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  • 1. Heinemann, G
    et al.
    Klein, Thomas
    SMHI, Core Services.
    Modelling and observations of the katabatic flow dynamics over Greenland2002In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 54, no 5, p. 542-554Article in journal (Refereed)
    Abstract [en]

    The katabatic wind system over the Greenland ice sheet is studied using simulations of the hydrostatic Norwegian Limited Area Model (NORLAM) and measurements of an instrumented aircraft. The structure and the dynamics of the katabatic wind over the ice sheet are investigated for a case study of the aircraft-based experiment KABEG (Katabatic wind and boundary layer front experiment around Greenland) in the area of southern Greenland in April/May 1997. Monthly mean Structures and individual contributions of the momentum budget integrated over the boundary layer are examined for one winter month. The NORLAM is able to simulate realistically the Structures of the katabatic wind system in the lowest 400 in. The comparison with KABEG aircraft measurements for a katabatic wind case with strong synoptic forcing shows good agreement for the momentum budget terms. The pure katabatic force represents the main mechanism for the boundary layer wind field. but a considerable influence of the large-scale synoptic forcing is found as well. Acceleration components from the NORLAM forecasts are also presented for the whole month of January 1990. The monthly mean fields show significant regional differences because of different inversion strengths and synoptic forcings. In particular. Southeast Greenland is influenced by transient synoptic cyclones and the associated cloud patterns. All other areas of the slopes of the Greenland ice sheet are characterized by a downslope katabatic acceleration. The pressure gradient force over the northwestern part of the Greenland ice sheet points in the direction of the local katabatic force, which explains the relatively strong monthly mean near surface winds over the ice. Over the southwestern and northeastern parts of Greenland, however, no significant synoptic support of the katabatic winds is present, and the synoptic pressure gradient is even opposed to the katabatic force in some regions.

  • 2.
    Klein, Thomas
    et al.
    SMHI, Core Services.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Parameterization of dry deposition in MATCH2002Report (Other academic)
    Abstract [en]

    The present report describes the calculation of dry deposition in the Multi scale Atmospheric Transport and Chemistry modeling system (MATCH) applied in environmental monitoring studies. For this type of applications dry deposition is parameterized by means of a resistance concept. Modeled dry deposition velocities for different surface types, a variety of meteorological conditions and several chemical species are presented. The deposition’s dependence on the individual partial resistances and their variation with the meteorological conditions are illustrated by means of time-series. The details of the resistance concept are discussed in a pedagogical way in order to both facilitate understanding and to point out different deposition paths.Sensitivity studies have been performed for the laminar sub-layer resistance of particles for which two different settings of resistance values are compared. The importance of SO2 and NO2 uptake by the stomata of plants and the deposition of SO2 to the external parts of plants have also been investigated by means of sensitivity studies. In addition, horizontal maps and monthly mean values of dry deposition velocities based on meteorological data for 1998 are presented.

  • 3.
    Klein, Thomas
    et al.
    SMHI, Core Services.
    Karlsson, Per-Erik
    IVL Swedish Environmental Research Institute.
    Andersson, Stefan
    SMHI, Research Department, Air quality.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Sjöberg, Karin
    IVL Swedish Environmental Research Institute.
    Assessing and improving the Swedish forecast and information capabilities for ground-level ozone2011Report (Other academic)
    Abstract [en]

    This study aims to assess and improve the Swedish forecast and information capabilities for ground-level ozone concentrations in ambient air. The assessment is based on a set of archived results from the Swedish operational chemical transport model MATCH and Swedish in-situ measurements of ozone covering the period of May 2008 to November 2010. The evaluation comprises two major activities: The first activity is an analysis of the overall model performance using standard statistical metrics suitable for longer time series. The second evaluation activity comprises in-detail analyses of the specific ozone episodes occurring in Sweden during the study period. In addition, trajectory modelling is used to investigate the meteorological conditions and transport patterns associated with those episodes. The evaluation of the model results shows that the model scores well according to standard evaluation criteria and confirms results of other studies in that the model easily meets the data quality requirements of the EU air quality directive 2008/50/EC. However, from an operational forecasting and information perspective it would be desirable to further improve the prediction of, in particular, high-level ozone episodes. Two different activities in our study are dedicated to the task of improving the forecast and information capabilities: The first activity tests the usefulness of statistical postprocessing of model results using regression techniques. The tests show promising results although the model performance during high-level ozone episodes is not improved. A limitation of our study is the relatively small archive of model data available for calibration andevaluation. Adaptive post-processing methods have not been tested in our study. The second activity aimed to improve ozone forecasting is a high-resolution model run for the year 2010. The higher reso-lution run gives slightly better results than the coarser operational model, which can be attributed to a better resolution of the physiography and thus certain physical and chemical processes. In particular, high-resolution simulations provide a more realisticrepresentation of the spatial ozone variation which is desirable for environmental assessments with a longer time horizon. However, from the perspective of operational ozone forecasting the increase in resolution cannot correct systematic problems such as an under-prediction of ozone if the source of ozone is non-local and the long-range transboundary transport is not correctly described by the European-scale model used as boundaries. Other potential sources of error are incomplete or erroneous emissions, representativeness issues, oversimplifications in the model’s physical or chemical processes, lacking data assimilation and initialization and oversimplifiedboundary conditions. While several of these issues are already addressed in current initiatives such as the EU FP7-project MACC, it is clear that further work will be needed during the coming years. Further work should also be invested in a better exploitation of the international developments within MACC and in the establishment of operational high-resolution air quality forecasts for Sweden, using boundary values from European-scale forecasts provided by theMACC-ensemble of regional air quality models.

