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  • 1.
    Alexandersson, Hans
    et al.
    SMHI.
    Dahlström, Bengt
    SMHI, Core Services.
    Future climate in the Nordic region – survey and synthesis for the next century1992Report (Other academic)
  • 2.
    Alexandersson, Hans
    et al.
    SMHI.
    Eriksson, Bertil
    SMHI.
    Climate fluctuations in Sweden 1860–19871989Report (Other academic)
  • 3.
    Alexandersson, Hans
    et al.
    SMHI.
    Gollvik, Stefan
    Meterologi.
    Meuller, Lars
    SMHI.
    An energy balance model for prediction of surface temperatures1991Report (Other academic)
  • 4.
    Andersson, Camilla
    et al.
    SMHI, Research Department, Air quality.
    Bergström, Robert
    SMHI, Research Department, Air quality.
    Bennet, Cecilia
    SMHI, Research Department, Air quality.
    Thomas, Manu
    SMHI, Research Department, Air quality.
    Robertson, Lennart
    SMHI, Research Department, Air quality.
    Kokkola, Harri
    FMI.
    Lehtinen, Kari
    FMI.
    MATCH-SALSA: Multi-scale Atmospheric Transport and CHemistry model coupled to the SALSA aerosol microphysics model2013Report (Other academic)
    Abstract [en]

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

  • 5.
    Andersson, Tage
    SMHI, Research Department.
    Boundary clear air echos in southern Sweden2000Report (Other academic)
    Abstract [en]

    The C band weather radars of today are sensitive enough to record clear air echos from the boundary layer during the warmer seasons even in latitudes as high as Scandinavia. Such clear air echos have long been recognised in the US and a.o. used to retrieve the wind. Curiously enough, in Europe there has been, and perhaps still is, a wide spread belief among meteorologists that boundary layer clear air echos are absent there. The probable reason is that since European weather radars are almost only used to monitor precipitation, in most countries weak echos, supposed not to represent precipitation, are suppressed. This may be performed in many ways, for instance by using the STC (Sensitivity Time Control, also called Swept Gain) which suppresses echos close to the radar, or by thresholding weak echos in the radar images used. The threshold is usually about 10 dBz, and since most clear air echos are weaker, they do not appear in the images, though the radar rnight have recorded them.

    That these clear air echos actually are echos from the air, as from sharp refractive index gradients, insects or birds, is evident since Doppler radars show that they move, generally approximately with the winds recorded by other means. The exceptions are from targets heading towards a specific goal, as rnigrating birds, birds leaving a nocturnal roost and locust swarms.

    The concept 'clear air echos' refers to echos from a non-precipitating atmosphere. There is no commonly agreed stringent definition of clear air echos.

  • 6.
    Andersson, Tage
    SMHI, Research Department.
    Using the Sun to check some weather radar parameters2000Report (Other academic)
    Abstract [en]

    Precipitation rnonitoring is a rnain task for weather radar applications. In quantitative applications, as estirnation of the rain rate, the fundamental quantity is the rneasurernent of the intensity of the retum signal strength, giving the so called reflectivity factor, or reflectivity, which is the rnain parameter for those estirnates. The calibration of weather radars for this purpose has been a rnain task in radar rneteorology since the first atternpts of estirnating rain rates in the early 1950ies. In spite of this there is still no intemational accepted procedure for this calibration and each rnanufacturer has his own calibration scherne.

    There is evidently a need fora target to calibrate against, which is cornrnon for all radars and easily accessible. This points towards astronornical targets. The rnoon is such a possible target, though the echo from it is too weak for routine calibrations. The sun ernits radiation in the radar frequencies. These signals are already widely used to deterrnine the orientation of the antenna (azirnuth and elevation angle ). The intensity of the radiation in these frequencies is not constant, but is rneasured by sorne observatories and rnay be used as a calibration source.

    The present work is an atternpt to design a calibration or checking procedure that can be used when the radar is working operatively.

