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  • 51.
    Kjellström, Erik
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Gollvik, Stefan
    Meterologi.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Wyser, Klaus
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    A 140-year simulation of European climate with the new version of the Rossby Centre regional atmospheric climate model (RCA3)2005Rapport (Annet vitenskapelig)
    Abstract [en]

    This report presents the latest version of the Rossby Centre regional atmospheric model, RCA3, with focus on model improvements since the earlier version, RCA2. The main changes in RCA3 relate to the treatment of land surface processes. Apart from the changes in land surface parameterizations several changes in the calculation of radiation, clouds, condensate and precipitation have been made. The new parameterizations hold a more realistic description of the climate system.Simulated present day climate is evaluated compared to observations. The new model version show equally good, or better, correspondence to observational climatologies as RCA2, when forced by perfect boundary conditions. Seasonal mean temperature errors are generally within ±1oC except during winter in north-western Russia where a larger positive bias is identified. Both the diurnal temperature range and the annual temperature range are found to be underestimated in the model. Precipitation biases are generally smaller than in the corresponding reanalysis data used as boundary conditions, showing the benefit of a higher horizontal resolution.The model is used for the regionalization of two transient global climate change projections for the time period 1961- 2100. The radiative forcing of the climate system is based on observed concentrations of greenhouse gases until 1990 and on the IPCC SRES B2 and A2 emissions scenarios for the remaining time period. Long-term averages as well as measures of the variability around these averages are presented for a number of variables including precipitation and near-surface temperature. It is shown that the changes in variability sometimes differ from the changes in averages. For instance, in north-eastern Europe, the mean increase in wintertime temperatures is followed by an even stronger reduction in the number of very cold days in winter. This kind of performance of the climate system implies that methods of inferring data from climate change projections to other periods than those actually simulated have to be used with care, at least when it comes to variables that are expected to change in a non-linear way. Further, these new regional climate change projections address the whole 21st century.

    Fulltekst (pdf)
    FULLTEXT01
  • 52.
    Klein, Thomas
    et al.
    SMHI, Samhälle och säkerhet.
    Bergström, Robert
    SMHI, Forskningsavdelningen, Luftmiljö.
    Persson, Christer
    SMHI, Forskningsavdelningen, Luftmiljö.
    Parameterization of dry deposition in MATCH2002Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 53.
    Klein, Thomas
    et al.
    SMHI, Samhälle och säkerhet.
    Karlsson, Per-Erik
    IVL Swedish Environmental Research Institute.
    Andersson, Stefan
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    Sjöberg, Karin
    IVL Swedish Environmental Research Institute.
    Assessing and improving the Swedish forecast and information capabilities for ground-level ozone2011Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    FULLTEXT01
  • 54.
    Landelius, Tomas
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Josefsson, Weine
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Persson, Thomas
    SMHI.
    A system for modelling solar radiation parameters with mesoscale spatial resolution2001Rapport (Annet vitenskapelig)
    Abstract [en]

    Today, modern analysis systems synthesise meteorological data from a number of sources, e.g.\ round based SYNOP, satellites, radar, etc., into field information which enable us to model radiation at the Earth’s surface on the mesoscale. At the Swedish Meteorological and Hydrological Institute (SMHI) we have set up a model system that produce hourly information in terms of field data with a resolution of about 22 ´ 22 km2 for a geographic area covering Scandinavia and the run off region of the Baltic sea.Presently, the model calculates fields of global-, photosynthetically active- (PAR), UV- and direct radiation based on output from a mesoscale analysis system, a high resolution limited area numerical weather prediction model (NWP), an ice model for the Baltic sea together with satellite measurements of total ozone. A spectral clear sky model lies at the heart of the model system. Its output is multiplied by a function which captures the influence of clouds and precipitation. Different cloud effect functions are applied to the different radiation components, with the exception of global- and PAR for which the same relation is assumed.Measurements from the radiation network of SMHI were used for estimation and validation purposes. A first evaluation of the model system suggests that the RMSE for hourly global radiation data is on the order of 28% and about 16% for daily values. These errors are comparable to those obtained for models purely based on synoptic observations (SYNOP) (29% and 13%) . For UV radiation the figures are similar but for the direct radiation component they are worse; 53% and 31% respectively compared to 25% and 15% for the SYNOP models. To some extent the larger errors for the direct component could be explained by its sensitivity to scale differences when model grid squares are validated against point measurements.

    Fulltekst (pdf)
    FULLTEXT01
  • 55.
    Langner, Joakim
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Bergström, Robert
    SMHI, Forskningsavdelningen, Luftmiljö.
    Plejel, Karin
    Swedish Environmental Research Institute IVL.
    European scale modeling of sulfur, oxidized nitrogen and photochemial oxidants: Model development and evaluation for the 1994 growing season1998Rapport (Annet vitenskapelig)
    Abstract [en]

    A chemical mechanism, including the relevant reactions leading to the production of ozone and other photochemical oxidants, has been implemented in the MATCH regional tracer transport/chemistry/deposition model. The aim has been to develop a model platform that can be used as a basis for a range of regional scale studies involving atmospheric chemistry, including assessment of the importance of different sources of pollutants to the levels of photochemical oxidants and air pollutant forecasting. Meteorological input data to the model were taken from archived output from the operational version of HIRLAM at SMHI. Evaluation of model calculations over Europe for a six month period in 1994 for a range of chemical components show good results considering known sources of error and uncertainties in input data and model formulation. With limited further work the system is sufficiently good to be applied for scenario studies and for regional scale air pollutant forecasts.

    Fulltekst (pdf)
    fulltext
  • 56.
    Langner, Joakim
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Persson, Christer
    SMHI, Forskningsavdelningen, Luftmiljö.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Air pollution Assessment Study Using the MATCH Modelling System: Application to sulfur and nitrogen compounds over Sweden 19941996Rapport (Annet vitenskapelig)
    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%.

    Fulltekst (pdf)
    fulltext
  • 57.
    Laurin, Sten
    SMHI.
    Population exposure to SO2 and NOx from different sources in Stockholm1984Rapport (Annet vitenskapelig)
    Abstract [en]

    A model for calculation of population exposure to air pollution is developed. With the aid of an existing dispersion model, SO2 and NOx concentrations are calculated in a network of gridpoints covering the Greater Stockholm area. Emissions from traffic and stationary sources are treated in the model. A simple model is constructed in order to improve the population data initially given. It is thereafter possible to take into account exposure at work as welI as at home for the working part of the population.

