika per capita fördelning av utsläppen från och med 2050, att utsläppen i Sverige minskar med cirka 70 % från år 2005 till 2050. Den motsvarande siffran för EU är cirka 80 %.  För att nå ett 1,5-gradersmål med i storleksordningen 70 % sannolikhet krävs, givet en globalt lika per capita fördelning av utsläppen från och med 2050, att utsläppen minskar från år 2005 till år 2050 med runt 100 % i Sverige och i EU, och i andra länder.  För att nå ett 1,5-gradersmål med i storleksordningen 50 % sannolikhet krävs, givet en globalt lika per capita fördelning av utsläppen från och med 2050, att utsläppen i Sverige och EU minskar med drygt 90 % från år 2005 till 2050. Nettoutsläpp av koldioxid från avskogning och utrikes luft- och sjöfart ingår inte i dessa uppskattningar. Generellt blir riskerna för allvarliga klimateffekter mindre ju mer ambitiöst temperaturmål som väljs, men riskerna försvinner inte med tvågradersmålet, och inte ens med ett 1,5-gradersmål. Jämfört med IPCC:s AR4 från 2007, har nya forskningsresultat publicerats om klimateffekter. I denna rapport har vi fokuserat på havsnivåhöjningen, havsförsurningen, den biologiska mångfalden samt klimateffekter i Arktis. Jämfört med genomgången av kunskapsläget i AR4 visar nya resultat att den framtida havsnivåhöjningen kan bli större, havsförsurningens effekter på marina ekosystem omfattande och även om en del arter kan vara anpassningsbara, kan världens ekosystem påverkas av skillnader i olika arters sårbarhet för klimatförändringarna. I Arktis sker snabba förändringar. Sammantaget ter sig riskerna för allvarliga klimateffekter större jämfört med AR4. Denna rapport utgår från naturvetenskaplig klimatforskning sedan 2007. Rapporten förordar inte något specifikt temperaturmål, någon specifik utsläppsbana eller specifika policybeslut. Dessa är föremål för politiska avgöranden.

    Download full text (pdf)
    FULLTEXT01
  • 308. Saaroni, H.
    et al.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Hiemstra, J. A.
    Pearlmutter, D.
    Urban Green Infrastructure as a tool for urban heat mitigation: Survey of research methodologies and findings across different climatic regions2018In: Urban Climate, ISSN 2212-0955, E-ISSN 2212-0955, Vol. 24, p. 94-110Article in journal (Refereed)
  • 309. Samson, Roeland
    et al.
    Moretti, Marco
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Branquinho, Cristina
    Fares, Silvano
    Morelli, Federico
    Niinemets, Ülo
    Paolett, Elena
    Pinho, Pedro
    Sgrigna, Gregorio
    Stojanovski, Vladimir
    Tiwary, Abhishek
    Sicard, Pierre
    Calfapietra, Carlo
    Towards an integrative approach to evaluate the environmental ecosystem services provided by urban forest2019In: Journal of Forestry Research, ISSN 1007-662X, E-ISSN 1993-0607, p. 1-16Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 310. Sand, M.
    et al.
    Berntsen, T. K.
    von Salzen, K.
    Flanner, M. G.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Victor, D. G.
    Response of Arctic temperature to changes in emissions of short-lived climate forcers2016In: Nature Climate Change, ISSN 1758-678X, E-ISSN 1758-6798, Vol. 6, no 3, p. 286-+Article in journal (Refereed)
    Abstract [en]

    There is growing scientific(1,2) and political(3,4) interest in the impacts of climate change and anthropogenic emissions on the Arctic. Over recent decades temperatures in the Arctic have increased at twice the global rate, largely as a result of ice-albedo and temperature feedbacks(5-8). Although deep cuts in global CO2 emissions are required to slow this warming, there is also growing interest in the potential for reducing short-lived climate forcers (SLCFs; refs 9,10). Politically, action on SLCFs may be particularly promising because the benefits of mitigation are seen more quickly than for mitigation of CO2 and there are large co-benefits in terms of improved air quality(11). This Letter is one of the first to systematically quantify the Arctic climate impact of regional SLCFs emissions, taking into account black carbon (BC), sulphur dioxide (SO2), nitrogen oxides (NOx), volatile organic compounds (VOCs), organic carbon (OC) and tropospheric ozone (O-3), and their transport processes and transformations in the atmosphere. This study extends the scope of previous works(2,12) by including more detailed calculations of Arctic radiative forcing and quantifying the Arctic temperature response. We find that the largest Arctic warming source is from emissions within the Asian nations owing to the large absolute amount of emissions. However, the Arctic is most sensitive, per unit mass emitted, to SLCFs emissions from a small number of activities within the Arctic nations themselves. Astringent, but technically feasible mitigation scenario for SLCFs, phased in from 2015 to 2030, could cut warming by 0.2 (+/- 0.17) K in 2050.