  • 7.
    Andersson, Tage
    et al.
    SMHI, Research Department.
    Mattisson, Ingemar
    SMHI.
    A field test of thermometer screens1991Report (Other academic)
    Abstract [en]

    For a period of nearly one year temperature readings from small sensors (high quality platinum resistance thermometers) in conventional screens (Stevensson type) and emaller screens (Lambrecht, Young and Vaisala) have been compared to those from a sensor of the same type in a ventilated screen (Teledyne). The test was financially supported by the Swedish Civil Board of Aviation and CDS Mätteknik, Skara. The reading from the Teledyne screen was used as reference and considered the 'true' air temperature. The deviations from the reference were mainly due to two factors:- the thermal inertia of the screens- radiation errors.The thermal inertia is largest for the larger screens. With rapid air temperature changes and calm winds the larger (Stevenson) screens lag behind much more than the smaller ones. Also the radiation errors are largest for calm winds. The extreme errors then occur during calm winds and clear sky. The errors found are larger than given in the literature. The largest error noted, +3. 6°C for one of the Stevenson screens, occurred a calm, clear evening. Generally the extreme errors occurred at sunset and sunrise, not in the a~ternoon when the irradiation has its maximum, because it then usually is windy. Generally the smaller screens followed the reference better than the Stevenson ones. However, with calm winds, clear sky and snow cover the small screens may rapidly get overheated. The averages for longer periods (months)

  • 8.
    Bengtsson,, Lennart
    et al.
    SMHI.
    Gustafsson, Nils
    SMHI, Research Department, Meteorology.
    Döös, Bo
    SMHI.
    Söderman, Daniel
    Helsinki University in Finland.
    Moen, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Thompson, Thomas
    SMHI.
    Jakobsson, Paul
    SMHI.
    Bleckert, Gunnar
    SMHI.
    Henriksson, Ann-Beate
    SMHI.
    Lindgren, Bo
    SMHI.
    Kållberg, Per
    SMHI, Research Department, Meteorology.
    The Meteorological Auto Code (MAC) and Numerical Weather Prediction (NWP) at SMHI2016Report (Other academic)
    Abstract [en]

    Sweden was a pioneering country in the development of NumericalWeather Prediction (NWP). The worlds first operational numerical forecast was produced already in 1954 by the International Meteorological Institute in Stockholm. SMHI started a bit later, but in 1961 a long term program for development of NWP was initiated. The activities grew gradually during the 1960’s and resulted in a core component for the SMHI forecast services. An early challenge was to overcome the limited computational resources with slow computational speed, small memory size and primitive software support. It was necessary to compensate for these limitations with dedicated work and creativity. A core component in this work was the software system MAC (Meteorological Auto Code) that was developed by the NWP group at SMHI. The MAC system is described in detail in this report and it included all computational software needed for the weather service, for example numerical models, objective analysis techniques, automatic data extraction, quality control of observations as well as forecast products in graphical or digital form.

    We hope that this report will provide the younger generation with some insight into the conditions for development of NWP during the 1960’s.

  • 9.
    Bodin, Svante
    SMHI, Research Department.
    Development on an unsteady atmospheric boundary layer model1974Report (Other academic)
    Abstract [en]

    To serve as an aid in preparing lecal ferecasts as well as landing ferecasts at airports, a develepment ef an atmospheric boundary layer model has been started at SMHI. The model is going to use large scale wind, temperature and moisture predictions from a numerical weather prediction model as variable boundary conditions. Instead ef using the ordinary Ekman boundary layer equations an approach due te L N Gutman (1969) has been used in deriving a set of one-dimensional boundary layer equations. It is shown that this formulation filters out inertial- diffusive oscillations, which are present in an Ekman boundary layer due to time variation in the geostrephic wind.

    Experiments with variable large scale winds have been done, using a simple dry medel with prescribed variations in the boundary values for wind and temperature. A turbulent exchange coefficient formulation has been used, which is based on Monin & Obukhov´s similarity theory and which uses a mixing length formulation due to Blackadar. For the numerical solution a Crank-Nicolson scheme has been used. The computations show large differences between the steady state and the unsteady state solutions.This is shown in wind hodegraphs as well as in time functions of friction velocity,u* and cross isobar angle. Finally, from two different analytical solutions as well as a finite difference solution of the heat conduction equation, heat fluxes at the earth's surface due to heat conduction in the soil have been computed. These analytical solutions have been compared in terms of accuracy and efficiency.

  • 10.
    Bodin, Svante
    SMHI, Research Department.
    En numerisk prognosmodell för det atmosfäriska gränsskiktet, grundad på den turbulenta energiekvationen1979Report (Other academic)
    Abstract [en]