    Fulltekst (pdf)
    fulltext
  • 58.
    Liljas, Erik
    SMHI, Samhälle och säkerhet.
    Analys av moln och nederbörd genom automatisk klassning av AVHRR-data1981Rapport (Annet vitenskapelig)
    Fulltekst (pdf)
    fulltext
  • 59.
    Lind, Petter
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Temperature and precipitation changes in Sweden; a wide range of model-based projections for the 21st century2008Rapport (Annet vitenskapelig)
    Abstract [en]

    In this report we analyze the climate change signal for Sweden in scenarios for the 21st century in a large number of coupled atmosphere-ocean general circulation models (AOGCMs), used in the fourth assessment report by the Intergovernmental Panel on Climate Change (IPCC). We focus on near-surface temperature and precipitation. The analysis includes six emission scenarios as well as multi-member runs with the AOGCMs. At the Rossby Centre, SMHI, regional climate models have been run under different emission scenarios and driven by a few AOGCMs. The results of those runs have been used as a basis in climate change, impact and adaptation assessments. Here, we evaluate results from these regional climate model runs in relation to the climate change signal of the IPCC AOGCMs. First, simulated conditions for the recent past (1961-1990) are evaluated. Generally, most AOGCMs tend to have a cold bias for Sweden, especially in winter that can be as large as 10°C. Also, the coarse resolution of the AOGCMs leads to biases in simulated precipitation, both in averages, extremes and often also in the phase of the seasonal cycle. Generally, AOGCMs overestimate precipitation in winter; biases reach 30-40% or even more. In summer, some AOGCMs overestimate precipitation while others underestimate it. Projected responses depend on season and geographical region. Largest signals are seen in winter and in northern Sweden, where the mean simulated temperature increase among the AOGCMs (and across the emissions scenarios B1, A1B and A2) is nearly 6°C by the end of the century, and precipitation increases by around 25%. In southern Sweden, corresponding values are around +4°C and +11%. In summer, the temperature increase is more moderate, which is also the case for precipitation. The regional climate signals are usually within the ranges given by the AOGCM runs, however, the regional models tends to show larger increases in winter, and smaller increases in summertime precipitation.

    Fulltekst (pdf)
    FULLTEXT01
  • 60.
    Lundqvist, Jan-Eric
    et al.
    SMHI.
    Udin, Ingemar
    SMHI, Samhälle och säkerhet.
    Ice accretion on ships with special emphasis on Baltic conditions1977Rapport (Annet vitenskapelig)
    Abstract [sv]

    Sedan mitten av 1960-talet har nedisningsrapporter från fartyg som trafikerat Östersjön samlats in av SMHI. Rapporterna har bearbetats och samband mellan nedisning och vissa meteorologiska och oceanografiska parametrar har studerats. Undersökningen har omfattat handelsfartyg av typisk storlek för Östersjön. Rapporten visar resultaten från nedisningskampanjen. Den innehåller dessutom en allmän beskrivning, vilken omfattar faktorer som orsakar nedisning, frysprocessen etc. En del tidigare arbeten har studerats och jämförelser av resultat har gjorts. Nedisningsprognoser diskuteras och den metod som nu används vid SMHI beskrivs. Slutligen ges en del kommentarer om metoder att undvika eller minska nedisning.

    Fulltekst (pdf)
    fulltext
  • 61.
    Lönnqvist., Olov
    SMHI.
    Congression – A fast regression technique with a great number of functions of all predictors1984Rapport (Annet vitenskapelig)
    Abstract [en]

    The term Congression is used for an entirely new technique for Multiple Regression Analysis. The merits of the new technique are obvious. It is made possible to introduce a vast number of derived predictors in the analysis without prolonging the computing time.

    In the examples given in the paper, 6 predictors are increased to 1068, and the analysis carried out in less than 25 per cent of the time now needed for 6 predictors.

    The main features of Congression are the Grouping of data in Parties and the use of Grouping Diagrams as an interface towards a great number of pre-prepared. Potential functions of any two predictors; xi2, xixj, sin x1 and V xi2 + xj2 , are examples of such functions.

    Fulltekst (pdf)
    fulltext
  • 62.
    Lönnqvist., Olov
    SMHI.
    Nederbördsstatistik med praktiska tillämpningar: Precipitation statistics with practical applications1981Rapport (Annet vitenskapelig)
    Abstract [en]

    Precipitation statistics for Sweden are presented in a very special way in order to serve as a planning tool in the Weather Service. Empirical Orthogonal Functions for the precipitation based on monthly normals for 643 stations, 1931-1960, are applied to two practical design problems, viz. geographical areas for weather forecasting and the network of synoptic stations. The paper also deals with maritime and continental areas of Sweden. The representativity of results obtained is judged by a sample af precipitation data for the last 100 years.A discussion is given as to the usefulness of the climatological method for the actual aoplication purposes as compared with correlation af time-series of precipiation and other weather parameters.

    Fulltekst (pdf)
    fulltext
  • 63.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    The first Rossby Centre regional climate scenario for the Baltic Sea using a 3D coupled ice-ocean model2001Rapport (Annet vitenskapelig)
    Abstract [en]

    Temperature, salinity, sea ice and sea leve! in the Baltic Sea have been analyzed under different climate conditions using a 3D coupled ice-ocean mode!. As a reference, hindcast simulations for the period 1980-93 have been performed with observed three-hourly meteorological forcing fields and observed monthly river runoff. The observed Baltic Sea climate is well  reproduced by the mode!. Furthermore, two sets of 9-year time slice experiments have been performed using results of an atmospheric regional climate mode! as forcing, one representing pre-industrial climate conditions (control simulation), and the other one global waiming with a 150% increase of CO2 greenhouse gas concentration (scenario simulation). At the boundaries of the regional climate mode! results of the global atmosphere-ocean general circulation mode! HadCM2 (Hadley Centre) have been prescribed. To simulate river runoff, a large-scale hydrological mode! has been applied. As the time slices are too short to spin up initial stratification for future climate, salinity is treated as uncertainty. An extreme condition is obtained, integrating the Baltic Sea model for 100 years assuming that no salt water inflow occurs in future. The area averaged annual mean sea surface temperature change between scenario and control run is about 2.3 'C. Seasonal variability of the change is small compared to the corresponding 2 m air temperature change. The uncertainty due to unknown future initial conditions is relatively small (largest in summer with -0.5'C). The decrease of mean ice extent in the scenario compared to the control run is dramatic, from 210 • 109m2 to 82 • 109m2 (a relative change of 61 % ). However, in all years ice can still be found in the Bothnian Bay. The minimum ice extent is I 6 • 109m2 (for comparison: the area of the Bothnian Bay is about twice as !arge). The mean number of ice days decreases significantly, too. In the fast ice zone of the Bothnian Bay (Kemi) the mean ice season becomes 40 days shorter. The ice in the scenario run is thinner with less snow on top. In the·central Bothnian Bay mean maximum annual ice thickness is reduced by 25 cm from 54 to 29 cm. Mode! dependent uncertainties are discussed.

