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  • 1.
    Andersson, Camilla
    et al.
    SMHI, Research Department, Air quality.
    Alpfjord, Helene
    SMHI, Professional Services.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Karlsson, Per Erik
    Miljöforskningsinstitutet.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Reanalysis of and attribution to near-surface ozone concentrations in Sweden during 1990-20132017In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 17, no 22Article in journal (Refereed)
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  • 2.
    Andersson, Camilla
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Thomas, Manu
    SMHI, Research Department, Air quality.
    Korhonen, H.
    Lehtinen, K. E. J.
    Kokkola, H.
    MATCH-SALSA - Multi-scale Atmospheric Transport and CHemistry model coupled to the SALSA aerosol microphysics model - Part 1: Model description and evaluation2015In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, no 2, p. 171-189Article in journal (Refereed)
    Abstract [en]

    We have implemented the sectional aerosol dynamics model SALSA (Sectional Aerosol module for Large Scale Applications) in the European-scale chemistry-transport model MATCH (Multi-scale Atmospheric Transport and Chemistry). The new model is called MATCH-SALSA. It includes aerosol microphysics, with several formulations for nucleation, wet scavenging and condensation. The model reproduces observed higher particle number concentration (PNC) in central Europe and lower concentrations in remote regions. The modeled PNC size distribution peak occurs at the same or smaller particle size as the observed peak at four measurement sites spread across Europe. Total PNC is underestimated at northern and central European sites and accumulation-mode PNC is underestimated at all investigated sites. The low nucleation rate coefficient used in this study is an important reason for the underestimation. On the other hand, the model performs well for particle mass (including secondary inorganic aerosol components), while elemental and organic carbon concentrations are underestimated at many of the sites. Further development is needed, primarily for treatment of secondary organic aerosol, in terms of biogenic emissions and chemical transformation. Updating the biogenic secondary organic aerosol (SOA) scheme will likely have a large impact on modeled PM2.5 and also affect the model performance for PNC through impacts on nucleation and condensation.

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  • 3.
    Andersson, Camilla
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Thomas, Manu
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Kokkola, Harri
    FMI.
    Lehtinen, Kari
    FMI.
    MATCH-SALSA: Multi-scale Atmospheric Transport and CHemistry model coupled to the SALSA aerosol microphysics model2013Report (Other academic)
    Abstract [en]

    This report presents a new aerosol dynamics version of a European scale Eulerian CTM, MATCH. The new model is called MATCH-SALSA, and includes aerosol microphysics and several options for nucleation, wet scavenging and condensation. The report entails model description, evaluation and sensitivity tests.The new model reproduces observed higher particle number concentration (PNC) in central Europe and lower in remote regions. The model peak PNC occurs at the same particle size as the observed peak or at smaller sizes, which indicate missing growth. Total PNC is underestimated at some sites. The model performs well for particle mass, including SIA components. EC and OC are underestimated at many of the sites.The results are sensitive to the fraction of SOx emitted as H2SO4 and the optimum choice is site dependent. The model results are highly sensitive to whether organic nucleation is included or not. The model results are sensitive to amount of organic vapors in the condensation. The model can be used in applications knowing the restrictions of what the model manages well and what needs further improvements, which is detailed in the report.

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    FULLTEXT01
  • 4.
    Andersson, Stefan
    et al.
    SMHI, Research Department, Air quality.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Känslighetsanalys, vidareutveckling och validering av SIMAIRs urbana spridningsmodell BUM2010Report (Other academic)
    Abstract [en]

    The urban background dispersion model, BUM, used in the SIMAIR-system, is a simple trajectory model for evaluation of Air Quality in urban areas on 1 x 1 km spatial resolution. The urban contribution to concentrations in a receptor point is calculated from the emission sources in an upstream influence area whose size is dependent on the wind speed. This simple and attractive concept enables fast model calculations and the model is applied for more than 100 Swedish towns within SIMAIR. However, comparison with measured concentrations has shown that BUM underestimates levels of NO2 and NOX, especially for towns in northern Sweden. The reason for this is probably meteorological, i.e. it exemplifies the difficulties in describing the dispersion of air pollutants during strong stable atmospheric conditions. This problem has previously been solved by a statistical method (regression analysis), to adjust the calculations against measurements for towns in northern Sweden. The result of this method has varied widely; for some urban areas the result has been good while the correlation between measured and calculated concentrations has been lower for others. The aim of this study is, through a sensitivity analysis, to examine the parameters of the model that most significantly affect the levels of NO2, and subsequently improve the parametrization of these during stable atmospheric conditions. Furthermore, the results are validated against measurements from 13 urban areas in Sweden. According to the sensitivity analysis, it is the parametrization of the vertical dispersion parameter σz that most affects the levels of NO2. A new parametrization, which takes into account the stability, is introduced for urban areas outside major cities. This generally raises the concentrations with several μgm-3 on annual basis and 10’s μgm-3 for 98-percentile daily mean concentration. Furthermore, a correction of the meteorology (from Mesan) is introduced used in the calculations of BUM, for the meteorology to represent more urban (rough) conditions. The improvements of BUM lead to a better consistency between the model and the measurements. Generally, the correlation between the calculated and the measured concentrations of NO2 increases, and the time variation of concentrations is better captured in the model. Annual averages, and especially 98-percentile daily- and hourly mean value, are better reproduced in the improved version of BUM; when compared to measured concentrations, 37 % of data points are within ± 50 % for the original BUM while the corresponding results for the new BUM is 95 %. However, the new BUM model still doesn’t succeed, for all towns in northern Sweden, to fully reproduce the highest daily and hourly peaks of concentrations. In comparison with the original BUM climate corrected concentrations (in northern Sweden), the correlation between calculated and measured concentrations is higher for the new BUM, especially in terms of annual average, correlation coefficient and coefficient of variation.