    The inter est in numerical modeling of the atmosphericboundary layer has grown considerably over the lastdecade. At SMHI and el s ewhere boundary layer modelsfind app l i c a ti on s in local forecasting , especially atairports, i n a i r pollution diffusion and disper s ions t udi e s and i n wind energy programmes .In this report an one - dimensio nal nume r ical boundarylayer model is der iv e d a nd numeri cal simulatio ns ofboundary layer data f r om Australia and Finla nd arepresented and d is cussed. The model, which is the f i rststep towards a three-dimens ional model, is based onthe so-called Gutman a pproach and incorporates theturbulent energy e quation f or turb ulence closure . Ascale analysis is performed , that shows that unless agrid distance of 20 km or less can be use d i n a threedimensionalmodel it is more profitable t o use an onedimensionalone with more sophisticated physical parameterizations.The model also includ e s condensat i on, i e fog andclouds, and complete radiat i on computations. A predictiveequation for surface temperature is used inconjunction with a simple soil moisture model.The numerical solution employs a variety of the CrankNicolsonscheme called Laasonen's scheme. The verticalcoordinate is transformed log-linearly into a new heightcoordinate to allow better resolution close to theground. 35 grid points are used to describe the boundarylayer up to 2000 m. A time step of 4 minutes has beenused in the simulations.Two versions of the model, the Gutman version andausual "Ekman" version, have been tested on day 33 and34 of the Wangara data. The two versions have been comparedand the Ekman version has also been compared withthe simulations of Yamada & Mellor (1975).The results show that the Ekman version is superiorwhen simulating the wind of the Wangara data. The thermalboundary layer development is very well predictedby both versions. Comparisons with Yamada & Mellorspeak in favour of the present model.Conclusions are drawn and some future work is outlined .The model is intended to undergo operational tests atArlanda airport in the near future.

  • 11.
    Bodin, Svante
    et al.
    SMHI, Research Department.
    Fredriksson, Ulf
    SMHI, Core Services.
    Uncertainty in wind forecasting for wind power networks1980Report (Other academic)
  • 12.
    Bringfelt, Bertil
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Räisänen, Jouni
    SMHI, Research Department, Climate research - Rossby Centre.
    Gollvik, Stefan
    Meterologi.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Professional Services.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    The land surface treatment for the Rossby Centre Regional Atmospheric Climate Model - version 2 (RCA2)2001Report (Other academic)
    Abstract [en]

    A new version of the land surface scheme has been completed and is now applied in comparative tests of version 2 of the Rossby Centre Regional Atmospheric Climate Model (RCA2) using analysed fields from the ECMWF reanalysis project (ERA). The scheme contains two soil layers and a vegetation layer. There are two prognostic temperatures, one covering the top soil layer plus vegetation and one for a second, deeper soil layer. There is also a third, bottom soil temperature relaxed to six-hourly ERA fields. For soil moisture there are two prognostic layers but no bottom relaxation is used. A hydrologically-based soil moisture model (beta model) is used to represent subgrid soil moisture variability. A hydrological snow model makes regard to subgrid temperature variability using a geographical database for variance of topography. There are equations for heat and moisture exchange between the two soil layers. Here the hydraulic and thermal properties depend on soil type and soil moisture. Transpiration flux transports moisture from both soil layers depending on a stomatal resistance of vegetation surfaces as function of daylight intensity, soil water deficit, fraction of frozen soil water, air temperature and water vapour pressure deficit in the air. A treatment of rainfall interception on vegetation is used, broadly following the ISBA model, with a vegetation layer storing intercepted water. Subgrid weighting of albedo, surface roughness and parameters for calculating surface resistance is made using a geographical database for area fraction of forest and open land. The leaf area index varies seasonally for short vegetation and for deciduous forest, but not for coniferous forest. A soil freezing/melting algorithm influencing soil temperature is used. Implicit methods are used for solving the equations of most surface variables. A summary of model results compared to observations, is given at the end of the report.

  • 13.
    Bringfelt, Björn
    SMHI.
    A comparison of forest evapotranspiration determined by some independent methods1980Report (Other academic)
  • 14.
    Bringfelt, Björn
    SMHI.
    A forest evapotranspiration model using synoptic data1982Report (Other academic)
  • 15.
    Bringfelt, Björn
    SMHI.
    Test of a forest evapotranspiration model1986Report (Other academic)
  • 16.
    Bringfelt, Björn
    et al.
    SMHI.
    Backström, Hans
    SMHI, Professional Services.
    Kindell, Sven
    SMHI, Professional Services.
    Omstedt, Gunnar
    SMHI, Research Department, Air quality.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Ullerstig, Anders
    SMHI, Research Department, Climate research - Rossby Centre.
    Calculations of PM-10 concentrations in Swedish cities - Modelling of inhalable particles1997Report (Other academic)
  • 17.
    Collins, William.G.
    SMHI.
    A parameterization model for calculation of vertical fluxes of momentum due to terrain induced gravity waves1976Report (Other academic)
    Abstract [en]