  • 311. Schmidt, Karsten
    et al.
    Yurkin, Maxim A.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    A case study on the reciprocity in light scattering computations2012In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 20, no 21, p. 23253-23274Article in journal (Refereed)
    Abstract [en]

    The fulfillment of the reciprocity by five publicly available scattering programs is investigated for a number of different particles. Reciprocity means that the source and the observation point of a given scattering configuration can be interchanged without changing the result. The programs under consideration are either implementations of T-matrix methods or of the discrete dipole approximation. Similarities and differences concerning their reciprocity behavior are discussed. In particular, it is investigated whether and under which conditions reciprocity tests can be used to evaluate the scattering results obtained by the different programs for the given particles. (c) 2012 Optical Society of America

  • 312.
    Segersson, David
    SMHI, Research Department, Air quality.
    A dynamic model for shipping emissions: Adaptation of Airviro and application in the Baltic Sea2014Report (Other academic)
    Abstract [en]

    In many countries, shipping is an important contributor to emissions of air pollutants. For sulphur, shipping is nowadays often considered the most important source of emissions. Shipping also emits significant amounts of nitric oxides, particles and volatile organic compounds. From a climate change perspective, shipping is an important source of green house gases, and also contributes significantly to emissions of short lived climate pollutants, such as soot. Emissions to air from shipping have impact on air quality, climate change and acidification. To understand the impact of shipping emissions on the environment, human health and the climate, it is necessary to quantify, map and describe the emissions. Due to lack of data and knowledge, estimates of emissions from shipping have always been very uncertain. One reason to the uncertainties has been difficulties to locate the large number of ships travelling at sea, another reason has been uncertainties regarding emission factors. Since year 2007 AIS (Automatic Identification System) has been a standard for positioning and identification of ships at sea. AIS is complementary to radar and describes location, speed and identity of ships with high precision. This development creates new possibilities to improve information regarding emissions. A system that makes use of data from AIS to estimate emissions from shipping has been developed. The system allows emissions to be calculated for shipping based on the latest knowledge regarding emission factors and makes use of ship specific data as far as possible. The general motivation is to improve the quality of estimations of emissions of air pollutants, green house gases and SLCP (Short Lived Climate Pollutants) as well as to provide a flexible tool to be used for related questions. The system is an integrated part of the Air Quality Management system Airviro. The developed system has been applied for the Baltic Sea. This application of the system is called Shipair. Shipair contains AIS information for the whole Baltic Sea, and the North Sea up to the southern coast of Norway. The AIS information comes from the international AIS database operated by HELCOM. Besides AIS, the Shipair application also makes use of a web service operated by Swedish Maritime Administration to acquire and estimate ship specific parameters needed for emission calculations. The Shipair application of Airviro has been validated by comparing calculated and measured fuel consumption for a small number of ships. The differences between measured and calculated fuel consumption are below 10 % for the individual ships, which is considered well within what could be expected. Comparisons have also been made with results from other ship emission inventories. The results are similar to those of the STEAM2 model published by FMI (Finnish Meteorological Institute), which are based on a similar methodology. Emissions used by from EMEP (Environmental Monitoring and Evaluation Programme) on the other hand can be seen to give significantly higher emissions than both Shipair and STEAM2. Finally, indirect verification has been made by comparing results from dispersion models with concentrations measured in ambient air. Due to a large number of other emission sources that dominate the concentrations in ambient air, these results can confirm that the Shipair calculations are reasonable, but does not provide any closer evaluation of the quality of the results. To investigate if estimates based on fuel statistics, currently used in international reporting of Swedish shipping emissions, are reasonable, a comparison has also been made with estimations based on national fuel statistics. The results indicate that estimations based on the fuel statistics could be underestimating the emissions of CO2 from domestic shipping with approximately 50 %.

    Download full text (pdf)
    FULLTEXT01
  • 313.
    Segersson, David
    SMHI, Research Department, Air quality.
    Numerical Quantification of Driving Rain on Buildings2003Report (Other academic)
    Abstract [en]

    Rain, which is given a horizontal velocity component by the influence of wind, is termed winddriven or driving rain. Driving rain is one of the main sources to the amount of moisture a building is exposed to, and thereby contributes to the processes deteriorating the building envelope. Examples of damages to the building envelope that the onslaught of driving rain directly or indirectly can contribute to are: cracks caused by the freezing of water absorbed in the facade, mould or rot, corrosion of concrete reinforcements and soiling patterns. Knowledge about the exposure of a building to driving rain is needed in order to minimise the deteriorating processes, and thus contributes to ensure a satisfactory performance of the building design.

    This work is meant as an introduction to the field of numerical quantification of driving rain on buildings. Focus is set on three-dimensional simulation of the wind flow and raindrop trajectories using CFD (Computational Fluid Dynamics). lnterest is also paid to some specific properties of rainfall, such as drop size distributions and drag forces on raindrops. The study includes a detailed description of a method to calculate the driving rain distribution on a building, as well as application of the method to a rectangular facade. A qualitative evaluation of the results indicates that the method can be used to calculate the mean distribution of driving rain on simple geometries with sufficient accuracy.

    Download full text (pdf)
    fulltext
  • 314.
    Segersson, David
    et al.
    SMHI, Research Department, Air quality.
    Eneroth, Kristina
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Johansson, Christer
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Nylen, Anders Engstrom
    Forsberg, Bertil
    Health Impact of PM10, PM2.5 and Black Carbon Exposure Due to Different Source Sectors in Stockholm, Gothenburg and Umea, Sweden2017In: International Journal of Environmental Research and Public Health, ISSN 1661-7827, E-ISSN 1660-4601, Vol. 14, no 7, article id 742Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 315. Silva, F. C.
    et al.
    Borrego, C.
    Keizer, J. J.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Verheijen, F. G. A.
    Effects of moisture content on wind erosion thresholds of biochar2015In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 123, p. 121-128Article in journal (Refereed)
    Abstract [en]

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

  • 316. Silver, Jeremy D.
    et al.
    Christensen, Jesper H.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rayner, Peter J.
    Brandt, Jorgen
    Multi-species chemical data assimilation with the Danish Eulerian hemispheric model: system description and verification2016In: Journal of Atmospheric Chemistry, ISSN 0167-7764, E-ISSN 1573-0662, Vol. 73, no 3, p. 261-302Article in journal (Refereed)
  • 317. Simpson, D.
    et al.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Christensen, J. H.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Geels, C.
    Nyiri, A.
    Posch, M.
    Soares, J.
    Sofiev, M.
    Wind, P.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Impacts of climate and emission changes on nitrogen deposition in Europe: a multi-model study2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 13, p. 6995-7017Article in journal (Refereed)
    Abstract [en]