    Fulltekst (pdf)
    fulltext
  • 64.
    Meier, Markus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Andréasson, Johan
    SMHI, Affärsverksamhet.
    Broman, Barry
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Persson, Gunn
    SMHI, Affärsverksamhet.
    Climate change scenario simulations of wind, sea level, and river discharge in the Baltic Sea and Lake Mälaren region – a dynamical downscaling approach from global to local scales2006Rapport (Annet vitenskapelig)
    Abstract [en]

    A regional climate model (RCM) and oceanographic, hydrological and digital elevation models were applied to study the impact of climate change on surface wind, sea level, river discharge, and flood prone areas in the Baltic Sea region. The RCM was driven by two global models and two emission scenarios. According to the four investigated regional scenario simulations, wind speed in winter is projected to increase between 3 and 19% as an area average over the Baltic Sea. Although extremes of the wind speed will increase about as much as the mean wind speed, sea level extremes will increase more than the mean sea level, especially along the eastern Baltic coasts. In these areas projected storm events and global average sea level rise may cause an increased risk for flooding. However, the Swedish east coast will be less affected because mainly the west wind component in winter would increase and because land uplift would compensate for increased sea levels, at least in the northern parts of the Baltic. One of the aims of the downscaling approach was to investigate the future risk of flooding in the Lake Mälaren region including Stockholm city. In Stockholm the 100-year surge is projected to change between -51 and 53 cm relative to present mean sea level suggesting that in the city the risk of flooding from the Baltic Sea is relatively small because the critical height of the jetty walls will not be exceeded. Lake Mälaren lies just to the west of Stockholm and flows directly into the Baltic Sea to the east. This study addresses also the question of how the water level in Lake Mälaren may be affected by climate change by incorporating the following three contributing components into an analysis: 1) projected changes to hydrological inflows to Lake Mälaren, 2) changes to downstream water levels in the Baltic Sea, and 3) changes in outflow regulation from the lake. The first component is analyzed using hydrological modeling. The second and third components employ the use of a lake discharge model. An important conclusion is that projected changes to hydrological inflows show a stronger impact on lake levels than projected changes in water level for the Baltic Sea. Furthermore, an identified need for increased outflow capacity from the lake for the present climate does not diminish with projections of future climate change. The tools developed in this work provide valuable inputs to planning for both present and future operations of water level in Lake Mälaren. Based on the oceanographic and hydrological scenario simulations, flood prone areas were analysed in detail for two municipalities, namely Ekerö and Stockholm. The GIS analysis of both municipalities indicates a series of affected areas. However, in case of the 100-year flood (0.65 m above the mean lake level) in present climate or even in case of the maximum probable flood (1.48 m above the mean lake level) the potential risks will be relatively low.

    Fulltekst (pdf)
    FULLTEXT01
  • 65.
    Melgarejo, José
    SMHI.
    An analytical model of the boundary layer above sloping terrain with an application to observations in Antarctica1986Rapport (Annet vitenskapelig)
    Abstract [en]

    Analytical solutions of a set of equations that couples the Ekman and the Prandtl boundary layer (BL) equations were obtained; closure on the subgrid scale was via the eddy exchange (K) approach, where K was made to depend on both the internal stability (μ) and height raised to an arbitrary power. The boundary layer height (h) wis also made to depend on μs. As byproducts of these solutions, generalized expressions for the universal functions of μ, A, B and C and for the resistance and heat-transfer laws (i. e. a, u*/G ind T*/0, respectively) for a given set of external parameters (X, Ro and S) for the general case of the slope angle 0~~~10 rad were presented. From this, an interesting and novel result is the finding that there are three different regimes of solutions depending on whether S (or ~) is less than, equal to or greater than certain critical value S (or ~ ). The solutions for all three regimes were presented in graphical form, from which the appreciable influence of terrain slope on the cross-isobaric inflow angle, the momentum- and heat-transfer is clearly discernible. Also in a preliminary test of the results of this investigation with observations, it is found that the theoretical values of the cross-isobaric angle are in good agreement with the observed values in Antarctica and therefore encouraging for further research.

    Fulltekst (pdf)
    fulltext
  • 66.
    Melgarejo, José
    SMHI.
    Similarity theory and resistance laws for the atmospheric boundary layer1981Rapport (Annet vitenskapelig)
    Abstract [en]

    The theory of the boundary layer above a therrmally active inclined terrain, in which the actual height h of the boundary layer is used as length scale, is presented. Analytical solutions for the mean wind and temperature structures are obtained. These solutions are seen to depend on the non-dimensional parameters h/L, A = hs /ys, h/zo , the slope angle u the direction of the geostrophic wind x in addition to z/h. As by-products of these solutions (1) expressions for the similarity theory stability functions a, b and c are obtained which are in agreement with the theoretical expressions of Zilitinkevichand Brost and Wyngaard (2). For slope angles much less than 0.01, u = 0 yields the well-known expressions of Zilitinkevich and Deardorff. The appreciable influence of u and x on the geostrophic drag coefficient and on the crossisobaric angle a is assessed and and presented in graphical form. Finally, a preliminary test which shows that the predicted a is in satisfactory agreement with observations, is also presented.

    Fulltekst (pdf)
    fulltext
  • 67.
    Meuller, Lars
    et al.
    SMHI.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Andersson, Erik
    SMHI.
    Gustavsson, Nils
    Meterologi.
    Meso-g scale objective analysis of near surface temperature, humidity and wind, and its application in air pollution modelling1990Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    fulltext
  • 68.
    Michelson, Daniel
    et al.
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Andersson, Tage
    SMHI, Forskningsavdelningen.
    Koistinen, Jarmo
    FMI.
    Collier, Christopher G.
    University of Salford.
    Riedl, J.
    German Weather Service.
    Szturc., J.
    Institute of Meteorology and Water Management.
    Gjertsen, Uta
    The Norwegian Meteorological lnstitute.
    Nielsen, Aage
    Danish Meteorological lnstitute.
    Overgaard,, Soeren
    Danish Meteorological lnstitute.
    BALTEX Radar Data Centre Products and their Methodologies2000Rapport (Annet vitenskapelig)
    Abstract [en]

    The Baltic Sea Experiment (BALTEX) is the European regional project within the Global Energy and Water Cycle Experiment (GEWEX). The BALTEX Working Group on Radar (WGR) is responsible for coordinating weather radar activities within the framework of BALTEX, including the establishment and operation of a Radar Data Centre (BRDC) which can provide BALTEX with wind and precipitation datasets. This report presents the state of the WGR and the BALTEX Radar Network (BALTRAD). Those products being generated at the BRDC are presented and discussed, as are the methods used to create them.