    Various sources of informatio n indicate vertic al fluxes of mountain induced wave momentum to be on the order of several tenths of a Pascal over mountaineous terrain . The implied wind tendencies in layers of wave absorption in typical situations are several meters per second per day . On the basis of the size of this probable effect , a parameterization model has been developed to calculate t h e momentum fluxes within the framework of a large- scale numerical weather prediction model. The calculation model assumes a continuous linear wind profile as well as constant stability within each layer . The hydrostatic assumption is made for the total motion . The vertical velocities and resultant vertical momenturn fluxes are caused by the air being forced over the topography . For this mode l , the individual spectral elements of the terrain height are not important . Rather , an integral ov er the elements is used as the forcing function which determines the momen - turn flux magnitude . This forcing function must be determine-d as a function of horizontal direction for each largescale grid box . Sample calculations are given which illustrate the results possible from the parameterization model .

  • 18.
    Dahlström, Bengt
    SMHI, Core Services.
    Determination of areal precipitation for the Baltic Sea1986Report (Other academic)
  • 19.
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Sulphur simulations for East Asia using the MATCH model with meteorological data from ECMWF2000Report (Other academic)
  • 20.
    Ericsson, Kjell
    SMHI.
    Atmospheric boundary layer field experiment in Sweden 1980, GOTEX II, part I1982Report (Other academic)
  • 21.
    Ericsson, Kjell
    et al.
    SMHI.
    Hårsmar, Per-Olof
    SMHI, Core Services.
    Boundary layer measurements at Klockrike. Oct. 19771980Report (Other academic)
  • 22.
    Eriksson, Bertil
    SMHI.
    Data rörande Sveriges temperaturklimat1982Report (Other academic)
  • 23.
    Eriksson, Bertil
    SMHI.
    Den dagliga och årliga variationen av temperatur, fuktighet och vindhastighet vid några orter i Sverige1977Report (Other academic)
    Abstract [en]

    Hourly observations from aerodroms have been used to calcul atehourly means of the most important climatological variables.For those varibles showing a marked daily and annual variationisopleth diagrams have been analys ed for air temperature, humidi tyand wind velocity. The results are given for 11 places. Theperiod used i s in general the years 1955-1975. In the text shor tcomments are given to the different diagrams. Some differencesand similarities between stations have been pointed out.

  • 24.
    Eriksson, Bertil
    SMHI.
    Den "potentiella" evapotranspirationen i Sverige1981Report (Other academic)
  • 25.
    Eriksson, Bertil
    SMHI.
    Graddagsstatistik för Sverige1980Report (Other academic)
  • 26.
    Eriksson, Bertil
    SMHI.
    Nederbörds- och humiditetsklimat i Sverige under vegetationsperioden1986Report (Other academic)
  • 27.
    Eriksson, Bertil
    SMHI.
    Snödjupsförhållanden i Sverige – Säsongerna 1950/51–1979/801989Report (Other academic)
  • 28.
    Eriksson, Bertil
    SMHI.
    Statistisk analys av nederbördsdata: Del I. Arealnederbörd1979Report (Other academic)
    Abstract [en]

    Precipitation data on mean values for large areas have been analysed from two points of view. In the first section of this report the data have been looked upon as time series. In the second section they have been regarded as samples from a population.

    The reliability of the data is discussed. It is stated that the values are underestimated. The correction factor may be as high as 30%. Half of this correction is related to the representativity of the precipitation network and is mainly due to the fact that the proportion of stations at high levels is too low. The other half is related to measurement errors, mainly losses due to wind, turbulence and evaporation.

    The time series analysis consists of three parts. In the first one a ' so-called run-test is used to investigate the stationarity of the series. There seemst o be no reason to reject the hypothesis that the series are stationary. After that the frequencies of long runs are X2 -tested against a random model and against models with very low autocorrelation lag- one coefficients. The best fit is found for the model without autocorrelation. In the third part some of the series are filtered with low-pass filters. The results are in accordance with the run-test viz that there are no detectable trends neither linear nor cyclic.

    In the second section seven different distribution functions are tested. The following ones are used: Normal, log-normal (both two and three parameters), gamma (two and three parameters), Weibull and FisherTippett type I. The parameters of these functions are estimated with the maximum-likelihood method or the momentum method. The x2 -test gave no definit answer to the question which one is the mast suitable function. It was possible to reject the lagnormal distribution with three parameters, and the threeparameter r-distribution had no advantage compared with the two-parameter version.