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  • 5. Barre, Jerome
    et al.
    Petetin, Herve
    Colette, Augustin
    Guevara, Marc
    Peuch, Vincent-Henri
    Rouil, Laurence
    Engelen, Richard
    Inness, Antje
    Flemming, Johannes
    Garcia-Pando, Carlos Perez
    Bowdalo, Dene
    Meleux, Frederik
    Geels, Camilla
    Christensen, Jesper H.
    Gauss, Michael
    Benedictow, Anna
    Tsyro, Svetlana
    Friese, Elmar
    Struzewska, Joanna
    Kaminski, Jacek W.
    Douros, John
    Timmermans, Renske
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Adani, Mario
    Jorba, Oriol
    Joly, Mathieu
    Kouznetsov, Rostislav
    Estimating lockdown-induced European NO2 changes using satellite and surface observations and air quality models2021In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 21, no 9, p. 7373-7394Article in journal (Refereed)
    Abstract [en]

    This study provides a comprehensive assessment of NO2 changes across the main European urban areas induced by COVID-19 lockdowns using satellite retrievals from the Tropospheric Monitoring Instrument (TROPOMI) onboard the Sentinel-5p satellite, surface site measurements, and simulations from the Copernicus Atmosphere Monitoring Service (CAMS) regional ensemble of air quality models. Some recent TROPOMI-based estimates of changes in atmospheric NO2 concentrations have neglected the influence of weather variability between the reference and lockdown periods. Here we provide weather-normalized estimates based on a machine learning method (gradient boosting) along with an assessment of the biases that can be expected from methods that omit the influence of weather. We also compare the weather-normalized satellite-estimated NO2 column changes with weather-normalized surface NO2 concentration changes and the CAMS regional ensemble, composed of 11 models, using recently published estimates of emission reductions induced by the lockdown. All estimates show similar NO2 reductions. Locations where the lockdown measures were stricter show stronger reductions, and, conversely, locations where softer measures were implemented show milder reductions in NO2 pollution levels. Average reduction estimates based on either satellite observations (-23 %), surface stations (-43 %), or models (-32 %) are presented, showing the importance of vertical sampling but also the horizontal representativeness. Surface station estimates are significantly changed when sampled to the TROPOMI overpasses (-37 %), pointing out the importance of the variability in time of such estimates. Observation-based machine learning estimates show a stronger temporal variability than model-based estimates.

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    Estimating lockdown-induced European NO2 changes using satellite and surface observations and air quality models
  • 6. Brenot, Hugues
    et al.
    Theys, Nicolas
    Clarisse, Lieven
    van Gent, Jeroen
    Hurtmans, Daniel R.
    Vandenbussche, Sophie
    Papagiannopoulos, Nikolaos
    Mona, Lucia
    Virtanen, Timo
    Uppstu, Andreas
    Sofiev, Mikhail
    Bugliaro, Luca
    Vazquez-Navarro, Margarita
    Hedelt, Pascal
    Parks, Michelle Maree
    Barsotti, Sara
    Coltelli, Mauro
    Moreland, William
    Scollo, Simona
    Salerno, Giuseppe
    Arnold-Arias, Delia
    Hirtl, Marcus
    Peltonen, Tuomas
    Lahtinen, Juhani
    Sievers, Klaus
    Lipok, Florian
    Rufenacht, Rolf
    Haefele, Alexander
    Hervo, Maxime
    Wagenaar, Saskia
    de Cerff, Wim Som
    de Laat, Jos
    Apituley, Arnoud
    Stammes, Piet
    Laffineur, Quentin
    Delcloo, Andy
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rokitansky, Carl-Herbert
    Vargas, Arturo
    Kerschbaum, Markus
    Resch, Christian
    Zopp, Raimund
    Plu, Matthieu
    Peuch, Vincent-Henri
    Van Roozendael, Michel
    Wotawa, Gerhard
    EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds2021In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 21, no 11, p. 3367-3405Article in journal (Refereed)
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    EUNADICS-AV early warning system dedicated to supporting aviation in the case of a crisis from natural airborne hazards and radionuclide clouds
  • 7. Galmarini, S.
    et al.
    Bonnardot, F.
    Jones, A.
    Potempski, S.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Martet, M.
    Multi-model vs. EPS-based ensemble atmospheric dispersion simulations: A quantitative assessment on the ETEX-1 tracer experiment case2010In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 44, no 29, p. 3558-3567Article in journal (Refereed)
    Abstract [en]