    The BALTRAD network consists of 29, mostly C-band, radars in six countries. Communications to/from the BRDC are conducted both through operational lines and through provisional lnternetbased solutions. The BRDC operates in near-real time. Individual radar images containing radar reflectivity factor (dBZ) are produced with a temporal resolution of 15 min. These are combined to create composite images, also every 15 minutes. A systematic gauge correction method is introduced for application to point observations from the synoptical network. These corrected gauge observations are used together with radar sums to create spatially continuous, gauge-adjusted threeand twelve-hour accumulations. The gauge adjustment technique is shown to minimize the bias between radar and gauge observations, while also reducing the range dependency on the radar data. All image products have horizontal resolutions of 2 km. A wind profile product is also created using VAD and VVP techniques.

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  • 69.
    Moen, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    A multi-level quasi-geostrophic model for short range weather predictions1975Rapport (Annet vitenskapelig)
    Abstract [en]

    A quite generally formulated multilevel quasi-geostrophic medel with possibilities to include second order terms in the vorticity equation is derived. The model includes friction, topography, latent heat and sensible heat. The treatment of the variable boundary conditions, smoothing and ellipticity control is described.

    Fulltekst (pdf)
    fulltext
  • 70.
    Nyberg, Anders
    SMHI.
    On transport of sulphur over the North Atlantic1976Rapport (Annet vitenskapelig)
    Abstract [sv]

    Svavelinnehållet i nederbörden har uppmätts på väderskepp i Nordatlanten. På grundval härav och av trajektorieberäkningar visas att betydande mängder antropogent svavel transporteras från Nordamerika mot Europa. Torrdepositionen av svavel över Atlanten på långa avstånd från källan måste vara mycket liten. Värdena på nederbördsutfallet av svavel ur luft som kommer från det azoriska högtrycksområdet är mycket låga och man kan därför säga att det naturliga svavlet i nederbörd i allmänhet högst är av storleksordningen  0 .0 mg/1.

    Fulltekst (pdf)
    fulltext
  • 71.
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    A sensitivity analysis of steady, free floating ice1980Rapport (Annet vitenskapelig)
    Abstract [sv]

    Ekvationen för stationär, friflytande is härleds och analyseras för ett grunt hav. Analysen behandlar hur noggrant den stationära, friflytande isens rörelse kan beräknas då variationer införs i ingångsparametrarna. Förutom fel på grund av icke perfekta vindar, orsakar områden med starka strömmar dålig noggrannhet. Om dessutom bottendjupet försummas i dessa områden blir noggrannheten sämre. Varierande isskrovlighet och varierande friktionshastighet medför fel som är mindre viktiga men ändock märkbara i den beräknade ishastigheten.

    Fulltekst (pdf)
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  • 72.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Sahlberg, Jörgen
    SMHI, Affärsverksamhet.
    Some results from a joint Swedish-Finnish sea ice experiment, March, 19771978Rapport (Annet vitenskapelig)
    Abstract [sv]

    Ett gemensamt svensk-finskt havsisexperiment genomfördes under mars 1977. Mätningar i atmosfären, isen och havet utfördes under sex dagar ombord på det finska forskningsfartyget Aranda som var placerad i isfältet i Bottenviken. Under två dagar utfördes även mätningar från de två svenska isbrytarna Atle och Tor. Denna rapport presenterar data och några resultat från svenska gruppen.

    Fulltekst (pdf)
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  • 73.
    Omstedt, Gunnar
    SMHI, Forskningsavdelningen, Luftmiljö.
    An operational air pollution model1988Rapport (Annet vitenskapelig)
    Abstract [en]

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

    Fulltekst (pdf)
    fulltext
  • 74.
    Omstedt, Gunnar
    SMHI, Forskningsavdelningen, Luftmiljö.
    An operational air pollution model using routine meteorological data1984Rapport (Annet vitenskapelig)
    Abstract [en]

    An operational air pollution model using routine meteorological data is described. An hourly time series of pollutant concentrations is calculated for emissions from one or several tall industrial stacks. New methods developed by Nielsen et al. (1981),. Berkowicz and Prahm (1982 a, b), Olesen et al.(1983) are used for determining boundary layer parameters i.e. surface sensible heat flux, friction velocity, mean wind speed and mixing height. These parameter values are used as input data to the dispersion part of the model. An updated Gaussian dispersion model, strongly supported by experimental data and similar to that developed by Weil and Bower (1982) is used. Briggs' dispersion parameters are used with the stability classification scheme based on the values of w*/u during daytime and Pasquill-Gifford-Turner classes during nighttime for selection of stability classes. Plume rise and plume penetration of elevated stable layers are calculated by formulae from Briggs (1975). A similar model will also be used in Denmark (Berkowicz et al., 1983). Examples of results are given, based on four years of hourly meteorological data and radiosonde data from Bromma airport in Stockholm. A tentative comparison between the present model and Högström's (1968) model is made for emission from a 500 MW power plant. This comparison indicates that Högström's model predicts ground level concentrations that are too high occurring too close to tall industrial stacks.

    Fulltekst (pdf)
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  • 75.
    Omstedt, Gunnar
    SMHI, Forskningsavdelningen, Luftmiljö.
    Spridning av luftförorening från skorsten i konvektiva gränsskikt1982Rapport (Annet vitenskapelig)
    Abstract [sv]

    Målsättningen för detta arbete har varit att formulera en bra men enkel modell för luftföroreningsspridning från skorstenar vid konvektiva meteorologiska förhållanden. Olika modeller diskuteras i rapporten. Den som väljs är den Gaussiska modellen med plymlyftsformler enligt Weil (1980). Ett huvudproblem vid spridningsberäkningar är att välja spridningsparametrar. Det finns ett flertal olika empiriska och teoretiska metoder, som ger betydande skillnader som resultat. En praktisk infallsvinkel har här valts: Om en Gaussisk spridningsmodell utnyttjas, vilka värden på spridningsparametrarna skall då väljas? Olika formuleringar har testats mot mätdata från några olika anläggningar i USA. Resultaten från beräkningarna visar att bäst överensstämmelse mellan beräknade och uppmätta markhalter av so2 erhålles med empiriska spridningsparametrar från Brookhaven National Laboratory, ett resultat som är i överensstämmelse med arbeten av Weil (1977, 1979a, b och 1980). Beräknade halter är i 14 fall av 15 inom en faktor två av uppmätta halter. Beräkningar med teoretiskt bestämda spridningsparametrar för värmepassiva partiklar (Lamb, 1981) ger i 8 fall av 12 för låga halter. En mer realistisk formulering, där beskrivning av plymens egenspridning ingår, förbättrar inte resultaten på något avgörande sätt. Detta tyder på att direkt hänsyn måste tas till plymaxelns nedåtgående rörelse, som är känd att inträffa vid konvektiva förhållanden, vid utnyttjande av teoretiskt bestämda spridningsparametrar. Beräkningar har också utförts med SMHis nuvarande spridningsmodeller.