    By studying the outermost values of the distributions it was evident that neither the normal nor the lognormal distribution were able to fit the observed data satisfactory. It was not possible to say which of the two distributions, r or Weibull, is the best one. For very low and even very high values the Weibull distribution seems to be able to describe the observedvalues somewhat better than the gamma distribution can do. Arguments can be delivered both in the favour of rand of Weibull.

    The percentiles, according to the gamma distribution, P01, P05, P10, P25, P50, P75, P90, P95 and P99 are presented . Even P01, P05, P95 and P99 calculated from Weibull distribution are given.

    Those monthly values laying outside P01 and P99 as well as those outside P05 and P95 are listed both according to gamma and Weibull distributions.

    A proposal to a climatological terminologi is presented. The range of a climatological variable is divided into 7 classes. These classes contains 1, 4, 20, 50, 20, 4 respectively 1% of the events. The values belonging to the outmost classes are called extreme values, those in the middle class should be called normal values.

    At the end of the report a list is given of the 10 events, which, according to gamma distributions, have the lowest climatological probability. Some cases have extremely low probabilities.

  • 29.
    Eriksson, Bertil
    SMHI.
    Statistisk analys av nederbördsdata: Del II. Frekvensanalys av månadsnederbörd1980Report (Other academic)
    Abstract [en]

    The frequency distributions of monthly precipitation amounts have been investigated. Data from the period 1931-78 for 262 Swedish and 26 Norwegian stations have been used. The statistical analysis consists of determining the capacity of well-known frequency distribution functions to match the empirical distributions. The following functions were tested: gamma distributions with 2 or 3 parameters, log-normaldistributions with 2 or 3 parameters and the Weibull distribution with 3 parameters. The methods used to determine theparameters of the above-mentioned functions were either the momentum or the maximum- likelihood method. About 3500 distributions were studied. The results of the different tests gave a statistically significant answer to the question: Which of the investigated functions is superior to the other functions best in describing the observed distributions? The gamma distribution was found to have the highest score. In 86% of all case s there was no significant difference, at the 90% confidence level, between observed and computed frequencies. The log-normal distribution hasa much lower capacity to describe the empirical distributions studied.

    From the gamma distribution with the obtained values of its shape and scale parameters certain percentile values were computed, namely: P01, P05, P10, P25, P50, P75, P95, and P99. The results are presented in the form of charts. The charts showing monthly isohyets for different percentile values are briefly cornrnented.

    Maps of the variability of monthly precipitation amounts are also presented. The variability is expressed by means to the coefficient of variation. This variability parameter shows small differences between different regions in Sweden.

    The measuring errors of precipitation observations are discussed. Corrections of measured amounts ought to be applied for the three most important errors viz, the aerodynamic, evaporation and adhesion losses. The most important losses and at the same time those which are most difficult to estimate are due to the wind effects around the orifice of the precipitation gauge. The corrections ought to be determined individually for each station and month with regard to the wind regime and the exposure of the gauge for the station concerned. With these factors in mind and knowing the proportions between snow and rain precipitation corrections have been proposed for the monthly values. On an average for all Swedish stations used in this investigation the mean annual amounts of precipitation for the period 1931-78 should be increased by 18%. In the water balance equation the values thus increased seem to agree reasonably well with generally accepted values for evaporation and run-off .

  • 30.
    Eriksson, Bertil
    SMHI.
    Statistisk analys av nederbördsdata: Del III. 200-åriga nederbördsserier1981Report (Other academic)
  • 31.
    Eriksson, Bertil
    SMHI.
    Sveriges Vattenbalans. Årsmedelvärden (1931–60) av nederbörd, avdunstning och avrinning1980Report (Other academic)
    Abstract [en]

    The correction factors, which were proposed in an earlier report RMK 17 (1980) to be applied to measured precipitation amounts, have been used on the normal annual values for the period 1931-60. A map is presented, where corrected values from about 260 stations have been used for the analysis. To get the normal annual evaporation values the normal runoff values have been subtracted from the corrected precipitation annual sums. A map is drawn showing the pattern of the normal evaporation in Sweden. The map and the values show good agreement in those points, where reliable evaporation values are available. The conclusion is drawn that the corrections of the precipitation data have the correct order of magnitude. However, there are of course great uncertainties in the details of the map of the normal evaporation in southern Sweden in some areas values above 500 mm per year appear. In order to verify these results, another independent method must be used. It  seems appropriate to establish regression equations between evaporation and the summer mean temperature and maybe even other variables like wind velocity, cloudiness, vapour pressure deficit.