  • 4.
    Klein, Thomas
    et al.
    SMHI, Core Services.
    Kukkonen, Jaakko
    Dahl, Aslog
    Bossioli, Elissavet
    Baklanov, Alexander
    Vik, Aasmund Fahre
    Agnew, Paul
    Karatzas, Kostas D.
    Sofiev, Mikhail
    Interactions of Physical, Chemical, and Biological Weather Calling for an Integrated Approach to Assessment, Forecasting, and Communication of Air Quality2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 8, p. 851-864Article, review/survey (Refereed)
    Abstract [en]

    This article reviews interactions and health impacts of physical, chemical, and biological weather. Interactions and synergistic effects between the three types of weather call for integrated assessment, forecasting, and communication of air quality. Today's air quality legislation falls short of addressing air quality degradation by biological weather, despite increasing evidence for the feasibility of both mitigation and adaptation policy options. In comparison with the existing capabilities for physical and chemical weather, the monitoring of biological weather is lacking stable operational agreements and resources. Furthermore, integrated effects of physical, chemical, and biological weather suggest a critical review of air quality management practices. Additional research is required to improve the coupled modeling of physical, chemical, and biological weather as well as the assessment and communication of integrated air quality. Findings from several recent COST Actions underline the importance of an increased dialog between scientists from the fields of meteorology, air quality, aerobiology, health, and policy makers.

  • 5.
    Klein, Thomas
    et al.
    SMHI, Core Services.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Frankenberg, Britt
    SMHI, Core Services.
    Svensson, J
    SMHI.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    ECDS - a Swedish Research Infrastructure for the Open Sharing of Environment and Climate Data2013In: Data Science Journal, ISSN 1683-1470, E-ISSN 1683-1470, no 12, p. 1-9Article in journal (Refereed)
  • 6. Kukkonen, J.
    et al.
    Olsson, T.
    Schultz, D. M.
    Baklanov, A.
    Klein, Thomas
    SMHI, Core Services.
    Miranda, A. I.
    Monteiro, A.
    Hirtl, M.
    Tarvainen, V.
    Boy, M.
    Peuch, V. -H
    Poupkou, A.
    Kioutsioukis, I.
    Finardi, S.
    Sofiev, M.
    Sokhi, R.
    Lehtinen, K. E. J.
    Karatzas, K.
    San Jose, R.
    Astitha, M.
    Kallos, G.
    Schaap, M.
    Reimer, E.
    Jakobs, H.
    Eben, K.
    A review of operational, regional-scale, chemical weather forecasting models in Europe2012In: Atmospheric Chemistry And Physics, ISSN 1680-7316, E-ISSN 1680-7324, Vol. 12, no 1, p. 1-87Article in journal (Refereed)
    Abstract [en]

    Numerical models that combine weather forecasting and atmospheric chemistry are here referred to as chemical weather forecasting models. Eighteen operational chemical weather forecasting models on regional and continental scales in Europe are described and compared in this article. Topics discussed in this article include how weather forecasting and atmospheric chemistry models are integrated into chemical weather forecasting systems, how physical processes are incorporated into the models through parameterization schemes, how the model architecture affects the predicted variables, and how air chemistry and aerosol processes are formulated. In addition, we discuss sensitivity analysis and evaluation of the models, user operational requirements, such as model availability and documentation, and output availability and dissemination. In this manner, this article allows for the evaluation of the relative strengths and weaknesses of the various modelling systems and modelling approaches. Finally, this article highlights the most prominent gaps of knowledge for chemical weather forecasting models and suggests potential priorities for future research directions, for the following selected focus areas: emission inventories, the integration of numerical weather prediction and atmospheric chemical transport models, boundary conditions and nesting of models, data assimilation of the various chemical species, improved understanding and parameterization of physical processes, better evaluation of models against data and the construction of model ensembles.