    Fulltekst (pdf)
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  • 76.
    Omstedt, Gunnar
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Szegö, Janos
    Boverket.
    Människors exponering för luftföroreningar1990Rapport (Annet vitenskapelig)
    Abstract [en]

    This report describes a model for calculation of human exposure to air pollution. The model consist of two parts. In the first part air pollution concentrations are calculated, as function of space and time, by using an air pollution model (Omstedt, 1988, Robertson, 1989). Inputdata are routine meteorological data, emission data and background air pollution data.

    In the second part of the model the population dynamics in cities are described by using detailed statistical data for the day- and nighttime populations, according to Szegö (1974, 1987).

    The model is illustrated by two cases, Helsingborg and Örebro. The results are compared with exposure calculations from simplified methods.

    Fulltekst (pdf)
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  • 77.
    Pershagen, H.
    SMHI.
    Maximisnödjup i Sverige (perioden 1905–70)1981Rapport (Annet vitenskapelig)
    Abstract [en]

    Data have been obtained from 40 selected meteorological stations.The following monthly tables have been prepared:

    A Various statistical information in cm.B The five highest and lowest values with year of occurrence.C Relative frequency.D Classification of the depth of snow.E The five mast and least severe snow-seasons for each station.F The five mast and least severe snow-seasons in certain regions.G The five mast and least severe snow-conditions divided inta regions and months with indication of year.H Maximum depth of snow at each station and <luring each of the 72 years  with indication of month.I  Various stalistical information derived from the values of table H.K Highest and lowest yearly maximum and difference in cm.L Extreme values of the depth of snow.

    Fulltekst (pdf)
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  • 78.
    Persson, Christer
    SMHI, Forskningsavdelningen, Luftmiljö.
    Local scale plume model for nitrogen oxides. Verification1986Rapport (Annet vitenskapelig)
    Abstract [en]

    A plume dispersion modet on local scale (0 - ~20 km) including atmospheric chemistry for nitrogen oxides was developed and presented in RMK 41 (1984). The model is designed for and used in practical environmental planning for e.g. coalfired power plants. In this study a verification of the model by means of plume data from several European power plants has been performed. The verification shows that the model is capable of describing the NO2- formation in power plant plumes in most weather situations in a fairly accurate way. No important systematic errors seem to be present and the correlation coefficient for NO2-fractions of total NOx is found to be about O.7 out to at least 1000 seconds after emission.The calculations are based only on routine meteorological data, emission data and ozone concentrations in the ambient air. Thus, the calculations have been performed in the same way as in the case of practical environmental planning, which gives a realistic picture of the potential of the modet for practical applications. From the results it is obvious that the meteorological conditions and the ambient ozone concentration are of great importance for the relative amount of NO2 in the plume. On a local geographical scale the plume chemistry is controlled by the entrainment of ambient air.

    Fulltekst (pdf)
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  • 79.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Funquist, Lennart
    SMHI, Forskningsavdelningen, Oceanografi.
    Local scale plume model for nitrogen oxides: Model description1984Rapport (Annet vitenskapelig)
  • 80.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Regional spridningsmodell för Göteborgs och Bohus, Hallands och Älvsborgs län: Regional luftmiljöanalys för år 19911994Rapport (Annet vitenskapelig)
    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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  • 81.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Omstedt, Gunnar
    SMHI, Forskningsavdelningen, Luftmiljö.
    En modell för beräkning av luftföroreningars spridning och deposition på mesoskala1980Rapport (Annet vitenskapelig)
    Abstract [sv]

    Mängden föroreningar, som förs till atmosfären, har under de senaste trettio åren kraftigt ökats. Deposition av dessa till marken leder till en rad biologiska effekter. Risker för skador på olika ekosystem genom deposition av tex tungmetaller och syra har därför alltmer börjat diskuteras som viktiga lokaliseringskriterier för fossileldade kraftverk och vissa större industrier. Depositionen av bly i omedelbar närhet av livligt trafikerade motorleder är ett annat exempel där negativa miljöeffekter befaras.

    Uppställandet av effektrelaterade utsläppskriterier medför ett behov av redskap för att kunna göra kvantitativa uppskattningar av förväntade depositioner i omgivningen av en källa. För kraftverk kan behovet av information om depositionsfördelningen, som underlag för lokaliseringsbeslut, röra ett område med flera hundra kilometers utsträckning.

    Vid studier av den lokala spridningen runt en punktkälla har under lång tid den gaussiska plymmodellen varit allmänt använd. Den utgör ett enkelt och i många fall mycket bra hjälpmedel, men har avsevärda begränsningar i de fall då depositionsprocesser och kemiska omvandlingar måste inkluderas i beräkningarna. I modeller baserade på diffusionsekvationen, där vissa antaganden om den turbulenta diffusiviteten görs (sk K-teori), finns möjlighet att på ett väsentligt mer realistiskt sätt inkludera processer som rör deposition och kemiska omvandlingar. Nackdelen är dock att den matematiska behandlingen blir mer komplicerad.

    Numeriska lösningar av diffusionsekvationen har använts av tex Bo in & Persson (1975) och Omstedt & Rodhe (1977). I båda fallen gällde tillämpningarna föroreningsspridning på storregional skala. Maul (1977) har presenterat en analytisk lösning, som tillämpats på föroreningsspridning på mesoskala. Svårigheterna vid tillämpningen av K-teorin är framförallt att bestämma riktiga värden på de ingångsparametrar som fordras. För analytiska lösningar finns dessutom matematiska hinder för godtyckliga vind- och diffusivitetsprofiler. Detta har resulterat i att beräkningar med K-modeller hittills huvudsakligen utförts för några enkla medelprofiler.

    Avsikten med föreliggande projekt har varit att utveckla en för praktiskt brukanvändbar spridningsmodell för studier av torr- och våtdepositionen av föroreningar på lokal- och mesoskala, där godtyckliga vind- och diffusivitetsprofiler kan användas. Dessa genereras med hjälp av en gränsskiktsmodell för olika vädersituationer.