    Area mean values of runoff, precipitation and evapotranspiration amounts have been calculated from the maps by integration. The mean annual precipitation amount for the whole of Sweden was found to be 745 mm. This value is 28% higher than the value computed from uncorrected data. 18% units are due to corrections for losses due to wind, evaporation and adhesion, when measuring the precipitation amounts. The rest, 10% units, is an effect of the fact that the precipitation stations are too few in higher regions. For the country as a whole is found that somewhat less than 50% of the precipitation evaporates as water vapour into the atrnosphere. In mountanious regions, where the largest precipitation amounts fall, only about 15% dissapear into the air.

  • 32.
    Eriksson, Bertil
    SMHI.
    Temperaturfluktuationer under senaste 100 åren1979Report (Other academic)
    Abstract [en]

    In order to investigate, if it is possible to trace anytendencies to increasing variability of the climate<luring the last decades, series of temperature datahave been treated. Five-day means of temperature havebeen analysed from two aspects. The mean conditions<luring running ten-year-periods have been studied aswell as the fluctuations of the variability (expressedwith the aid of standard deviation). Results in theform of diagrams are presented and cornrnented shortly

  • 33.
    Eriksson, Bertil
    SMHI.
    Vegetationsperioden i Sverige beräknad från temperaturobservationer1978Report (Other academic)
    Abstract [en]

    The starting and ending date of the vegetationen period hasbeen calculated from the Swedish temperature observationnetwork for the period 1961-74. The dates have been determinedfor individual years. The criterium used for the determinationof the dates is daily mean temperature 6° during at least fourday s. Maps showing the mean starting and ending date of thevegetation period as well as the length of period have been drawn.A table is presented giving those years with the earliest andlatest dates of the arrival and end of the vegetation period.

  • 34.
    Gollvik, Stefan
    Meterologi.
    Estimation of orographic precipitation by dynamical interpretation of synoptic model data1984Report (Other academic)
  • 35.
    Haag, Tomas
    SMHI.
    Byggnadsindustrins väderberoende: Seminarieuppsats i företagsekonomi, B-nivå1978Report (Other academic)
    Abstract [sv]

    Redan 1969 visade en undersökning vid Svenska Byggnadsentreprenörsförbundet att byggnadsindustrin var intresserad av en branschanpassad väderprognos. Följande arbete syftar till att sondera byggnadsindustrins väderberoende samt hur en för branschen ändamålsenlig väderprognos bör se ut och distribueras.

    Byggnadsindustrin är som näringsgren mycket betydande för samhällsekonomin. Den svarar för ca 8% av BNP och sysselsätter ca 200 000 årsarbetare. Under senaste 10-årsperioden har det lagts ner mycket arbete föratt nå en rationellare byggnadsproduktion. Detta främst genom utarbetandet av den så kallade systematiska arbetsberedningen. Den syftar till att förebygga störningar och minska konsekvenserna av dessa. Då skall speciellt intresse ägnas åt de mest störningskänsliga punkterna och här måste vädrets inverkan på vissa arbetsoperationer beaktas. Gör man klart för sig vilka arbetsoperationer som är beroende av de olika väderelementen samt ritar in försvarsåtgärder och skyddade reservarbeten i planerna kan man, med hjälp av en ändamålsenlig väderprognos, fatta säkrare beslut om vilka åtgärder som skall utföras.

    Genom att utnyttja denna "byggprognos" kan arbetsledningen två ggr/dag fatta beslut över arbete vid väderberoende arbetsoperationer med hjälp av färska prognoser. Detta medför att försvarsåtgärder används endast då de behövs men då i god tid. Samt att det vid mycket dåliga förhållanden finns reservarbeten planerade som kan påbörjas utan dyrbara uppehåll, dessutom slipper man dyrbara överraskningar vid väderomslag.

    Med ändamålsenlig väderinformation menas en regional prognos med de väderelement som är av vikt för byggnadsindustrin samt att denna byggprognos distribueras på ett lämpligt sätt. Regionernas storlek kommer att variera så att man får så stora regioner som möjligt med "samma" väder. Statens Vägverk har delat in landet i 24 olika regioner vid beställning av sina "vägprognoser". Det är en beprövad indelning som anses vara användbar.

  • 36.
    Holmström, Ingemar
    SMHI.
    Optimization of atmospheric models1976Report (Other academic)
    Abstract [en]

    Applying variational methods toa mathematical model of the atmosphere an entirely new type of equations for forecasting atmospheric parameters is derived. The method also defines vertical eigenfunctions to the model. In a simplified case some of the eigenfunctions are compared with empirically obtained data and conclusions are drawn regarding the validity of some of the approximations in the mathematical model.