    The impact of climate and emissions changes on the deposition of reactive nitrogen (Nr) over Europe was studied using four offline regional chemistry transport models (CTMs) driven by the same global projection of future climate over the period 2000-2050. Anthropogenic emissions for the years 2005 and 2050 were used for simulations of both present and future periods in order to isolate the impact of climate change, hemispheric boundary conditions and emissions, and to assess the robustness of the results across the different models. The results from these four CTMs clearly show that the main driver of future N-deposition changes is the specified emission change. Under the specified emission scenario for 2050, emissions of oxidised nitrogen were reduced substantially, whereas emissions of NH3 increase to some extent, and these changes are largely reflected in the modelled concentrations and depositions. The lack of sulfur and oxidised nitrogen in the future atmosphere results in a much larger fraction of NHx being present in the form of gaseous ammonia. Predictions for wet and total deposition were broadly consistent, although the three fine-scale models resolve European emission areas and changes better than the hemisphericscale model. The biggest difference in the models is for predictions of individual N compounds. One model (EMEP) was used to explore changes in critical loads, also in conjunction with speculative climate-induced increases in NH3 emissions. These calculations suggest that the area of ecosystems that exceeds critical loads is reduced from 64% for year 2005 emissions levels to 50% for currently estimated 2050 levels. A possible climate-induced increase in NH3 emissions could worsen the situation, with areas exceeded increasing again to 57% (for a 30% NH3 emission increase).

    Download full text (pdf)
    fulltext
  • 318. Simpson, D.
    et al.
    Benedictow, A.
    Berge, H.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Emberson, L. D.
    Fagerli, H.
    Flechard, C. R.
    Hayman, G. D.
    Gauss, M.
    Jonson, J. E.
    Jenkin, M. E.
    Nyiri, A.
    Richter, C.
    Semeena, V. S.
    Tsyro, S.
    Tuovinen, J-P
    Valdebenito, A.
    Wind, P.
    The EMEP MSC-W chemical transport model - technical description2012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 16, p. 7825-7865Article in journal (Refereed)
    Abstract [en]

    The Meteorological Synthesizing Centre-West (MSC-W) of the European Monitoring and Evaluation Programme (EMEP) has been performing model calculations in support of the Convention on Long Range Transboundary Air Pollution (CLRTAP) for more than 30 years. The EMEP MSC-W chemical transport model is still one of the key tools within European air pollution policy assessments. Traditionally, the model has covered all of Europe with a resolution of about 50 km x 50 km, and extending vertically from ground level to the tropopause (100 hPa). The model has changed extensively over the last ten years, however, with flexible processing of chemical schemes, meteorological inputs, and with nesting capability: the code is now applied on scales ranging from local (ca. 5 km grid size) to global (with 1 degree resolution). The model is used to simulate photo-oxidants and both inorganic and organic aerosols. In 2008 the EMEP model was released for the first time as public domain code, along with all required input data for model runs for one year. The second release of the EMEP MSC-W model became available in mid 2011, and a new release is targeted for summer 2012. This publication is in-tended to document this third release of the EMEP MSC-W model. The model formulations are given, along with details of input data-sets which are used, and a brief background on some of the choices made in the formulation is presented. The model code itself is available at www.emep.int, along with the data required to run for a full year over Europe.

    Download full text (pdf)
    fulltext
  • 319. Simpson, David
    et al.
    Bartnicki, Jerzy
    Jalkanen, Jukka-Pekka
    Hansson, Hans-Christen
    Hertel, Ole
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Pryor, Sara C.
    Environmental Impacts-Atmospheric Chemistry2015Chapter in book (Other academic)
    Abstract [en]

    This chapter addresses sources and trends of atmospheric pollutants and deposition in relation to the Baltic Sea region. Air pollution is shown to have important effects, including significant contributions to nitrogen loading of the Baltic Sea area, ecosystem impacts due to acidifying and eutrophying pollutants and ozone, and human health impacts. Compounds such as sulphate and ozone also have climate impacts. Emission changes have been very significant over the past 100 years, although very different for land-and sea-based sources. Land-based emissions generally peaked around 1980-1990 and have since reduced due to emissions control measures. Emissions from shipping have been steadily increasing for decades, but recent measures have reduced sulphur and particulate emissions. Future developments depend strongly on policy developments. Changes in concentration and deposition of the acidifying components generally follow emission changes within the European area. Mean ozone levels roughly doubled during the twentieth century across the northern hemisphere, but peak levels have reduced in many regions in the past 20 years. The main changes in air pollution in the Baltic Sea region are due to changes in emissions rather than to climate change.

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

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

  • 321. SJODIN, A
    et al.
    LOMAN, G
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    LONG-TERM CONTINUOUS MEASUREMENTS OF AIR POLLUTANT CONCENTRATIONS, METEOROLOGY AND TRAFFIC ON A RURAL MOTORWAY AND A MODEL VALIDATION1994In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 147, p. 365-375Article in journal (Refereed)
    Abstract [en]

    Air concentrations of carbon monoxide (CO), nitrogen oxide (NO) and nitrogen dioxide (NO2) were continuously monitored at a rural motorway site in Sweden for the period February-December 1990. In addition, local meteorology and traffic parameters were measured in order to validate a dispersion model. Even close to the motorway, the concentrations of CO and NO2 were well below Swedish air quality guidelines. For long-term averages the regional background contributed significantly to the downwind levels. The atmospheric reaction between primary emitted NO and background ozone (O3) tends to be a major source of downwind NO2, also fairly close to the road (10 m from the road shoulder), where the average NO2/NO(x) ratio was approximately 0.4. The validated model employs a percentile analysis on the basis of the HIWAY-2 and CALINE4 models and a separate emission model. The agreement between measured and modelled data, as refered to the 98th percentile, was good for NO2 but moderate for CO. This is probably partly caused by uncertainties in emission factors for CO for heavy vehicles. Since a good agreement was observed between measured and calculated NO(x) concentrations, problems in adequately modelling NO2 are probably associated with uncertainties as to NO2/NO(x) ratios in the exhaust, or the modelling of the O3 reaction.