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

  • 8. Hirtl, Marcus
    et al.
    Arnold, Delia
    Baro, Rocio
    Brenot, Hugues
    Coltelli, Mauro
    Eschbacher, Kurt
    Hard-Stremayer, Helmut
    Lipok, Florian
    Maurer, Christian
    Meinhard, Dieter
    Mona, Lucia
    Mulder, Marie D.
    Papagiannopoulos, Nikolaos
    Pernsteiner, Michael
    Plu, Matthieu
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rokitansky, Carl-Herbert
    Scherllin-Pirscher, B.
    Sievers, Klaus
    Sofiev, Mikhail
    de Cerff, Wim Jan Som
    Steinheimer, Martin
    Stuefer, Martin
    Theys, Nicolas
    Uppstu, Andreas
    Wagenaar, Saskia
    Winkler, Roland
    Wotawa, Gerhard
    Zobl, Fritz
    Zopp, Raimund
    A volcanic-hazard demonstration exercise to assess and mitigate the impacts of volcanic ash clouds on civil and military aviation2020In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 20, no 6, p. 1719-1739Article in journal (Refereed)
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    A volcanic-hazard demonstration exercise to assess and mitigate the impacts of volcanic ash clouds on civil and military aviation
  • 9. Huijnen, V.
    et al.
    Eskes, H. J.
    Poupkou, A.
    Elbern, H.
    Boersma, K. F.
    Foret, G.
    Sofiev, M.
    Valdebenito, A.
    Flemming, J.
    Stein, O.
    Gross, A.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    D'Isidoro, M.
    Kioutsioukis, I.
    Friese, E.
    Amstrup, B.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Strunk, A.
    Vira, J.
    Zyryanov, D.
    Maurizi, A.
    Melas, D.
    Peuch, V-H
    Zerefos, C.
    Comparison of OMI NO2 tropospheric columns with an ensemble of global and European regional air quality models2010In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 10, no 7, p. 3273-3296Article in journal (Refereed)
    Abstract [en]

    We present a comparison of tropospheric NO2 from OMI measurements to the median of an ensemble of Regional Air Quality (RAQ) models, and an intercomparison of the contributing RAQ models and two global models for the period July 2008 - June 2009 over Europe. The model forecasts were produced routinely on a daily basis in the context of the European GEMS ("Global and regional Earth-system (atmosphere) Monitoring using Satellite and in-situ data") project. The tropospheric vertical column of the RAQ ensemble median shows a spatial distribution which agrees well with the OMI NO2 observations, with a correlation r=0.8. This is higher than the correlations from any one of the individual RAQ models, which supports the use of a model ensemble approach for regional air pollution forecasting. The global models show high correlations compared to OMI, but with significantly less spatial detail, due to their coarser resolution. Deviations in the tropospheric NO2 columns of individual RAQ models from the mean were in the range of 20-34% in winter and 40-62% in summer, suggesting that the RAQ ensemble prediction is relatively more uncertain in the summer months. The ensemble median shows a stronger seasonal cycle of NO2 columns than OMI, and the ensemble is on average 50% below the OMI observations in summer, whereas in winter the bias is small. On the other hand the ensemble median shows a somewhat weaker seasonal cycle than NO2 surface observations from the Dutch Air Quality Network, and on average a negative bias of 14%. Full profile information was available for two RAQ models and for the global models. For these models the retrieval averaging kernel was applied. Minor differences are found for area-averaged model columns with and without applying the kernel, which shows that the impact of replacing the a priori profiles by the RAQ model profiles is on average small. However, the contrast between major hotspots and rural areas is stronger for the direct modeled vertical columns than the columns where the averaging kernels are applied, related to a larger relative contribution of the free troposphere and the coarse horizontal resolution in the a priori profiles compared to the RAQ models. In line with validation results reported in the literature, summertime concentrations in the lowermost boundary layer in the a priori profiles from the DOMINO product are significantly larger than the RAQ model concentrations and surface observations over the Netherlands. This affects the profile shape, and contributes to a high bias in OMI tropospheric columns over polluted regions. The global models indicate that the upper troposphere may contribute significantly to the total column and it is important to account for this in comparisons with RAQ models. A combination of upper troposphere model biases, the a priori profile effects and DOMINO product retrieval issues could explain the discrepancy observed between the OMI observations and the ensemble median in summer.