  • 7.
    Langner, Joakim
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Klein, Thomas
    SMHI, Core Services.
    Skagerström, M.
    SMHI.
    Nuläge och scenarier för inverkan på marknära ozon av emissioner från Västra Götalands län - Beräkningar för 19992004Report (Other academic)
    Abstract [sv]

    SMHI har på uppdrag av Länsstyrelsen i Västra Götalands län studerat hur olikascenarier för reducerade NOx och VOC-utsläpp från Västra Götaland påverkarfördelningen av marknära ozon över södra Sverige. Studien har utnyttjat den atmosfärkemiskaspridningsmodellen MATCH (Multi-scale Atmospheric Transportand Chemistry model). Modellen har först applicerats över hela Europa förår 1999 med aktuella emissioner. Resultaten från dessa beräkningar har sedankopplats till en högupplöst modell, MATCH-O-län, som täcker södra Sverige.Beräkningar med MATCH har genomförts för ett nuläge (basfall) med utsläppsdataför år 2000/2001 och tre scenarier där utsläppen har reducerats. Scenariermed reduktion av NOx och VOC-utsläppen från Västra Götalands län med 45 respektive44% var för sig respektive sammantaget har studerats. För basfallet harjämförelser gjorts med mätningar av marknära ozon i området för år 1999. Medutgångspunkt från dessa jämförelser bedömer vi att MATCH ger en tillräckligtgod beskrivning av de verkliga ozonhalterna för att kunna utnyttjas för studier avscenarier.Beräkningarna visar att utsläppen från Västra Götaland har en signifikant påverkanpå halterna av marknära ozon i södra Sverige. Reducerade utsläpp leder generellttill reducerade halter av marknära ozon i södra Sverige och lägre värdenför olika mått på kritiska nivåer av halten av marknära ozon. Effekterna av reduceradeutsläpp berör inte bara närområdet utan täcker ett område som är fleragånger större än det område där utsläppen har ändrats.I området närmast Göteborg leder emellertid reducerade NOx-utsläpp till ökadehalter av ozon. Denna effekt är mindre vid en samtidig reduktion av NOx ochVOC.Bortsett från området med stora NOx-utsläpp i västra delen av Västra Götalandså är reduktioner av NOx effektivare när det gäller att reducera halterna av marknäraozon än reduktion av VOC-utsläpp. Reduktion av NOx-utsläpp är mer änsju gånger effektivare än reduktion av VOC-utsläpp när det gäller att reducerabildningen av ozon inom modellområdet för MATCH-O-län under periodenapril-september 1999.Reducerade utsläpp av NOx och VOC från Västra Götaland beräknas, i större delenav länet, leda till en viss minskning av antalet dagar med 8-timmars medelhaltersom överskrider 120 μg/m3 (60 ppb(v)) under sommarperioden aprilseptember.Reducerad NOx-utsläpp förväntas dock leda till ett ökat antal dagarmed överskridanden i Göteborgsområdet.Reducerade utsläpp från Västra Götaland leder till en reduktion av AOT401 med0.1 ppm(v) h över en stor del av södra Sverige under perioden maj-juli. Den2maximala reduktionen överstiger 0.5 ppm(v) i enstaka beräkningsrutor. För periodenapril-september reduceras AOT40 med mer än 0.1 ppm(v) h i en större delav södra Sverige och en reduktion med mer än 0.5 ppm(v) h beräknas för en stordel av Västra Götaland.

  • 8.
    Persson, Christer
    et al.
    SMHI, Research Department, Air quality.
    Ressner, Elisabet
    SMHI.
    Klein, Thomas
    SMHI, Core Services.
    Nationell miljöövervakning – MATCH-Sverige modellen: Metod- och resultatsammanställning för åren 1999-2002 samt diskussionav osäkerheter, trender och miljömål2004Report (Other academic)
    Abstract [en]

    National air pollution assessments based on the MATCH-Sweden model – Results for the period 1999-2002 The MATCH-Sweden model system is used as a tool for mapping of air pollution deposition and concentration over Sweden and for air pollution assessment studies.The system includes a simplified type of data assimilation of backgroundatmospheric chemistry observations in Sweden and Norway. Over the entire period 1999-2002 the annual sulphur and nitrogen deposition consistently shows a maximum over Southwest Götaland and decreases northwards. An annual air pollution budget for Sweden is determined. During the period of study the Swedish emissions account for 5-7% of the total annual deposition of sulphur in Sweden and for 11-13% of the corresponding NOx-deposition. The Swedish contribution to the total deposition of NHx-nitrogen is, according to the present calculations, about 16%. However, the uncertainty in this value is larger than for sulphur and NOx-nitrogen.Comparisons between results for the year 2000 obtained with MATCH-Sweden and the new “Unified EMEP Eulerian model” (EMEP, 2003) respectively, show good agreement for most parameters. The agreement is much better than observed in earlier comparisons with the old EMEP model. Large differences are found only for long-range transport contribution to the NHx-deposition over Northern Sweden, where MATCH-Sweden calculations indicate larger depositions than EMEP. However, the MATCH-Sweden system – including simplified data assimilation - suffers from a lack of representative air and precipitation NHx-measurements in that area. A tentative estimate of deposition trends over Sweden indicates a 50-55% decrease for sulphur between 1991 and 2002. For NOx- and NHx-nitrogen the corresponding decrease in deposition is only about 15%each.

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