  • 322. Soares, Joana
    et al.
    Sofiev, Mikhail
    Geels, Camilla
    Christensen, Jens H.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Tsyro, Svetlana
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Impact of climate change on the production and transport of sea salt aerosol on European seas2016In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 16, no 20, p. 13081-13104Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 323. Sofiev, M.
    et al.
    Berger, U.
    Prank, M.
    Vira, J.
    Arteta, J.
    Belmonte, J.
    Bergmann, K. -C
    Cheroux, F.
    Elbern, H.
    Friese, E.
    Galan, C.
    Gehrig, R.
    Khvorostyanov, D.
    Kranenburg, R.
    Kumar, U.
    Marecal, V.
    Meleux, F.
    Menut, L.
    Pessi, A. -M
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Ritenberga, O.
    Rodinkova, V.
    Saarto, A.
    Segers, A.
    Severova, E.
    Sauliene, I.
    Siljamo, P.
    Steensen, B. M.
    Teinemaa, E.
    Thibaudon, M.
    Peuch, V. -H
    MACC regional multi-model ensemble simulations of birch pollen dispersion in Europe2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 14, p. 8115-8130Article in journal (Refereed)
    Abstract [en]

    This paper presents the first ensemble modelling experiment in relation to birch pollen in Europe. The seven-model European ensemble of MACC-ENS, tested in trial simulations over the flowering season of 2010, was run through the flowering season of 2013. The simulations have been compared with observations in 11 countries, all members of the European Aeroallergen Network, for both individual models and the ensemble mean and median. It is shown that the models successfully reproduced the timing of the very late season of 2013, generally within a couple of days from the observed start of the season. The end of the season was generally predicted later than observed, by 5 days or more, which is a known feature of the source term used in the study. Absolute pollen concentrations during the season were somewhat underestimated in the southern part of the birch habitat. In the northern part of Europe, a record-low pollen season was strongly overestimated by all models. The median of the multi-model ensemble demonstrated robust performance, successfully eliminating the impact of outliers, which was particularly useful since for most models this was the first experience of pollen forecasting.

    Download full text (pdf)
    fulltext
  • 324. Sofiev, Mikhail
    et al.
    Ritenberga, Olga
    Albertini, Roberto
    Arteta, Joaquim
    Belmonte, Jordina
    Bernstein, Carmi Geller
    Bonini, Maira
    Celenk, Sevcan
    Damialis, Athanasios
    Douros, John
    Elbern, Hendrik
    Friese, Elmar
    Galan, Carmen
    Oliver, Gilles
    Hrga, Ivana
    Kouznetsov, Rostislav
    Krajsek, Kai
    Magyar, Donat
    Parmentier, Jonathan
    Plu, Matthieu
    Prank, Marje
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Steensen, Birthe Marie
    Thibaudon, Michel
    Segers, Arjo
    Stepanovich, Barbara
    Valdebenito, Alvaro M.
    Vira, Julius
    Vokou, Despoina
    Multi-model ensemble simulations of olive pollen distribution in Europe in 2014: current status and outlook2017In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 20, p. 12341-12360Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 325. Solberg, S
    et al.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Laurila, T
    Lindskog, A
    Changes in Nordic surface ozone episodes due to European emission reductions in the 1990s2005In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 39, no 1, p. 179-192Article in journal (Refereed)
    Abstract [en]

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

  • 326. Solberg, S
    et al.
    Derwent, R G
    Hov, O
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Lindskog, A
    European abatement of surface ozone in a global perspective2005In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 34, no 1, p. 47-53Article in journal (Refereed)
    Abstract [en]

    EU's programme Clean Air for Europe (CAFE) is presently revising the policy on air quality which will lead to the adoption of a thematic strategy on air pollution under the Sixth Environmental Action Programme by mid-2005. For the abatement of surface ozone it is becoming evident that processes outside European control will be crucial for meeting long-term aims and air quality guidelines in Europe in the future. Measurements and modelling results indicate that there is a strong link between climate change and surface ozone. A warmer and dryer European climate is very likely to lead to increased ozone concentrations. Furthermore, increased anthropogenic emissions in developing economies in Asia are likely to raise the hemispheric background level of ozone. A significant increase in the background concentration of ozone has been observed at several sites in Northern Europe although the underlying causes are not settled. The photochemical formation of tropospheric ozone from increased concentrations of methane and CO may also lead to a higher ozone level on a global scale. Gradually, these effects may outweigh the effect of the reduced European ozone precursor emissions. This calls for a global or hemispheric perspective in the revision of the European air quality policy for ozone.