  • 37.
    Holmström, Ingemar
    et al.
    SMHI.
    Stokes, John
    SMHI.
    Statistical forecasting of sea level changes in the Baltic1978Report (Other academic)
    Abstract [en]

    By expanding sea level data from 6 Swedish observation stations inte empirical orthogonal functions a very simple picture of the response of the Baltic to atmospheric forcing is obtained. It is found that not less than 65.5 per cent of the total variance is due to a general rise or lowering of the whole surface.The time scale corresponds to the time scale of large scale atmospheric disturbances. This inderdependence has been used in order to establish a regression equation between surface pressure fields and sea level variations which is used for prediction. In the statistical treatment extensive use is made of the empirical orthogonal function technique.

  • 38.
    Häggmark, Lars
    et al.
    SMHI, Core Services.
    Ivarsson, Karl-Ivar
    SMHI, Core Services.
    Olofsson, Per-Olof
    Militära Vädertjänsten.
    MESAN - Mesoskalig analys1997Report (Other academic)
  • 39.
    Häggmark, Lars
    et al.
    SMHI, Core Services.
    Ivarsson, Karl-Ivar
    SMHI, Core Services.
    Olofsson, Per-Olof
    Militära Vädertjänsten.
    MESAN Mesoskalig Analys1997Report (Other academic)
    Abstract [en]

    This report describes the work being done in developing the MESAN system for analyzing surface parameters and clouds. The following parameters are being analyzed:- 2 meter temperature,- precipitation in mm water for 1, 3, 12 and 12 hours accumulation time, and for new snow-cover in cm,- wind speed and direction and gust speed at 10 meter elevation,- visibility,- relative humidity,- total cloud cover,- amount and low clouds,- significant cloud base,- probability of observing significant cloud base,- higt of cloud top,- depth of snow cover, and- sea surface temperature.Hirlam data are normally used as first guess fields. Observatons are taken from synop, metar, Swedish climate stations, satellites, radars and automatic stations. Much work has been devoted to minimizing systematic errors in observations and investigating structure functions of first guess errors.The analys method used is optimal interpolation.

  • 40.
    Jansson, Anna
    et al.
    SMHI, Core Services.
    Persson, Christer
    SMHI, Research Department, Air quality.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    2D meso-scale re-analysis of precipitation, temperature and wind over Europe - ERAMESAN: Time period 1980-20042007Report (Other academic)
    Abstract [en]

    The need for long time series of gridded meteorological data with a fine spatial and temporal resolution has increased in recent years. The requirements for this type of gridded meteorological data fields arise from many different areas of the society, in connection to atmospheric environment studies of air quality and deposition and trends in these parameters, regional climate change, wind energy, hydrological studies etc. The aim of the present project is to investigate the possibility of producing historical, high quality and time consistent, meso-scale re analyses for the whole of Europe regarding precipitation, 2 m temperature and wind for at least 25 years back in time.The MESAN analysis system (Häggmark et al., 2000) at SMHI was chosen as a basis for the reanalysis and the system was adjusted to cover the whole of Europe. In order to find the most appropriate first guess fields to be used in the MESAN system, a pilot study was performed. ERA- 40 data from ECMWF was selected as best possible first guess fields for the re analysis. The performed re-analysis, which is denoted ERAMESAN, includes gridded data covering all Europe with a time resolution of 6 h and a spatial resolution of 0.1º (11 km) in a rotated latitude longitude coordinate system for the time-period 1980-2004. All analyses are archived in GRIB-format and stored on disc at SMHI. The dataset is also available within the EUMETNET optional programme Showcase EUROGRID.A partial validation for the years 1998-2000, using a cross validation procedure with independent observations (5.5% of the total amount of stations), shows an improvement in ERAMESAN compared to the ERA-40 data for all studied parameters with regard to root mean square deviation, mean absolute deviation and mean bias deviation for all seasons. The deviations are roughly of the order of 15% smaller compared to what is obtained from ERA-40. The frequency distribution of large precipitation amounts per day and high wind speeds are substantially better described in ERAMESAN compared to ERA-40. However, the tendency to underestimate the frequency of very large precipitation amounts or high wind speeds, compared to observations, can be seen also for ERAMESAN. It is important to be aware of this limitation when using ERAMESAN data for practical applications concerning evaluation of risks for extreme wind speeds or very large precipitation amounts or in e.g. wind energy studies.

  • 41.
    Jansson, Dick
    SMHI.
    Studier av temperaturinversioner och vertikal vindskjuvning vid Sundsvall-Härnösands flygplats1980Report (Other academic)
  • 42.
    Josefsson, Weine
    SMHI, Research Department, Atmospheric remote sensing.
    Five years of solar UV-radiation monitoring in Sweden1996Report (Other academic)
  • 43.
    Josefsson, Weine
    SMHI, Research Department, Atmospheric remote sensing.
    Measurements of total ozone 1997 - 19992000Report (Other academic)
    Abstract [en]

    A summary of the quality control, quality assurance and measurements of total ozone at Norrköping and Vindeln during the period 1997-1999 is made. The Brewer #006 and Brewer #128 were compared to the travelling reference Brewer #017 at Vindeln in 1999. Major changes in the measurements and instruments are discussed. The reprocessing of all Brewer data since 1996 and the introduction of the new format recommended by WOUDC at the end of 1999 are documented.

    At the end of this three-year period the ozone layer has shown an increase after many years with several periods of considerable depletion. Therefore, the previous downward trend that was as large as -8% per decade has disappeared. The data set consists of 12 years of almost uninterrupted data at Norrköping. Most of the gaps have been possible to fill with satellite data to have monthly values based on a complete set of daily values. An intercomparison between ground based and TOMS Version 7 satellite based data shows an astonishing agreement in most cases.

    Data recorded at Abisko in 1926 and 1927 on the initiative of G.M.B. Dobson was found in the archive. They were recomputed to modem scales and the result shows that the thickness of the ozone layer at that time is similar to the present thickness. The long-term data sets now available from Vindeln and Norrköping give the opportunity to study the temporal and in some respect also the spatial characteristics of the total ozone. Both the spatial correlation and  he auto-correlation vary considerably over time.

    The Web-site for total ozone (under http://www.smhi.se) has made measurements available fora lot of people in almost real-time. Ozone data can be viewed as graphs or transferred by ftp. There are also some pages with general information as well as some links to related sites. In particular, this method for distribution of information has been found to be useful for the public, media and decision-makers.

  • 44.
    Josefsson, Weine
    SMHI, Research Department, Atmospheric remote sensing.
    Solar ultraviolet radiation in Sweden1986Report (Other academic)
  • 45.
    Josefsson, Weine
    SMHI, Research Department, Atmospheric remote sensing.
    Solar UV-radiation monitoring 19961996Report (Other academic)
  • 46.
    Josefsson, Weine
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Karlsson, Jan-Erik
    Measurements of total ozone 1994-19961997Report (Other academic)
  • 47.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    A NOAA AVHRR cloud climatology over Scandinavia covering the period 1991-20002001Report (Other academic)
    Abstract [en]

    A ten-year NOAA A VHRR cloud climatology with a horizontal resolution of four km has been compiled over the Scandinavian region based on results from near real-lime cloud classifications of the SMHl SCANDlA mode!. The frequency and geographic distribution ofthe cloud groups Low-, Medium- and High-level clouds, water and ice clouds and deep convective clouds have been studied in addition to the ten-ycar monthly means of total fractional cloud cover in the region. Furthennore, attempts to estimatc the diurnal cycle of cloudiness and typieal cloud patterns in various weather rcgimes (e.g., North Atlantic Oscillation phases) have been made.

    The cloud climate in the region was found ta be significantly affected by the distribution of land and sea. In particular. the Baltic Sea was shown to suppress summertime cloudiness substantially and this effect was shown to influence cloud conditions in major parts of the Scandinavian region. Huwever, interesting deviations from this cloudiness pattern were found in the Scandinavian mountain range, in the northern part af Scandinavia and over the Norwegian Sea.

    The quality af the satellite-based cloud information was examined by comparing with corresponding surface-observations given by SYNOP-based cloud climatologies for the same period. Results showed good agreement but specific problems were found in winter. In addition, some effects of the degradation of visible AVHRR channels were notieed. Comparisons have also been rnade with internationally used global cloud climate data sets, namely the  SYNOP-based CRU data set and the cloud climatologics from the ISCCP D2 series.

  • 48.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    Cloud classifications with the SCANDIA model1996Report (Other academic)
  • 49.
    Karlsson, Karl-Göran
    SMHI, Research Department, Atmospheric remote sensing.
    Satellite-estimated cloudiness from NOAA AVHRR data in the Nordic are during 19931994Report (Other academic)
  • 50. Kauker, Frank
    et al.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Reconstructing atmospheric surface data for the period 1902-1998 to force a coupled ocean-sea ice model of the Baltic Sea2002Report (Other academic)
123 1 - 50 of 116
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