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  • 10.
    Häggkvist, Kenneth
    et al.
    SMHI, Professional Services.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridningsberäkningar rörande gasutsläpp från ett antal källor inom SSAB Luleå-verken1986Report (Other academic)
  • 11. Kovalets, Ivan V.
    et al.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Didkivska, Svitlana N.
    Ievdin, Ievgen A.
    Trybushnyi, Dmytro
    Calculation of the far range atmospheric transport of radionuclides after the Fukushima accident with the atmospheric dispersion model MATCH of the JRODOS system2014In: International Journal of Environment and Pollution, ISSN 0957-4352, E-ISSN 1741-5101, Vol. 54, no 2-4, p. 101-109Article in journal (Refereed)
    Abstract [en]

    The paper presents estimates of the far-range atmospheric dispersion of radionuclides after the accident at Fukushima Daiichi Nuclear Power Plant (NPP), obtained using the long-range atmospheric dispersion model MATCH. Software tools were developed to run MATCH in the EU nuclear emergency response system JRODOS using freely available numerical weather prediction (NWP) data of the Global Forecasting System (GFS) operated by the United States National Center of Environmental Prediction (NCEP). Comparisons are made of results with JRODOS/MATCH and a standalone MATCH operated by Swedish Meteorological and Hydrological Institute (SMHI) driven by the European Center for Medium-Range Weather Forecasts (ECMWF) NWP data.

  • 12.
    Kvick, Tord
    et al.
    SMHI.
    Krieg, Roland
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Vindförhållandena i Sveriges kust- och havsband, rapport nr 21986Report (Other academic)
    Abstract [sv]

    Med syfte att ta fram vindenergi kartor för de svenska kust- och havsområdena har vi gått vidare med de havsvindstudier som genomfördes av SMHI 1983-84.

    Vi har dels kunnat analysera längre tidsserier av mätdata från kasunfyrar och dels gjort ytterligare simuleringar med den dynamiska vindfältsmodellen som i detta projekt utnyttjas med några smärre modifieringar.

    De mätdata som nu utnyttjats är 5-7.5 års timvisa vinddata från sju kasunfyrar där SMHI har automatiska väderstationer placerade.Dessa mätningar görs på 25-35 meters höjd över havsytan och i områden som är fria från öar. Uppmätta data har korrigerats med hänsyn till de störningar i vindströmningen som  uppstår runt fyrkropparna.

    Den dynamiska vindfältsmodell vi arbetat med beskrevs första gången av Danard ( 1977) och är en enkel en-nivås 2 dimensionell primitiv ekvationsmodell. Den mindre skalans vind erhålles genom en dynamisk tolkning av den stora skalan.

    De mesoskaliga effekter som parametriseras i modellen och ligger till grund för den dynamiska tolkningen är:

    • friktionseffekter
    • topografin
    • värmeflödet från underlaget

    Mer i detalj innebär detta att vi för den stora skalans karaktäristik utnyttjat den geostrofiska vinden samt temperatur och geopotentialanalyser från marken, 850 mb och 700 mb. Den lilla skalans egenskaper beskrivs genom en digitalisering av topografin och skrovligheten i ett gridnät.

    I denna studie har vi minskat avståndet mellan grid- eller beräkningspunkterna från 22 km till 11 km och utökat den simulerade tidsperioden från tre till tolv månader. Beräkningsområdet omfattar södra Sverige upp till Gävlebukten samt angränsande områden i väster och öster.

    Slutresultaten redovisas i form av medianvindens fördelning för 100 m nivån i kartskalan 1: 2500000 och i form av rörelseenergikartor för 100 meters höjd i skalan 1: 1250000. De senare kan sammanfattas i följande punkter.

    • Vindenergipotentialen är ca 40% högre vid den bästa kasunfyrsplatserna,Trubaduren, än vid den sämsta, Gustav Dahlen.
    • 10-15 km ut från land är vindenergipotentialen i regel 35-45%högre än vid de land lägen som ligger närmast stranden.
    • De mest vindrika områdena längs de svenska kusterna finns, enligt vad som framkommit i denna studie, längs hela västkustenoch sydväst om Falsterbo, syd och öst om Öland, nordväst om Gotland och i Alands hav.
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  • 13.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Concentration and deposition of acidifying air pollutants over Sweden: Estimates for 1991 based on the match model and observations1995In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 85, no 4, p. 2021-2026Article in journal (Refereed)
    Abstract [en]