  • 327. Stockfelt, Leo
    et al.
    Andersson, Eva M.
    Molnar, Peter
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Segersson, David
    SMHI, Research Department, Air quality.
    Rosengren, Annika
    Barregard, Lars
    Sallsten, Gerd
    Long-term effects of total and source-specific particulate air pollution on incident cardiovascular disease in Gothenburg, Sweden2017In: Environmental Research, ISSN 0013-9351, E-ISSN 1096-0953, Vol. 158, p. 61-71Article in journal (Refereed)
  • 328. Sun, Bingqiang
    et al.
    Bi, Lei
    Ping, Yang
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Kattawar, George
    nvariant Imbedding T-matrix Method for Light Scattering by Nonspherical and Inhomogeneous Particles2019 (ed. 1st)Book (Refereed)
  • 329. Sun, Bingqiang
    et al.
    Bi, Lei
    Yang, Ping
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Kattawar, George
    View on ScienceDirectInvariant Imbedding T-matrix Method for Light Scattering by Nonspherical and Inhomogeneous Particles2019 (ed. 1)Book (Refereed)
  • 330.
    Taesler, Roger
    et al.
    SMHI, Research Department.
    Andersson, C.
    SMHI.
    Wallentin, C.
    SMHI.
    Krieg, Roland
    SMHI, Research Department, Air quality.
    Klimatkorrigering för energiförbrukningen i ett eluppvärmt villaområde1987Report (Other academic)
  • 331. Takano, Y.
    et al.
    Liou, K. N.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Yang, P.
    The single-scattering properties of black carbon aggregates determined from the geometric-optics surface-wave approach and the T-matrix method2013In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 125, p. 51-56Article in journal (Refereed)
    Abstract [en]

    The single-scattering properties of eight black carbon (BC, soot) fractal aggregates, composed of primary spheres from 7 to 600, computed by the geometric-optics surface-wave (GOS) approach coupled with the Rayleigh-Gans-Debye (RGD) adjustment for size parameters smaller than approximately 2, are compared with those determined from the superposition T-matrix method. We show that under the condition of random orientation, the results from GOS/RGD are in general agreement with those from T-matrix in terms of the extinction and absorption cross-sections, the single-scattering co-albedo, and the asymmetry factor. When compared with the specific absorption (m(2)/g) measured in the laboratory, we illustrate that using the observed radii of primary spheres ranging from 3.3 to 25 nm, the theoretical values determined from GOS/RGD for primary sphere numbers of 100-600 are within the range of measured values. The GOS approach can be effectively applied to aggregates composed of a large number of primary spheres (e.g., > 6000) and large size parameters (>> 2) in terms of computational efforts. (C) 2013 Elsevier Ltd. All rights reserved.

  • 332. Teixeira, J. C.
    et al.
    Fallmann, J.
    Carvalho, Ana
    SMHI, Research Department, Air quality.
    Rocha, A.
    Surface to boundary layer coupling in the urban area of Lisbon comparing different urban canopy models in WRF2019In: Urban Climate, ISSN 2212-0955, E-ISSN 2212-0955, Vol. 28, article id UNSP 100454Article in journal (Refereed)
  • 333. Theobald, Mark R.
    et al.
    Vivanco, Marta G.
    Aas, Wenche
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Ciarelli, Giancarlo
    Couvidat, Florian
    Cuvelier, Kees
    Manders, Astrid
    Mircea, Mihaela
    Pay, Maria-Teresa
    Tsyro, Svetlana
    Adani, Mario
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, Bertrand
    Briganti, Gino
    Cappelletti, Andrea
    D'Isidoro, Massimo
    Fagerli, Hilde
    Mar, Kathleen
    Otero, Noelia
    Raffort, Valentin
    Roustan, Yelva
    Schaap, Martijn
    Wind, Peter
    Colette, Augustin
    An evaluation of European nitrogen and sulfur wet deposition and their trends estimated by six chemistry transport models for the period 1990-20102019In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 19, no 1, p. 379-405Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 334.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Sensitivity of free tropospheric carbon monoxide to atmospheric weather states and their persistency: an observational assessment over the Nordic countries2014In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 14, no 21, p. 11545-11555Article in journal (Refereed)
    Abstract [en]

    Among various factors that influence the long-range transport of pollutants in the free troposphere (FT), the prevailing atmospheric weather states probably play the most important role in governing characteristics and efficacy of such transport. The weather states, such as a particular wind pattern, cyclonic or anticyclonic conditions, and their degree of persistency determine the spatio-temporal distribution and the final fate of the pollutants. This is especially true in the case of Nordic countries, where baroclinic disturbances and associated weather fronts primarily regulate local meteorology, in contrast to the lower latitudes where a convective paradigm plays a similarly important role. Furthermore, the long-range transport of pollutants in the FT has significant contribution to the total column burden over the Nordic countries. However, there is insufficient knowledge on the large-scale co-variability of pollutants in the FT and atmospheric weather states based solely on observational data over this region. The present study attempts to quantify and understand this statistical co-variability while providing relevant meteorological background. To that end, we select eight weather states that predominantly occur over the Nordic countries and three periods of their persistency (3 days, 5 days, and 7 days), thus providing in total 24 cases to investigate sensitivity of free tropospheric carbon monoxide, an ideal tracer for studying pollutant transport, to these selected weather states. The eight states include four dominant wind directions (namely, NW, NE, SE and SW), cyclonic and anticyclonic conditions, and the enhanced positive and negative phases of the North Atlantic Oscillation (NAO). For our sensitivity analysis, we use recently released Version 6 retrievals of CO at 500 hPa from the Atmospheric Infrared Sounder (AIRS) onboard Aqua satellite covering the 11-year period from September 2002 through August 2013 and winds from the ECMWF's ERA-Interim project to classify weather states for the same 11-year period. We show that, among the various weather states studied here, southeasterly winds lead to highest observed CO anomalies (up to +8%) over the Nordic countries while transporting pollution from the central and eastern parts of Europe. The second (up to +4%) and third highest (up to +2.5%) CO anomalies are observed when winds are northwesterly (facilitating inter-continental transport from polluted North American regions) and during the enhanced positive phase of the NAO respectively. Higher than normal CO anomalies are observed during anticyclonic conditions (up to +1%) compared to cyclonic conditions. The cleanest conditions are observed when winds are northeasterly and during the enhanced negative phases of the NAO, when relatively clean Arctic air masses are transported over the Nordic regions in the both cases. In the case of nearly all weather states, the CO anomalies consistently continue to increase or decrease as the degree of persistency of a weather state is increased. The results of this sensitivity study further provide an observational basis for the process-oriented evaluation of chemistry transport models, especially with regard to the representation of large-scale coupling of chemistry and local weather states and its role in the long-range transport of pollutants in such models.