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  • 82.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Grennfelt, P.
    IVL.
    Kindbom, K.
    IVL.
    Lövblad, Gun
    IVL Swedish Environmental Research Institute.
    Svanberg, P-A
    IVL.
    Luftföroreningsepisoden över södra Sverige 2–4 februari 19871987Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
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  • 83.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Rodhe, H.
    MISU.
    De Geer, L-E
    FOA.
    The Chernobyl accident – A meteorological analysis of how radionucleides reached Sweden1986Rapport (Annet vitenskapelig)
    Abstract [en]

    The atmospheric transport to Sweden and the deposition there of radioactive material following the Chernobyl accident have been described on the basis of radiological and meteorological data and theoretical calculations of despersion. The radioactive cloud created by the explosion at 01. 23 local time on 26 April 1986 was transported north- west and north over the Baltic Sea. An extensive long-distance transport of radionuclides to Scandinavia and Finland took place. Sweden was affected by dry deposition, including fairly large hot particles and also by wet deposition. Wet deposition occurred in connection with precipitation over eastern Sweden on 28 April, which further affected parts of northern Sweden until 30 April. Deposition of caesium mainly occurred through wet deposition. In the case of certain other radionuclides, including 95Zr and 239 Np, a considerable part of the deposition occurred in the form of dry deposition. The study has attempted to estimate the probabil ity of Sweden being affected to a similar extent following a major nuclear accident outside the country's borders.

    Fulltekst (pdf)
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  • 84.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Model calculations of dispersion of lindane over Europe: Pilot study with comparisons to easurements around the Baltic Sea and the Kattegat1996Rapport (Annet vitenskapelig)
    Abstract [en]

    A pilot project is presented, where the dispersion model MATCH is tested for studies of dispersion and deposition of lindane (y-HCH) over Europe. Comparisons between rough model calculations and long-term measurements at stations around the Baltic Sea indicate a positive correlation both for concentration in air and for wet deposition, but the model results are a factor of 3-10 larger than the measurements. The MATCH model simulations seem to agree better with observations from the Swedish West-coast and North Sea areas. Since the model calculations in this pilot project are performed in a very simplified way we cannot exclude that uncertainties in our calculations can cause the detected differences. However, we think that also emission data, especially for Sweden and Finland, and the respresentativity of measurements should be investigated further in a future study.

    Fulltekst (pdf)
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  • 85.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Regional luftmiljöanalys för Västmanlands län baserad på MATCH modell-beräkningar och mätdata: Analys av 1994 års data1997Rapport (Annet vitenskapelig)
  • 86.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    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 methods1996Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
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  • 87.
    Persson, Gunn
    et al.
    SMHI, Affärsverksamhet.
    Bärring, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Rummukainen, Markku
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Climate indices for vulnerability assessments2007Rapport (Annet vitenskapelig)
    Abstract [sv]

    Behovet av information om klimatets förändring och dess effekter på olika regioner och sektorer ökar stadigt. För att belysa frågeställningar runt klimatets utveckling, dess påverkan och behov av anpassning behövs projektioner av framtidens klimat. Den generella kunskapen om klimat baseras oftast på erfarenhet av tidigare klimat, väderobservationer, prognoser och återanalyser av historiska data. För att hantera framtidens föränderliga klimat behöver vi utveckla metoder för att förfina användningen av information från klimatmodeller. Klimatindex, formulerade med avnämarperspektiv i fokus och beräknade utifrån data från klimatmodeller, är ett sätt att kommunicera den komplexa frågan om effekter av klimatets framtida utveckling. Klimatindex kan vara välkänd information som summerad nederbörd eller medeltemperaturer men kan också beskriva mer komplexa relationer och då innefatta till exempel tröskelvärden eller exponeringstid för olika förhållanden. I denna rapport beskrivs ett omfattande material av klimatindex baserade på beräkningar med två regionala klimatmodeller utifrån olika utsläppsscenarier och globala klimatmodeller. Materialet har legat till grund för arbetet inom den svenska Klimat- och sårbarhetsutredningen (M2005:03), men har även framtagits i samarbete med andra avnämargrupper. De flesta klimatmodeller och klimatscenarier som ligger till grund för indexberäkningarna har tidigare dokumenterats i andra rapporter men ges här en övergripande beskrivning. Till rapporten bifogas en DVD med det omfattande kartmaterial som illustrerar indexberäkningarna och tillhörande information. Materialet finns även tillgängligt på www.smhi.se.

    Fulltekst (pdf)
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  • 88.
    Persson, Thomas
    SMHI.
    Solar irradiance modelling using satellite retrieved cloudiness: A pilot study1997Rapport (Annet vitenskapelig)
    Abstract [en]

    Accurate measurements of incoming solar radiation at the Earth' s surface are made by present ground based networks. The data are of high quality and high  sampling frequency but there is a lack of spatial coverage. Areas of great interest may not have any observations at all. Since clouds are the major modulators of solar radiation, the possibility to use satellite retrieved  cloudiness as a basis for irradiance calculations has been investigated.

    Data from the cloud classification model SCANDIA, which utilises NOAA AVHRR data as input, have been analysed and the influence of SCANDIA classed clouds on incoming solar radiation at the ground has been approximately quantified. Hourly mean values of global irradiance, measured at the twelve stations in the solar radiation network of SMHI, were taken as reference data.

    Derived cloud transmittances are relatively close to those found by others using manually observed and classified clouds. In this study satellite data from only one month (April 1995) have been analysed. To determine mean cloud transmittances of high accuracy far more data (from >1 year) have to be used.

    In spite of the division into subgroups of cloud classes made by SCANDIA, it is shown that individual cloud transmittances for one and the same cloud class scatter a lot. Therefore it is difficult to accurately calculate solar irradiances, representative for short time intervals (>1 hour), with only cloud transmittances (and solar elevation) as input data. Though, for modelling accumulated solar irradiance during longer time intervals (days or months), satellite derived cloudiness is thought to be very valuable information.

    It is also shown that for accurate calculations of global irradiance under clear skies, additional information about atmospheric turbidity and water vapour content is urgently needed.

    Fulltekst (pdf)
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  • 89.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Extended back-trajectories by means of adjoint equations2004Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
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  • 90.
    Robertson, Lennart
    SMHI, Forskningsavdelningen, Luftmiljö.
    Modelling of anthropogenic sulfur deposition to the African and South American continents1996Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
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  • 91.
    Robertson, Lennart
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Engardt, Magnuz
    SMHI, Forskningsavdelningen, Luftmiljö.
    MATCH - Meso-scale Atmospheric Transport and Chemistry modelling system: Basic transport mode/ description and control experiments with 222Rn1996Rapport (Annet vitenskapelig)
    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.