    The MATCH (Mesoscale Atmospheric Transport and CHemistry) model has been developed as a tool for air pollution assessment studies on different geographical scales. MATCH is an Eulerian atmospheric dispersion model, including physical and chemical processes governing sources, atmospheric transport and sinks of oxidized sulfur and oxidized and reduced nitrogen. Using a combination of air and precipitation chemistry measurements and the MATCH model, the national and long-range transport contributions to air pollution and deposition can be quantified in the model region. The calculations for the year 1991 show that the Swedish import was about 4.5 times larger than the export for sulfur and about six times larger for reduced nitrogen, while the Swedish import of oxidized nitrogen only exceeded the export by 10%. Using the MATCH system we estimate the long-range transport in an independent way compared to EMEP. Comparison between the EMEP and MATCH calculations for 1991 show that the total deposition of oxidized nitrogen over Sweden is similar, while the EMEP-values for total deposition of oxidized sulfur and reduced nitrogen are 25% respectively 40% smaller than what is obtained from MATCH.

  • 14.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Air pollution Assessment Study Using the MATCH Modelling System: Application to sulfur and nitrogen compounds over Sweden 19941996Report (Other academic)
    Abstract [en]

    The MATCH (Mesoscale Atmospheric Transport and CHemistry) model has been developed as a tool for air pollution assessment studies on different geographical scales. The MATCH system is based on an Eulerian atmospheric transport model, including physical and chemical processes governing sources, atmospheric transport and sinks of oxidised sulphur and oxidised and reduced nitrogen. With the MATCH system, air pollution contributions from different source types like traffic, industry, shipping, farming etc. can be obtained. Using a combination of air and precipitation chemistry measurements and the MATCH dispersion model, the contribution of air pollution and deposition from long-range transport can be quantified in the model region. The calculations for the year 1994 show that the Swedish import was 5.5 times larger than the export for sulphur and 4.4 times larger for reduced nitrogen, while the Swedish import of oxidised nitrogen only exceeded the export by 10%.

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  • 15.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Validation of the operational emergency response model at the Swedish Meteorological and Hydrological Institute using data from ETEX and the Chernobyl accident1998In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 32, no 24, p. 4325-4333Article in journal (Refereed)
    Abstract [en]

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

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

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

  • 17. Marecal, V.
    et al.
    Peuch, V. -H
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Andersson, S.
    Arteta, J.
    Beekmann, M.
    Benedictow, A.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bessagnet, B.
    Cansado, A.
    Cheroux, F.
    Colette, A.
    Coman, A.
    Curier, R. L.
    van der Gon, H. A. C. Denier
    Drouin, A.
    Elbern, H.
    Emili, E.
    Engelen, R. J.
    Eskes, H. J.
    Foret, G.
    Friese, E.
    Gauss, M.
    Giannaros, C.
    Guth, J.
    Joly, M.
    Jaumouille, E.
    Josse, B.
    Kadygrov, N.
    Kaiser, J. W.
    Krajsek, K.
    Kuenen, J.
    Kumar, U.
    Liora, N.
    Lopez, E.
    Malherbe, L.
    Martinez, I.
    Melas, D.
    Meleux, F.
    Menut, L.
    Moinat, P.
    Morales, T.
    Parmentier, J.
    Piacentini, A.
    Plu, M.
    Poupkou, A.
    Queguiner, S.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rouil, L.
    Schaap, M.
    Segers, A.
    Sofiev, M.
    Tarasson, L.
    Thomas, Manu Anna
    SMHI, Research Department, Air quality.
    Timmermans, R.
    Valdebenito, A.
    van Velthoven, P.
    van Versendaal, R.
    Vira, J.
    Ung, A.
    A regional air quality forecasting system over Europe: the MACC-II daily ensemble production2015In: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 8, no 9, p. 2777-2813Article in journal (Refereed)
    Abstract [en]

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

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  • 18.
    Meuller, Lars
    et al.
    SMHI.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Andersson, Erik
    SMHI.
    Gustavsson, Nils
    Meterologi.
    Meso-g scale objective analysis of near surface temperature, humidity and wind, and its application in air pollution modelling1990Report (Other academic)
    Abstract [en]

    Within the PROMIS project at the Swedish Meteorological and Hydrological Institute a meso-scale network of automatic weather observing stations was established for several purposes . For several of these applications it was considered advantageous to process the data by applying an objective analysis, including quality control , on the observed data to a regular grid.

    The analysis system, which is in operational use since a couple of years, is described in this report. The system is based on the meso scale analysis system described in PROMIS Report Nr 1, modified to the finer resolution on the meso-y scale.

    In the analysis of the surface wind a new approach is used, where the wind is divided into a divergent anda non-divergent part, which is shown to give a better description of the local wind field.

    The report also gives example of how the analysed fields can be used in dispersion modelling.

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    fulltext
  • 19.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Regional spridningsmodell för Göteborgs och Bohus, Hallands och Älvsborgs län: Regional luftmiljöanalys för år 19911994Report (Other academic)
    Abstract [en]

    MATCH-Västkusten is a dispersion model for the three counties of Göteborg-Bohus, Hallandand Älvsborg on the Swedish west-coast. MATCH stands for "Mesoscale Atmospheric Transportand CHemistry model" and is an Eulerian atmospheric dispersion model, including physicaland chemical processes goveming sources, atmospheric transport and sinks of oxidizedsulphur and oxidized and reduced nitrogen.U sing the MATCH-Västkusten system, air pollution contributions from diff erent source typeslike traffic, industry, shipping, farming etc. can be obtained. Using a combination of air andprecipitation chemistry measurements and the MATCH-Västkusten model, also the contributionof air pollution and deposition from long range transport can be quantified in the model region.In the report, many results from the air pollution assessment studies for the year 1991 arepresented. As examples of result can be mentioned that the sources within the west-coastregion account for a substantial fraction of the total NO2-concentration, while the deposition ofsulphur and nitrogen is dominated by the long range transport. Detailed values of the differentcontributions are given in the report.

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  • 20.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridnings- och depositionsberäkningar för en sopförbränningsanläggning i Skövde1986Report (Other academic)
  • 21.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridningsberäkningar rörande gasutsläpp vid ScanDust i Landskrona - bestämning av cyanväte1987Report (Other academic)
  • 22.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Grennfelt, P.
    IVL.
    Kindbom, K.
    IVL.
    Lövblad, Gun
    IVL Swedish Environmental Research Institute.
    Svanberg, P-A
    IVL.
    Luftföroreningsepisoden över södra Sverige 2–4 februari 19871987Report (Other academic)
    Abstract [en]

    During the period 2-4 February 1987 one of the most severe episodes of polluted air, which has ever been registered in Sweden, occured over southern Sweden.The sulfur dioxide concentrations reached at that time daily mean values around 300 μg m-3 in background as well as in urban areas. The sulfur dioxide concentrations were in urban areas along the Swedish west coast 10- 20 times higher and in background areas 40-50 times higher than the normal mean levels of sulfur dioxide at the corresponding places. Also higher concentrations of nitrogen oxides and soot occured.The meteorological transport calculations show that very large sulfur emissions in Central Europe had contaminated the air that reached southern Sweden during the period 2-4 February. The emissions of sulfur dioxide and soot in Central Europe were extremely large due to the very cold weather. During the period very stable stratification occured in the lower parts of the atmosphere, which caused very limited turbulent dispersion and dilution of the air pollutants. The high concentrations of sulfur dioxide and soot, which occured over southern Sweden , were to a larger part (about 90% or more) caused by the long range transport of air pollutants.

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  • 23.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Häggkvist, Kenneth
    SMHI, Professional Services.
    Spridningsberäkningar, SSAB - Luleå-verken1986Report (Other academic)
    Abstract [sv]

    Spridningsberäkningar har utförts för ett par större utsläpp, av haveri­karaktär, från en större masugnsklocka. Utsläppen avser relativt stora gasflöden (20 000 m3 respektive 50 000 m3 ) under kort tid (5 respektive 15 min) och studien har syftat till att bestämma halter av CO och H2S i omgivningen samt områden där risk för explosion kan förekomma. Nedan ges en sammanfattande redovisning av resultaten. Av tabell 1 ( sid 2) framgår hur utsläppen specificerats, och de i tabellen angivna beteckning­arna för respektive fall utnyttjas i sammanfattningen nedan.

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  • 24.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Thaning, Lennart
    FOA.
    Model for Simulation of Air and Ground Contamination Associated with Nuclear Weapons. An Emergency Preparedness Model2000Report (Other academic)
    Abstract [en]

    A nuclear weapon explosion above ground can cause tremendous damage within thearea of some tens of kilometres from the explosion point due to direct damage throughthe blast wave, thermal radiation and initial nuclear radiation. Serious radiationprotection problems can also appear on very large distances, due to large amounts ofradioactive particles being transported by the winds and deposited in areas far awayfrom the explosion. Which areas to be affected are entirely determined by the characterof the explosion and the present weather situation. In such situations the possibility tosimulate and forecast in an accurate way the transport and deposition of radioactivesubstances, caused by the nuclear explosion, can be of fundamental importance in theradiation protection work. Studies of vulnerability and exercises within the civilpreparedness also demand realistic simulations. Transport and dispersion in theatmosphere over large distances (ca 200 - 4000 km) includes many complex processesand the only possibility to make a realistic description is to use a computeriseddispersion model.

    The access to measured atmospheric chemistry or radiological data, which can beutilised for the development of a dispersion model for nuclear weapon explosions, isvery limited. Therefore two in principal different models have been developed andutilised in the present study, on one hand PELLO at FOA, on the other hand MATCH atSMHI. The model comparisons have given both better understanding of the importanceof different processes and reduced the risk for severe errors in the models. The PELLOmodel is a so-called particle model (Random Displacement Model) in which a largeamount of particles, with diff erent sizes and characteristics, are emitted and traced. TheMATCH model is basically a so-called Eulerian model, where concentration of particlesand deposition are described in a high-resolution three-dimensional grid.

    A module describing the emission distribution of particle sizes at different types ofnuclear weapon explosions has been formulated and is used in both models. Themeteorological input data to both models is numerical weather analyses and forecasts.This weather information can be obtained from the European scale HIRLAM (HlghResolution Limited Area Model) weather forecast model at SMHI or from the globalmodel at ECMWF (European Centre for Medium Weather Forecasts).

    The MATCH model, adjusted to simulations of explosions of nuclear weapons, is nowincluded in the 24h preparedness at SMHI where real time weather data is available.Exercises are performed for the involved staff. Results from dispersion calculations canin real time be transmitted to a homepage on Internet with restricted access only forinvolved Swedish authorities. Besides, both dispersion models can be utilised assimulation tools at FOA and SMHI to produce the basis for different types of exercisesand studies.

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  • 25.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Kindbom, Karin
    IVL Swedish Environmental Research Institute.
    Sjöberg, Karin
    IVL Swedish Environmental Research Institute.
    The Swedish Precipitation Chemistry Network: Studies in network design usting the MATCH modelling system and statistical methods1996Report (Other academic)
    Abstract [en]

    In this study the Swedish Precipitation Chemistry Network has been examined thoroughly, including investigations into the representativeness of stations as well as into possibilities of time trend analysis. A suggestion of a new optimized network design is given.

    Using the MATCH modelling system, which has been developed as a tool for air pollution assessment studies, it has been possible to evaluate different hypothetical precipitation chemistry networks over Sweden. There is a clear indication from the different model experiments, focused on sulphur and nitrogen, that a proposed future reduction of the number of Swedish precipitation chemistry stations by about one third only has a small effect on the obtained annual and monthly wet deposition pattern over Sweden. Long-term changes in wet deposition can still be followed using this less dense station network. Comparisons with independent measurements indicate that errors in the MATCH system estirnates for sulphur and nitrogen are of the same size as for parallel measurements as long as the MATCH system has a sufficient number of high quality precipitation chernistry stations available for the region.

    A study of former results on wet deposition, using multivariate analysis, has clearly indicated that the base-cation deposition exhibits larger local variations than is the case for sulphur and nitrogen. Modelling of base-cation deposition is however not included in this study. The suggested reduction of the precipitation network is thus characterized by some caution, partly due to the base-cation deposition not being thoroughly investigated. Care has been taken not to diminish future possibilities in mapping base-cation deposition over Sweden.

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  • 26. Plu, Matthieu
    et al.
    Scherllin-Pirscher, Barbara
    Arnold Arias, Delia
    Baro, Rocio
    Bigeard, Guillaume
    Bugliaro, Luca
    Carvalho, Ana Cristina
    SMHI, Research Department, Air quality.
    El Amraoui, Laaziz
    Eschbacher, Kurt
    Hirtl, Marcus
    Maurer, Christian
    Mulder, Marie D.
    Piontek, Dennis
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Rokitansky, Carl-Herbert
    Zobl, Fritz
    Zopp, Raimund
    An ensemble of state-of-the-art ash dispersion models: towards probabilistic forecasts to increase the resilience of air traffic against volcanic eruptions2021In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 21, no 10, p. 2973-2992Article in journal (Refereed)
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    An ensemble of state-of-the-art ash dispersion models: towards probabilistic forecasts to increase the resilience of air traffic against volcanic eruptions
  • 27. Politis, K
    et al.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Bayesian updating of atmospheric dispersion after a nuclear accident2004In: The Journal of the Royal Statistical Society, Series C: Applied Statistics, ISSN 0035-9254, E-ISSN 1467-9876, Vol. 53, p. 583-600Article in journal (Refereed)
    Abstract [en]

    We consider a Bayesian forecasting. system to predict the dispersal of contamination on a large scale grid in the event of an accidental release of radioactivity. The statistical model is built on a physical model for atmospheric dispersion and transport called MATCH. Our spatiotemporal model is a dynamic linear model where the state parameters are the (essentially, deterministic) predictions of MATCH; the distributions of these are updated sequentially in the light of monitoring data. One of the distinguishing features of the model is that the number of these parameters is very large (typically several hundreds of thousands) and we discuss practical issues arising in its implementation as a realtime model. Our procedures have been checked against a variational approach which is used widely in the atmospheric sciences. The results of the model are applied to test data from a tracer experiment.

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

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

  • 29.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Extended back-trajectories by means of adjoint equations2004Report (Other academic)
    Abstract [en]

    Back-trajectory models are examples of the most simple adjoint models used for tracing of important source regions attributed to measured tracers. These models do, however, suffer from oversimplification of the transport-diffusion processes in the atmosphere. By utilizing adjoint equations in a 3D transport-diffusion model several advantages could be achieved, all transport mechanisms are included and the response at receptor points could more properly mimic the sampled time-period of the measurements. In this paper the concept of adjoint equations is described, the similarity between back-trajectories and the adjoint technique is demonstrated, and options of using the ad joint technique for guidance of emission sources are explored. To illustrate the possibilities four different events are examined, the Chernobyl accident, the ETEX I exercise, the Algeciras accident and an event with heavy smoke noticed in Scandinavia. Finally, a suggestion for an operational setup is discussed.

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  • 30.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Koncentrations- och depositionsberäkningar för en sopförbrännings anläggning vid Ryaverken i Borås1986Report (Other academic)
  • 31.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Koncentrations- och depositionsberäkningar för Halmstads avfallsförbränningsanläggning vid Kristinehed1986Report (Other academic)
  • 32.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Modelling of anthropogenic sulfur deposition to the African and South American continents1996Report (Other academic)
    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 Africa and South America, using emission data for 1987. The calculations indicate that the anthropogenic perturbation of the sulfur deposition exceeds 100 mg S m-2yr-1 for southern Africa, areas around the Red Sea, Caribbean Islands, northernmost South America, central Andes, and the eastern parts of Brazil and Argentina. Substantial areas around the major source regions receive more than 250 mg S m-2yr-1. Even higher values are calculated for areas surrounding large cities as Carracas, Lima, Rio de Janeiro and Sao Paulo, Pretoria and around the borderline between Zaire and Zambia.

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  • 33.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridningsberäkningar för Varbergs kommun: Bestämning av halter av SO2, CO, NOx samt några kolväten1987Report (Other academic)
  • 34.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridningsberäkningar rörande gasutsläpp vid ScanDust i Landskrona – bestämning av cyanvätehalter1986Report (Other academic)
  • 35.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Spridningsberäkningar rörande utsläpp av NOx inom Fagersta kommun1986Report (Other academic)
  • 36.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Source function estimate by means of variational data assimilation applied to the ETEX-I tracer experiment1998In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 32, no 24, p. 4219-4225Article in journal (Refereed)
    Abstract [en]

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

  • 37.
    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.

  • 38.
    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.

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  • 39.
    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.

  • 40.
    Robertson, Lennart
    et al.
    SMHI, Research Department, Air quality.
    Ring, Sture
    SMHI, Professional Services.
    Spridningsberäkningar för bromcyan2009Report (Other academic)
  • 41.
    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.

  • 42. 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)
  • 43. 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.

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  • 44. 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
  • 45.
    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)
  • 46.
    Wern, Lennart
    et al.
    SMHI, Core Services.
    Kindell, Sven
    SMHI, Professional Services.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Luktberäkningar för AB ELMO i Flen1986Report (Other academic)
  • 47. Zunckel, M
    et al.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Tyson, P D
    Rodhe, H
    Modelled transport and deposition of sulphur over Southern Africa2000In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 34, no 17, p. 2797-2808Article in journal (Refereed)
    Abstract [en]

    Ambient SO2 concentrations and atmospheric deposition of sulphur resulting from emissions on the industrialised highveld region of South Africa are estimated using the multi-scale atmospheric transport and chemistry (MATCH) modelling system, developed at the Swedish Meteorological and Hydrological Institute (SMHI), and compared with an inferential model driven by measured input quantities. Modelled SO, concentrations on the central highveld mostly range between 10 and 50 ppb, exceeding 50 ppb in source areas. Dry deposition rates for sulphur exhibit a similar spatial pattern to the ambient SO2 concentrations and both are consistent with synoptic-scale transport patterns. Maximum dry deposition rates for sulphur of more than 10 kg S ha(-1) a(-1) occur over the central highveld with a well-defined gradient decreasing away from the source region. Despite the significant differences in modelling approaches, the estimates of dry deposition provided by MATCH are in reasonable agreement with those of the inferential model. The maximum modelled wet deposition rates occur over the South African highveld and its periphery and range between 1 and 5 kg S ha(-1) a(-1) and compare favourably with measurements from an acid rain network. Wet deposition generally exceed dry deposition on the highveld and the adjacent areas except in the central highveld source region. Over the drier western half of South Africa MATCH-modelled dry and wet deposition rates are again similar and are less that 1 kg S ha(-1) a(-1). Wet deposition exceeds dry in the higher rainfall regions along the south and east coasts of South Africa. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.

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