    Download full text (pdf)
    fulltext
  • 335.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Exploiting the favourable alignment of CALIPSO's descending orbital tracks over Sweden to study aerosol characteristics2013In: Tellus. Series B, Chemical and physical meteorology, ISSN 0280-6509, E-ISSN 1600-0889, Vol. 65, article id 21155Article in journal (Refereed)
    Abstract [en]

    One of the key knowledge gaps when estimating aerosol forcing and their role in air quality is our limited understanding of their vertical distribution. As an active lidar in space, the CALIOP-CALIPSO is helping to close this gap. The descending orbital track of CALIPSO follows elongated semi-major axis of Sweden, slicing its atmosphere every 2-3 d, thus providing a unique opportunity to characterise aerosols and their verticality in all seasons irrespective of solar conditions. This favourable orbital configuration of CALIPSO over Sweden is exploited in the present study. Using five years of night-time aerosol observations (2006-2011), we investigated the vertical distribution of aerosols. The role of temperature inversions and winds in governing this distribution is additionally investigated using collocated AIRS-Aqua and ERA-Interim Reanalysis data. It is found that the majority of aerosols (up to 70%) are located within 1 km above the surface in the lowermost troposphere, irrespective of the season. In summer, convection and stronger mixing lift aerosols to slightly higher levels, but their noticeable presence in the upper free troposphere is observed in the winter half of the year, when the boundary layer is decoupled due to strong temperature inversions separating local sources from the transport component. When southerly winds prevail, two or more aerosol layers are most frequent over southern Sweden and the polluted air masses have higher AOD values. The depolarisation ratio and integrated attenuated backscatter of these aerosol layers are also higher. About 30-50% of all aerosol layers are located below the level where temperature inversions peak. On the other hand, relatively cleaner conditions are observed when the winds have a northerly component.

    Download full text (pdf)
    fulltext
  • 336.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Kahnert, Michael
    SMHI, Research Department, Air quality.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Kokkola, H.
    Hansson, Ulf
    SMHI, Research Department, Climate research - Rossby Centre.
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Integration of prognostic aerosol-cloud interactions in a chemistry transport model coupled offline to a regional climate model2015In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, no 6, p. 1885-1898Article in journal (Refereed)
    Abstract [en]

    To reduce uncertainties and hence to obtain a better estimate of aerosol (direct and indirect) radiative forcing, next generation climate models aim for a tighter coupling between chemistry transport models and regional climate models and a better representation of aerosol-cloud interactions. In this study, this coupling is done by first forcing the Rossby Center regional climate model (RCA4) with ERA-Interim lateral boundaries and sea surface temperature (SST) using the standard cloud droplet number concentration (CDNC) formulation (hereafter, referred to as the 'stand-alone RCA4 version' or 'CTRL' simulation). In the stand-alone RCA4 version, CDNCs are constants distinguishing only between land and ocean surface. The meteorology from this simulation is then used to drive the chemistry transport model, Multiple-scale Atmospheric Transport and Chemistry (MATCH), which is coupled online with the aerosol dynamics model, Sectional Aerosol module for Large Scale Applications (SALSA). CDNC fields obtained from MATCH-SALSA are then fed back into a new RCA4 simulation. In this new simulation (referred to as 'MOD' simulation), all parameters remain the same as in the first run except for the CDNCs provided by MATCH-SALSA. Simulations are carried out with this model setup for the period 2005-2012 over Europe, and the differences in cloud microphysical properties and radiative fluxes as a result of local CDNC changes and possible model responses are analysed. Our study shows substantial improvements in cloud microphysical properties with the input of the MATCH-SALSA derived 3-D CDNCs compared to the stand-alone RCA4 version. This model setup improves the spatial, seasonal and vertical distribution of CDNCs with a higher concentration observed over central Europe during boreal summer (JJA) and over eastern Europe and Russia during winter (DJF). Realistic cloud droplet radii (CD radii) values have been simulated with the maxima reaching 13 mu m, whereas in the stand-alone version the values reached only 5 mu m. A substantial improvement in the distribution of the cloud liquid-water paths (CLWP) was observed when compared to the satellite retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) for the boreal summer months. The median and standard deviation values from the 'MOD' simulation are closer to observations than those obtained using the stand-alone RCA4 version. These changes resulted in a significant decrease in the total annual mean net fluxes at the top of the atmosphere (TOA) by -5 W m(-2) over the domain selected in the study. The TOA net fluxes from the 'MOD' simulation show a better agreement with the retrievals from the Clouds and the Earth's Radiant Energy System (CERES) instrument. The aerosol indirect effects are estimated in the 'MOD' simulation in comparison to the pre-industrial aerosol emissions (1900). Our simulations estimated the domain averaged annual mean total radiative forcing of -0.64 W m(-2) with a larger contribution from the first indirect aerosol effect (-0.57 W m(-2)) than from the second indirect aerosol effect (-0.14 W m(-2)).