    Fulltekst (pdf)
    fulltext
  • 92.
    Rummukainen, Markku
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Methods for statistical downscaling of GCM simulations1997Rapport (Annet vitenskapelig)
    Abstract [en]

    General Circulation Models (GCMs) are used to study the change of climate due to increases in greenhouse gases in the atmosphere. As GCMs operate on !arge spatial scales, and, furthermore, as the GCM-simulated temporal resolution corresponds to monthly averages at best, the usefulness of GCM data in impact studies and other applications is limited. The present-day free troposphere is modeled relatively well by the coarse GCMs, whereas local or even regional characteristics in surface or near-surface climate variables, their variability and the likelihood of extreme events cannot be obtained directly from GCMs. The same is likely true in the case of climate change experiments with GCMs. The results from GCMs can be superimposed on climatological local­ scale time series or interpreted in some other way in order to address the needs of impact studies. This is known as "downscaling" of GCM simulations. In this survey, five different downscaling methods are introduced. These are the conventional, the statistical, the stochastic, the dynamical and the composite methods. Only the statistical and, to a lesser extent, the stochastic approaches are discussed in detail. This survey is a planning document in the SWECLIM program.

    Fulltekst (pdf)
    fulltext
  • 93.
    Rummukainen, Markku
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    On the Climate Change debate1999Rapport (Annet vitenskapelig)
    Abstract [en]

    The debate on the 'science of climate change' focuses mainly on 1) whether the climate is changing and 2) if mankind's activities play a role in climate change. This report was written after the symposium on "Man-made versus natural climate change; Changes in climate during the past 100 years from a Holocene perspective" at the Royal Swedish Academy of Sciences, March 1999, where these issues were also dealt with. The report provides same additional background, review of same recent work on climate and includes some more philosophical reflections as well. The following topics are addressed, in same detail:

    • introduction to the climate change debatewhat is known of climate (change)
    • what is known of climate ( change) in the near past and in geological time scales
    • how climate variability and climate change are interrelated
    • what factors force climate ( change and/or variability)
    • same observations relevant to the climate change debate
    • same recent climate modeling relevant to the climate change debate
    Fulltekst (pdf)
    fulltext
  • 94.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Källén, Erland
    Meterologi.
    Moen, Lars
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Rodhe, J.
    SMHI.
    Tjernström, M
    SWECLIM - The First Three Years2000Rapport (Annet vitenskapelig)
    Abstract [en]

    The Swedish Regional Clirnate Modeling Program (SWECLIM) is a 6-year national research effort with the airn of providing the Swedish society with more detailed regional climate scenarios than typically available from international global clirnate rnodel simulations. The background is the perceived further enhancernent of the greenhouse effect that is projected to lead to global warming and other changes m the clirnate systern. SWECLIM provides users within governmental organizations, businesses, political decision-rnaking, as well as media and the general public with expertise and synthesis of clirnate change issues, science, results and the detailed regional climate scenarios, to further the understanding of the future changes, to facilitate planning and realization of rnitigation and/or adaptation measures. This requires developrnent and use of regionalization techniques, regional rnodeling tools and other studies of the relevant regional processes and collected data. Apart from hydrological interpretation done of the clirnate scenarios, SWECLIM does not perfonn irnpact studies. Additional concretization of the clirnate scenarios by externa! groups, who possess branch-specific irnpact assessrnent expertise, is supported and encouraged by SWECLIM.

    This report describes the background of the SWECLIM-prograrn, the work undertaken during program phase 1,l asting from 1997 to June 2000. The model developrnent, the prepared regional climate and water resources scenarios, results from statistical downscaling and basic process studies and data analyses, as well as the interaction with users and media are covered. Finally, a brief introduction to the program phase 2 plans are provided.

    Fulltekst (pdf)
    fulltext
  • 95.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Persson, Gunn
    SMHI, Affärsverksamhet.
    Ressner, Elisabet
    SMHI.
    Anpassning till klimatförändringar: Kartläggning av arbete med sårbarhetsanalyser, anpassningsbehov och anpassningsåtgärder i Sverige till framtida klimatförändring2005Rapport (Annet vitenskapelig)
    Abstract [sv]

    Denna rapport är resultatet av ett uppdrag från Naturvårdsverket till SMHI (NV dnr 235-5045-04H k), som genomförts under hösten 2004. Syftet är att få en överblick över vilka aktörer som för närvarande är aktiva med att analysera eventuella effekter på samhället och att kartlägga anpassningsbehov. Avsikten är också att få en bild av planerade eller redan genomförda insatser och skyddsåtgärder på grund av en befarad klimatförändring. Kartläggningen omfattar ett flertal svenska myndigheter, företag samt ett antal relevanta bransch- och intresseorganisationer och forskningsfinansiärer.I rapporten redovisas även översiktligt de hinder i anpassningsarbetet som identifierats samt önskemål om förbättrat beslutsunderlag.Slutligen förs en översiktlig diskussion om tänkbara sektoriella effekter avav klimatförändringen, baserad på tidigare avnämarkontakter och forskningsinsatser inom området

    Fulltekst (pdf)
    FULLTEXT01
  • 96.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Räisänen, Jouni
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bringfelt, Björn
    SMHI.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Graham, Phil
    SMHI, Affärsverksamhet.
    RCA - Rossby Centre regional Atmospheric climate model: model description and results from the first multi-year simulation1997Rapport (Annet vitenskapelig)
    Abstract [en]

    The first version of the Rossby Centre regional climate model (RCA) has now been developed. The RCA model is based on a parallel coding of the operational weather forecast model HIRLAM. Some modifications have been done on the model formulation, especially in its surface/snow/soil scheme, in an attempt to include the regional and local scale climate-modifying forcing up to time scales of several years. The physical parameterization choices in HIRLAM and in RCA are discussed in some detail. One of the notable features in RCA is that the regional sea ice climate, as well as ice on the numerous lakes in the region, has been included in a crude, but time-efficient fashion. It appears that realistic modeling of the sea/lake ice is most important for modeling the regional climate in the Nordic region.

    The RCA model has been run fora ten-year period, focusing on the Nordic region, using results from a coupled ocean-atmosphere general circulation model. In this first multi-year simulation, the regional resolution was 44 km.  Several results are illustrated from this regional simulation and they are compared to the driving global model data, to analyzed observations and to Swedish station data for the 1961-90 period. The apparent model development needs are also discussed briefly.

    Fulltekst (pdf)
    fulltext
  • 97.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    SWECLIM participants, SWECLIM participants
    The Swedish regional climate modeling program 1996-2003: Final report2003Rapport (Annet vitenskapelig)
    Abstract [en]

    The Swedish Regional Climate Modeling Program (SWECLIM) was a 6.5-year national research effort with the aim of providing the Swedish society with more detailed regional climate scenarios than those available from international global climate mode! simulations. SWECLIM built up a new scientific niche in Sweden, namely that of climate modeling, provided users with regionally detailed climate scenarios, expert advice and synthesis of climate changescience. Regional climate modeling was a major activity, supported with studies of climate processes as well as on observed data on the Baltic Sea, regional hydrology and meteorology. The major impact study part was on hydrological modeling, to elaborate the potential impact of regional-scale climate change on hydropower, dam safety and water resources in general. Other types of impact studies were not performed by SWECLIM itself, but means were provided for outside experts to pursue such knowledge. This fmihered the general understanding of climate change and created new insights into planning processes, especially in Sweden, but also on theNordic, European and global arenas.Examples of practical users of the results were experts and decision-makers within national, regional and local administration, organizations, businesses, politicians, as well as media and the general public. These Swedish cfforts on climate science also contributed to international research and assessment networks, and to the quest for better knowledge base to act on in dealing with the climate problem.This repor! provides the final reporting of the SWECLIM-program, building on earlier reports and complements the results published in scientific journals, as reports, presented in meetings and provided to the general public. The focus here is on the work undertaken <luring program phase 2, lasting from July 2000 to June 2003.

    Fulltekst (pdf)
    fulltext
  • 98.
    Räisänen, Jouni
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    CO2-induced climate change in northern Europé: comparison of 12 CMIP2 experiments.2000Rapport (Annet vitenskapelig)
    Abstract [en]

    The results of 12 coupled atmosphere-ocean general circulation model experiments participating in the second phase of the Coupled Model Intercomparison Project (CMIP2) are studied with focus on the area of northern Europe. The variables considered are surface air temperature, precipitation and sea level pressure. The 80-year control simulations are first compared with observational estimates of the present climate. Several aspects of the simulated CO2-induced climate changes, defined by subtracting the control run  seasonal or annual means from 20-year perturbation run means around the transient doubling of CO2, are then studied. The common features and individual variations in the simulated climate change are documented. Particular attention is put on expressing the interexperiment agreement in quantitative terms and on estimating the relative contribution of model- simulated internal variability to the interexperiment variance. For that purpose, a new statistical framework is developed. Finally, an attempt is made to statistically relate the interexperiment differences in the simulated climate change in northern Europe to aspects of the control climates, global climate change and some of the basic model characteristics.

    A summary of the main findings is given in the last section of the report.

    Fulltekst (pdf)
    fulltext
  • 99.
    Räisänen, Jouni
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Simulation of present-day climate in Northen Europé in the HadCM2 OAGCM1998Rapport (Annet vitenskapelig)
    Abstract [en]

    The performance of a global coupled atmosphere-ocean general circulation model, HadCM2, in simulating present-day climate in Sweden and Northern Europe is studied. The study is motivated by the use of HadCM2 within the SWEdish regional CLimate Modelling programme SWECLIM. In particular, HadCM2 provides the boundary data for the first regional high-resolution climate simulations conducted at the Rossby Centre.

    HadCM2 is probably one of the best present global climate models, and several aspects of the simulated control climate are in reasonable agreement with observations. However, some quantitative shortcomings are also evident. In Northern Europe, the simulated summer temperatures are a few degrees colder than those observed, and their interannual variability appears too large. In winter, a local warm bias occurs around the Baltic Sea, which is too warm to get an ice cover in the model. The effect of the Scandinavian Mountains on the distribution of precipitation is distorted by the model's modest (2.5° lat x 3.75° lon) resolution. The simulated total cloudiness generally exceeds that observed.

    In comparing the model results with the records of individual climate stations, the first problem is to derive the model-simulated value at the station location from the original discrete grid box values. Several choices of doing this are examined and, at least in comparison with observed temperature and precipitation at Swedish stations, the conclusions frequently depend on how the model-simulated station value is defined.

    It is also studied how the climate in the 10-year HadCM2 control run used for dynamical downscaling at the Rossby Centre differs from a longer (240-year) control run made with the same model. In most cases, the differences between the 10-year and 240-year runs are smaller than those between the former and observations. Nevertheless, some of these differences are large enough to be kept in mind when comparing the 10-year control run with, for example, a similar run with increased CO2.

    Fulltekst (pdf)
    fulltext
  • 100.
    Räisänen, Jouni
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    GCM driven simulations of recent and future climate with the Rossby Centre coupled atmosphere - Baltic Sea regional climate model RCAO2003Rapport (Annet vitenskapelig)
    Abstract [en]

    A series of six general circulation model (GCM) driven regional climate simulations made at the Rossby Centre, SMHI, during the year 2002 are documented. For both the two driving GCMs HadAM3H andECHAM4/OPYC3, a 30-year (1961-1990) control run and two 30-year (2071-2100) scenario runs have been made. The scenario runs are based on the IPCC SRES A2 and B2 forcing scenarios. These simulations were made at 49 km atmospheric resolution and they are part of the European PRUDENCE project.Many aspects of the simulated control climates compare favourably with observations, but some problems are also evident. For example, the simulated cloudiness and precipitation appear generally too abundant in northern Europe (although biases in precipitation measurements complicate the interpretation), whereas too clear and dry conditions prevail in southern Europe. There is a lot of similarity between the HadAM3Hdriven (RCAO-H) and ECHAM4/OPYC3-driven (RCAO-E) control simulations, although the problems associated with the hydrological cycle and cloudiness are somewhat larger in the latter.The simulated climate changes (2071-2100 minus 1961-1990) depend on both the forcing scenario (the changes are generally larger for A2 than B2) and the driving global model (the largest changes tend to occur in RCAO-E). In all the scenario simulations, the warming in northern Europe is largest in winter or autumn. In central and southern Europe, the warming peaks in summer and reaches in the RCAO-E A2 simulation locally 10°C. The four simulations agree on a general increase in precipitation in northern Europe especiallyin winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ a lot between RCAO-H and RCAO-E. Thisreflects very different changes in the atmospheric circulation during the winter half-year, which also have a large impact on the simulated changes in windiness. A very large increase in the lowest minimumtemperatures occurs in a large part of Europe, most probably due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases.

    Fulltekst (pdf)
    FULLTEXT01
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