    Download full text (pdf)
    fulltext
  • 337.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Suntharalingam, P.
    Pozzoli, L.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Kloster, S.
    Rast, S.
    Feichter, J.
    Lenton, T. M.
    Rate of non-linearity in DMS aerosol-cloud-climate interactions2011In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 11, no 21, p. 11175-11183Article in journal (Refereed)
    Abstract [en]

    The degree of non-linearity in DMS-cloud-climate interactions is assessed using the ECHAM5-HAMMOZ model by taking into account end-to-end aerosol chemistry-cloud microphysics link. The evaluation is made over the Southern oceans in austral summer, a region of minimal anthropogenic influence. In this study, we compare the DMS-derived changes in the aerosol and cloud microphysical properties between a baseline simulation with the ocean DMS emissions from a prescribed climatology, and a scenario where the DMS emissions are doubled. Our results show that doubling the DMS emissions in the current climate results in a non-linear response in atmospheric DMS burden and subsequently, in SO2 and H2SO4 burdens due to inadequate OH oxidation. The aerosol optical depth increases by only similar to 20% in the 30 degrees S-75 degrees S belt in the SH summer months. This increases the vertically integrated cloud droplet number concentrations (CDNC) by 25 %. Since the vertically integrated liquid water vapor is constant in our model simulations, an increase in CDNC leads to a reduction in cloud droplet radius of 3.4 % over the Southern oceans in summer. The equivalent increase in cloud liquid water path is 10.7 %. The above changes in cloud microphysical properties result in a change in global annual mean radiative forcing at the TOA of -1.4 W m(-2). The results suggest that the DMS-cloud microphysics link is highly non-linear. This has implications for future studies investigating the DMS-cloud climate feedbacks in a warming world and for studies evaluating geoengineering options to counteract warming by modulating low level marine clouds.

    Download full text (pdf)
    fulltext
  • 338.
    Thomas, Manu Anna
    et al.
    SMHI, Research Department, Air quality.
    Suntharalingam, P.
    Pozzoli, L.
    Rast, S.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Kloster, S.
    Feichter, J.
    Lenton, T. M.
    Quantification of DMS aerosol-cloud-climate interactions using the ECHAM5-HAMMOZ model in a current climate scenario2010In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 10, no 15, p. 7425-7438Article in journal (Refereed)
    Abstract [en]

    The contribution of ocean dimethyl sulfide (DMS) emissions to changes in cloud microphysical properties is quantified seasonally and globally for present day climate conditions using an aerosol-chemistry-climate general circulation model, ECHAM5-HAMMOZ, coupled to a cloud microphysics scheme. We evaluate DMS aerosol-cloud-climate linkages over the southern oceans where anthropogenic influence is minimal. The changes in the number of activated particles, cloud droplet number concentration (CDNC), cloud droplet effective radius, cloud cover and the radiative forcing are examined by analyzing two simulations: a baseline simulation with ocean DMS emissions derived from a prescribed climatology and one in which the ocean DMS emissions are switched off. Our simulations show that the model realistically simulates the seasonality in the number of activated particles and CDNC, peaking during Southern Hemisphere (SH) summer coincident with increased phyto-plankton blooms and gradually declining with a minimum in SH winter. In comparison to a simulation with no DMS, the CDNC level over the southern oceans is 128% larger in the baseline simulation averaged over the austral summer months. Our results also show an increased number of smaller sized cloud droplets during this period. We estimate a maximum decrease of up to 15-18% in the droplet radius and a mean increase in cloud cover by around 2.5% over the southern oceans during SH summer in the simulation with ocean DMS compared to when the DMS emissions are switched off. The global annual mean top of the atmosphere DMS aerosol all sky radiative forcing is -2.03 W/m(2), whereas, over the southern oceans during SH summer, the mean DMS aerosol radiative forcing reaches -9.32 W/m(2).

    Download full text (pdf)
    fulltext
  • 339.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Brannstrom, Niklas
    Persson, Christer
    SMHI, Professional Services.
    Grahn, Hakan
    von Schoenberg, Pontus
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Surface air quality implications of volcanic injection heights2017In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 166, p. 510-518Article in journal (Refereed)
  • 340.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Typical meteorological conditions associated with extreme nitrogen dioxide (NO2) pollution events over Scandinavia2017In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 19, p. 12071-12080Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 341.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Roberts, Malcolm
    Roberts, Christopher
    Lohmann, Katja
    A statistical and process-oriented evaluation of cloud radiative effects in high-resolution global models2019In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, no 4, p. 1679-1702Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 342.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    L'Ecuyer, Tristan
    Wang, Shiyu
    SMHI, Research Department, Climate research - Rossby Centre.
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Snowfall distribution and its response to the Arctic Oscillation: an evaluation of HighResMIP models in the Arctic using CPR/CloudSat observations2019In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, no 8, p. 3759-3772Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 343.
    Thomas, Manu
    et al.
    SMHI, Research Department, Air quality.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    Tjernstrom, Michael
    Ekman, Annica M. L.
    The Relation Between Aerosol Vertical Distribution and Temperature Inversions in the Arctic in Winter and Spring2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 5, p. 2836-2845Article in journal (Refereed)
    Download full text (pdf)
    fulltext
  • 344. Tilmes, S
    et al.
    Brandt, J
    Flatoy, F
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Flemming, J
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Christensen, J H
    Frohn, L M
    Hov, O
    Jacobsen, I
    Reimer, E
    Stern, R
    Zimmermann, J
    Comparison of five eulerian air pollution forecasting systems for the summer of 1999 using the German ozone monitoring data2002In: Journal of Atmospheric Chemistry, ISSN 0167-7764, E-ISSN 1573-0662, Vol. 42, no 1, p. 91-121Article in journal (Refereed)
    Abstract [en]

    Eulerian state-of-the-art air pollution forecasting systems on the European scale are operated routinely by several countries in Europe. DWD and FUB, both Germany, NERI, Denmark, NILU, Norway, and SMHI, Sweden, operate some of these systems. To apply such modeling systems, e.g. for regulatory purposes according to new EU directives, an evaluation and comparison of the model systems is fundamental in order to assess their reliability. One step in this direction is presented in this study: The model forecasts from all five systems have been compared to measurements of ground level ozone in Germany. The outstanding point in this investigation is the availability of a huge amount of data - from forecasts by the different model systems and from observations. This allows for a thorough interpretation of the findings and assures the significance of the observed features. Data from more than 300 measurement stations for a 5-month period (May-September 1999) of the German monitoring networks have been used in this comparison. Different spatial and temporal statistical parameters were applied in the evaluation. Generally, it was found that the most comprehensive models gave the best results. However, the less comprehensive and computational cheaper models also produced good results. The extensive comparison made it possible to point out weak points in the different models and to describe the individual model behavior for a full summer period in a climatological sense. The comparison also gave valuable information for an assessment of individual measurement stations and complete monitoring networks in terms of the representativeness of the observation data.

  • 345. van der Gon, H. A. C. Denier
    et al.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Fountoukis, C.
    Johansson, C.
    Pandis, S. N.
    Simpson, D.
    Visschedijk, A. J. H.
    Particulate emissions from residential wood combustion in Europe revised estimates and an evaluation2015In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 15, no 11, p. 6503-6519Article in journal (Refereed)
    Abstract [en]

    Currently residential wood combustion (RWC) is increasing in Europe because of rising fossil fuel prices but also due to climate change mitigation policies. However, especially in small-scale applications, RWC may cause high emissions of particulate matter (PM). Recently we have developed a new high-resolution (7 x 7 km) anthropogenic carbonaceous aerosol emission inventory for Europe. The inventory indicated that about half of the total PM2.5 emission in Europe is carbonaceous aerosol and identified RWC as the largest organic aerosol source in Europe. The inventory was partly based on national reported PM emissions. Use of this organic aerosol inventory as input for two chemical transport models (CTMs), PMCAMx and EMEP MSC-W, revealed major underestimations of organic aerosol in winter time, especially for regions dominated by RWC. Interestingly, this was not universal but appeared to differ by country. In the present study we constructed a revised bottom-up emission inventory for RWC accounting for the semivolatile components of the emissions. The revised RWC emissions are higher than those in the previous inventory by a factor of 2-3 but with substantial inter-country variation. The new emission inventory served as input for the CTMs and a substantially improved agreement between measured and predicted organic aerosol was found. The revised RWC inven-tory improves the model-calculated organic aerosol significantly. Comparisons to Scandinavian source apportionment studies also indicate substantial improvements in the modelled wood-burning component of organic aerosol. This suggests that primary organic aerosol emission inventories need to be revised to include the semivolatile organic aerosol that is formed almost instantaneously due to dilution and cooling of the flue gas or exhaust. Since RWC is a key source of fine PM in Europe, a major revision of the emission estimates as proposed here is likely to influence source-receptor matrices and modelled source apportionment. Since usage of biofuels in small combustion units is a globally significant source, the findings presented here are also relevant for regions outside of Europe.

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

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

  • 347. van Pul, Addo
    et al.
    Hertel, Ole
    Geels, Camilla
    Dore, Anthony J.
    Massimo, Vieno
    van Jaarsveld, Hans A.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Schaap, Martijn
    Fagerli, Hilde
    Modelling of the Atmospheric Transport and Deposition of Ammonia at a National and Regional Scale2009In: in Atmospheric Ammonia - Detecting emission changes and environmental impacts., Springer, 2009, p. 301-356Chapter in book (Other academic)
  • 348. van Pul, Addo
    et al.
    Reis, Stefan
    Dore, Tony
    Xuejun, Liu
    Hilde, Fagerli
    Geels, Camilla
    Hertel, Ole
    Kruijt Roy, Wichink
    Kryza, Maciej
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Vieno, Massimo
    Ron, Smith
    Eiko, Nemitz
    Modelling the National and Regional Transport and Deposition of Ammonia2009In: Atmospheric Ammonia - Detecting emission changes and environmental impacts., Springer, 2009, p. 409-421Chapter in book (Other academic)
  • 349. Vautard, R.
    et al.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Foltescu, Valentin
    SMHI.
    Graff, A.
    Kerschbaumer, A.
    Krol, M.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    Wind, P.
    Skill and uncertainty of a regional air quality model ensemble2009In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 43, no 31, p. 4822-4832Article in journal (Refereed)
    Abstract [en]

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

  • 350. Vautard, R.
    et al.
    Van Loon, M.
    Schaap, M.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Brandt, J.
    Builtjes, P. J. H.
    Christensen, J. H.
    Cuvelier, C.
    Graff, A.
    Jonson, J. E.
    Krol, M.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Roberts, P.
    Rouil, L.
    Stern, R.
    Tarrason, L.
    Thunis, P.
    Vignati, E.
    White, L.
    Wind, P.
    Is regional air quality model diversity representative of uncertainty for ozone simulation?2006In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 33, no 24, article id L24818Article in journal (Refereed)
    Abstract [en]

    We examine whether seven state-of-the-art European regional air quality models provide daily ensembles of predicted ozone maxima that encompass observations. Using tools borrowed from the evaluation of ensemble weather forecasting, we analyze statistics of simulated ensembles of ozone daily maxima over an entire summer season. Although the model ensemble overestimates ozone, the distribution of simulated concentrations is representative of the uncertainty. The spread of simulations is due to random fluctuations resulting from differences in model formulations and input data, but also to the spread between individual model systematic biases. The ensemble average skill increases as the spread decreases. The skill of the ensemble in giving probabilistic predictions of threshold exceedances is also demonstrated. These results allow for optimism about the ability of this ensemble to simulate the uncertainty of the impact of emission control scenarios.

45678 301 - 350 of 362
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf