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  • 1.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Vatten- och materialtransporter mellan bottniska viken och Östersjön1979Report (Other academic)
    Abstract [en]

    Within the framework of the Swedish-Finnish Joint Cornmitte on the Gulf of Bothnia, investigations have been carried out in the Åland Sea and in the Finnish Archipelago Sea in order to study water exchange and transports of heat and nutrients between the Gulf of Bothnia and the Baltic proper. The work has been a cooperation between the Swedish Meteorological and Hydrological Institute (SMHI) and the Finnish Institute of Marine Research. Measurements have been performed by SMHI during the periods June-December 1973, July-December 1974, August 1975-May 1976 and June- August 1977, most intensively in 1974 and 1977. The following parameters have been measured: current speed and direction, water temperature, salinity, oxyge , total phosphorus and total nitrogen.

    The current patterns in the northern part of the Åland Sea are described .An expansion of the north- south current components into empirical orthogonal functions shows the main characteristics of the current systems. The mean circulation during thermally stratified conditions shows southgoing currents in the upper layer and northgoing in the lower. A simple numerical model shows that the main driving force on the net current, when the vertical stratificationis weak, is the surface slope along the channel. Local acceleration and bottom friction are also important.

    Water transports have been calculated from the current measurements.The water exchange is most probably largest during the autumn. In the surnmer of 1977 measurements were made on both sides of Åland. The net transport was southgoing in the Åland Sea (46-95 km3 month- l to the north and 78-236 to the south) and northgoing in the Archipelago Sea (28-44 km3 • month- l to the north and 14-31 to the south) . Comparing the net exchange between the central Baltic and the Gulf of Bothnia with the volume changes in the latter , determined from water level records , gives a difference that probably depends on the choice of representative areas for the current meters. Calculations of transports of total phosphorus, total nitrogen and heat have also been made.

    English translations of captions to figures and tables are found in appendix 11 (the last pages of this report).

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    Vatten- och materialtransporter mellan bottniska viken och Östersjön
  • 2.
    Ambjörn, Cecilia
    et al.
    SMHI, Professional Services.
    Luide, Tiina
    SMHI.
    Omstedt, Anders
    SMHI.
    Svensson, Jonny
    SMHI.
    En operationell oljedriftsmodell för norra Östersjön1981Report (Other academic)
    Abstract [en]

    A model for the forecasting of oil drift has been developed at the SMHI. The model describes the pollution on the surface by treating it as a large nurnberof particles. These particles are transported by:-

    • the surface current driven directly by the wind
    • the background circulation driven by the inclination of the sealevel
    • the turbulence of the sea

    Usually the wind driven current is calculated by reducing the wind speed by a constant factor, the wind factor. Measurements show, however, that the windfactor varies with the state of the oil and also with the wind speed. An equation is derived where the velocity profile decreases logarithmically from the surface downwards and continuously transforms into an Ekman balance at a greater depth.

    The background circulation; the currents driven by the inclination of the sea level, will be calculated by a separate vertically integrated model. The model gives the currents in the Baltic.

    Every oil particle will also be exposed to a turbulent movement, which is calculated by random technics.

    The velocity of each oil-particle can be written as

    \V = \VT + \VB + \V' where

    \VT, is the oil velocity depending on the wind, \VB is the backgroundcirculation and \V' is the turbulent oil movement.

    It is important that this model be fast and easy to handle. At the same time, the results must be reliable and of good quality. The aim is to constantlyhave an effective "emergency forecasting program" ready to operate as soon as an accident occurs .

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  • 3.
    Bathia, PK
    et al.
    IIT Dehli.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Persson, Magnus
    SMHI.
    Application of the distributed HBV-6 model to the upper Narmada basin in India1984Report (Other academic)
    Abstract [en]

    The application of the HBV-6 conceptual runoff model to the Upper Narmada basin is surnmarized. The work includes an extensive investigation of the homogeneity of the precipitation stations anda discussion on the estimates of the potential evapotranspiration. A comparison between a lumped and a distributed model structure is made. Finally is shown how the model can be transformed into a set of nomograms for day-today simulations without support from computer.

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    Application of the distributed HBV-6 model to the upper Narmada basin in India
  • 4.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Development and application of a conceptual runoff model for Scandinavian catchments1976Report (Other academic)
    Abstract [en]

    The experiences of conceptual runoff modelling at the Swedish Meteorological and Hydrological Institute are surnmarized in the present work. The basic philosophy and the methodology when developing the HBV-model are discussed. The structure of the model is described with a discussion of its physical relevance and examples of alternatives. The sensitivity of the model to changes in parameter values is studied through reappings of the response surfaces of a sum of squares criterion of fit. Applications to a variety of catchments in Sweden and Norway are presented and the performance of the model is verified by a numerical criterion of fit, plottings of computed hydrographs and recorded ones, scatter diagrams of peak flows and flow duration curves. Examples of both short range and longrange hydrological forecasting are given.

    A general conclusion is that the HBV-model can be used for the reconstructionof the discharge in catchments of the presented type, if it is properly calibrated. The model can also be used for hydrological forecasting, if combined with meteorological forecasts or recorded climatic series.

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  • 5.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Jönsson, S
    SMHI.
    The application of the BBV runoff model to the Filefjell research basin1976Report (Other academic)
    Abstract [en]

    The application of the model in the Filefjell Basin led us to some conclution concering tho model structure and the relative importance of its parameters.

    The original HBV-2 model had to be modified with the introduction of a third runoff component. A oompletely lumped modifioation proved to be better than a more distributed one.

    Once the model was modiified the calibration was relatively simple.The most important parameters were those in the snow-routine and the recession coefficiants in the responee function. One of the biggest problems when trying to apply the model to ungauged catohments seems to bo the empirical coefficiente that we are forced to use when extrapolating preoipitation observations to areal values.

    The soil moisture routine is less important in this alpine catohment because evaporation is low. A fictive value of the available water, Fc, of 150 mm was assumed but the maximum deficit in the soil moisture zone in the model was less than 50 mm during the seven years in the period.

    The conflict between subjective visual inspection and optimum parameters in the least squares-sense in a strong indication that fittingsoriterious must not be used blindly, unless their capability of representing tbe agreement between tbe observed and computed hydrographs is explored rlgorously.

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  • 6.
    Bork, Ingrid
    SMHI.
    Model studies of dispersion of pollutants in lake Vänern1977Report (Other academic)
    Abstract [en]

    Methods to compute dispersion of pollutants in a known velocity field is described. A Monte-Carlo or random walk technique is used in an example. The velocity field used is two-dimensional, constant in time, but the method can easily be used in a three-dimensional, time dependent velocity field.

    A verification study (e.g. dye outlet in areal water body) is needed to prove the applicabilty of the method.

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  • 7.
    Bork, Ingrid
    SMHI.
    Preliminary model studies of sinking plumes1974Report (Other academic)
    Abstract [en]

    The hydrodynamic equations are reviewed and simplified for use in a study of sinking cooling water plumes. Two examples of observed sinking plumes are shown. A numerical model is employed to study the magnitude of different terms in the equations and the effect of varying turbulent diffusion coefficients. The model is a two dimensional one (one horizontal and one vertical dimension).It is concluded that the sinking phenomena is very sensitive to changes in the vertical diffusion coefficient and it is recomended that future three dimensional studies are carried out in a model containing a reliable computation of the turbulent fluxes .

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  • 8.
    Brandt, Maja
    SMHI, Core Services.
    Sedimenttransport i svenska vattendrag.: Sammanställning och generalisering av data från sedimenttransportnätet.1982Report (Other academic)
    Abstract [en]

    The work with a network for sediment transport in Sweden started in 1966-67. It consists today of about 20 stations in rivers and 6 in small research basins. The following physical water quality parameters are measured: concentration of suspended inorganic and organic matter, concentration of dissolved matter, turbidity, conductivity, colour, pH and water temperature. The transports of suspended and dissolved matter are calculated.

    Characteristic values has been calculated for every station for the quarters of the year and the whole year.

    The effect of climate, different physiography, geology and land use on the physical water quality parameters are exemplified with results from the stations.

    Sweden is divided in eight regions and for every region has guidelines for the different physical parameters and the transport of matter been given.

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    Sedimenttransport i svenska vattendrag. Sammanställning och generalisering av data från sedimenttransportnätet.
  • 9.
    Bringfelt, Björn
    SMHI, Research Department, Climate research - Rossby Centre.
    A forest evapotranspiration model using synoptic data1982Report (Other academic)
    Abstract [en]

    A model giving daily actual evapotranspiration values from synoptic data has been developed using results from the forest meteorological measuring site Velen in southern Sweden. The following submodels are included:

    • Model for evaporation of rain water intercepted by the forest canopy.  Parameters are the free throughfall coefficient and water storage capacity of the canopy. The model was developed using rainfall data from 29 troughs sited below and aside the canopy.
    • Model for transpiration-from the dry forest canopy. A physiological expression for the canopy surface resistance has been developed using 52 daily transpiration values obtained over the canopy by the Bowen ratio-energy balance method.

    Using data from seven synoptic stations during seven warm seasons (April - October) monthly model evapotranspiration sums were compared to monthly data estimated from the hydrological water balance. The agreement was much better than using the traditional Penman formula with synoptic data. Thus,  modelling of the special  forest processes gives significant improvement of the monthly values. The model can now be run for about 190 synoptic stations in Sweden and comparisons can be made with evapotranspiration measurements made in other Darts of the country.

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    A forest evapotranspiration model using synoptic data
  • 10.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    On the spatial representativity of our oceanographic measurements1981Report (Other academic)
    Abstract [en]

    The oceanographic variables measured at and transmitted by the automatic stations are measured in principle at one point. The locations near the body of a lighthouse leeds to the question: "How far from the point are the values valid?" and "How do the variables vary in the surroundings of the station?"

    A straight-forward study was made. At several locations along a section out from the lighthouse temperature, salinity and currents were measured. The results from this study are presented.

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    On the spatial representativity of our oceanographic measurements
  • 11. Eggertsson, L E
    HYPOS Ett system för hydrologisk positionsangivelse1980Report (Other academic)
    Abstract [en]

    A hydrological positioning system (HYPOS ) which organizes the geographical locations of lakes and river networks has been developed at the Swedish Meteorological and HydrologicalInstitute (SMHI).

    System parameters fora point are:

    River/lake outlet co-ordinatesPosition co-ordinatesDistance from outlet (along a river skeleton line or a polygon)Hydrological codeName of river/lake

    The central line of a river is described by a skeleton line.Lakes, coasts, catchment areas and islands are described as polygons.

    Every line or polygon is linked toa superior line or polygon using outlet points and linkpoints.

    A forking and its source are linked to a secondary outflow point, intermediate point and inflow point. An arm and its source are linked in the same way.

    Points in a river are sorted with ascending distance from outlet. Main rivers and tributaries are sorted as follows: Main rivers,most downstream tri butary (A), tributaries to A, second mostdownstream tributary (8), tributaries to Band so on.

    The system is stored on magnetic disc and consists of two file sSkeleton and Countour File and Index File.

    The determination of the position is made in two steps. First the Index File is scanned. That results in a number of possible records in the Skeleton and Countour File. Secondly the possible records are carefully scanned.

    The system has been tested on the rivers Tidan and Eskilstunaån.

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    HYPOS Ett system för hydrologisk positionsangivelse
  • 12.
    Engqvist, Anders
    et al.
    SMHI.
    Svensson, Jonny
    SMHI.
    Water turnover in Himmerfjärd 1977 - a simulation study1984Report (Other academic)
    Abstract [en]

    A two-dimensional circulation model (one vertical, one horizontal axis) was validated for a 3-week period, taking place in early fall 1977. For this time there exists independent measurement-based estirnates of the water turnover in Himmerfjärd estuary. Indata (forcing) of the model are: N/S-component of the wind velocity, fresh water flow, changes in water level and salt and temperature changes at the model border towards the Baltic. The validated model was run with the same parameter set-up for four other 3-week periods, distributed over the year 1977 to cover the different main circulation modes. Disregarding the simulation of winter situation with ice, the results seem reasonable. By the aid of a hypermodel the results of these runs were interpolated to encompass a first coarse but approximately correct whole-year estimate of the water transport in the sounds adjacent to Himmerfjärd's inner basin during 1977.

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    Water turnover in Himmerfjärd 1977 - a simulation study
  • 13.
    Eriksson, Bertil
    SMHI.
    Den "Potentiella" evapotranspirationen i Sverige1981Report (Other academic)
    Abstract [en]

    Some critical remarks regarding the concept of "potential" evapotranspiration are quoted. In spite of this daily values of "potential" evapotranspiration have been calculated for a lot of Swedish weather stations. Two different formulas have been used, the one by Penman and another one given by W Johansson. he global radiation is estimated with the aid of observations of cloud amounts. Different values of the albedo is tested. During winter time, when the ground is covered by snow, a high value of the reflexion coefficient is used.

    The results presented are monthly and annual means för the period 1961-78. The formulas used are valid neither for evaporation from forests nor from snow cover. But the results found seem to be rather reasonable. During winter the mean values are very close to Zero, when the interception losses from forests are high the formula by Penman gives too low values.

    The mean annual values found for Sweden amount to 500-600 mm in the southern parts, 300-500 in the northern parts.

    The 2potential" evapotranspiration values calculated have been compared with precipitation sums for the year, the growing season and for the summer months. The "potential" precipitation deficits have their highest values in the eastern parts of the south of Sweden.

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    Den "Potentiella" evapotranspirationen i Sverige
  • 14.
    Eriksson, Bertil
    SMHI.
    Sveriges vattenbalans Årsmedelvärden 1931-60 av nederbörd, avdunstning och avrinning1980Report (Other academic)
    Abstract [en]

    The correction factors , which were proposed in anearlier 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 conclusionis drawn that the corrections of the precipitation data have the correct order of magnitude. However, there are of course great uncertainties int he 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 stationsare too few in higher regions. For the country as awhole is found that somewhat less than 50% of the precipitationevaporates as water vapour into the atmosphere .In mountanious regions, where the largest precipitation amounts fall, only about 15% dissapear into the air.

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    Sveriges vattenbalans Årsmedelvärden 1931-60 av nederbörd, avdunstning och avrinning
  • 15.
    Fremling, S
    SMHI.
    Sjöisars beroende av väder och vind, snö och vatten1977Report (Other academic)
    Abstract [sv]

    I föreliggande skrift sammanfattas en del kunskaper, som inhämtats vid SMHI, hydrologiska byråns isavdelning, och som vidgats genom litteraturstudier. Den kvantitativa utvärderingen av olika faktorers betydelse för sjöisars tillväxt och avtagande har ägnats särskilt intresse.

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  • 16.
    Fremling, S
    SMHI.
    Sjöisars bärighet vid trafik1977Report (Other academic)
    Abstract [en]

    THE BEHAVIOR OF LAKE ICE UNDER RAPIDLY INCREASINGSTATIONARY LOADS

    I.A. Radial cracks on bottom of ice

    A brief account of ´Deflections of an infinite plate', 1950 by Wyman is given here. Wymans expression of the maximum tensile stress, when the loading is uniform. over a circular area, has been expressed in the form of (I:4). The 'characteristic length', L, is plotted against the ice thickness, h, in fig I:2 and the 'load index', c (= P/h2 ) is plotted against the 'relative load radius', 'T'(= r/L) in fig I:3. When T = 0,6 kei' T/T: can be approximated by½(0,6159 - lnT). By inserting this expression the formula (I:4) is identical to Westergaard's formula given in 'Stresses in concrete pavements computed by theoretical analysis', Publ.Roads Vol. 7 nr 3, 1926.

    I.B. Ring-cracks and break-through

    This chapter gives a summary of 'The narrow free infinite wedge on an elastic foundation', 1961 by Nevel. Nevels expression of the maximum tensile stress is here given in the form of (I:8). Fig I:7 shows cR-values for various 'T-values = 0 ,6. Nevel writes: ".... the wedge of the crack ed ice sheet will be able to carry more load than predictedby the free wedge model."

    The break-through-load is here computed from formula(I:10) by B Persson. Fig I:7 shows cB-values for various "T-values. Table I:l gives numerical examples.

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  • 17.
    Funquist, Lennart
    SMHI, Research Department, Oceanography.
    En inledande studie i Vätterns dynamik1979Report (Other academic)
    Abstract [en]

    Continuous current and temperature data were taken from one station in Lake Vättern during the 1977 surnrner. Further temperature data were collected from two stations by continuous recordings at eleven depths during a fortnight period.

    A three-dimensional hydrodynamic model has been applied to the lake. Observations of current and temperature show a good agreement with corresponding model results.

    Wave like motions have been studied through a method of rotary spectral analysis. It is suggested tha tobserved waves can be related to different modes of Poincaré waves. Motions with a period of several days were observed and have been interpreted in terms of internal Kelvin-waves. There also is evidence of motions with a frequency lower than the inertial value pointing towards nonlinear interactions between inertial motions and lower frequency currents.

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  • 18.
    Funquist, Lennart
    et al.
    SMHI, Research Department, Oceanography.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    A model for pollution studies in the Baltic Sea1984Report (Other academic)
    Abstract [en]

    A combination of a circulation anda diffusion model has been developed to be used for dispersion studies in the Baltic Sea. As the time scale of interest is from months up to several years a straightforward way to model the dispersion would require the circulation model to be run for a very long time, which would be impractible. Instead atypical meteorological year has been constructed for which the circulation model has been run. The circulation model is three-dimensional, uses six layers in the vertical and hasa horizontal resolution of 10 kilometres. The diffusion model is of Monte Carlo type in all three dimensions. So far only passive pollutants have been treated but the model will be extended to include biochemical interaction and sedimentation processes. Results of applications to three outlets are shown.

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    A model for pollution studies in the Baltic Sea
  • 19.
    Gidhagen, Lars
    SMHI, Research Department, Air quality.
    Coastal upwelling in the Baltic - a presentation of satellite and in situ measurements of sea surface temperatures indicating coastal upwelling Part l and ll1984Report (Other academic)
    Abstract [en]

    Satellite data (AVHRR) and in situ data of sea surface temperatures have been used to describe wind-induced upwelling along the Swedish coast of the Baltic.

    The satellite data, transformed to isotherm charts  points out three sections of the coast where the upwelling is especially intense. The cold upwelled water, normally found within 10 - 20 kilometres from the coast, sometimes spreads out in finger-like filaments. There are indications of propagation of upwelling fronts and centers, which may be associated with coastal-trapped waves. .

    Ten years of insitu measurements of sea surface temperature have been used for a statistical compilation of upwelling events. The statistics reveal that upwelling is a common feature along certain sections of the coast, occuring for about one fourth to one third of the time. Some information of time- scales and temperature anomalies associated with the upwelling events are also given. A wind analysis shows a correlation between upwelling and winds parallell to the shoreline, in accordance with the Ekman theory of upwelling generation.

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    Coastal upwelling in the Baltic - a presentation of satellite and in situ measurements of sea surface temperatures indicating coastal upwelling Part l
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    Coastal upwelling in the Baltic - a presentation of satellite and in situ measurements of sea surface temperatures indicating coastal upwelling Part ll
  • 20.
    Gottschalk, Lars
    et al.
    SMHI.
    Jutman, Torbjörn
    SMHI, Core Services.
    Statistical analysis of snow survey data1979Report (Refereed)
    Abstract [en]

    Spatial variation of snow cover in Sweden has been very little studied up til now. This is quite remarkable as snow plays a predominant role in runoff formation in the whole of Sweden. In operational practice today the snow cover is calculated as accumulated precipitation for periods with temperatures below zero. Errors of snow measurements from precipitation gauges are very large and that is why the accumulated precipitation gives only rough estimates of the actual snow cover. Snowmelt periods during winter make it necessary to include a snowmelt procedure into calculations, which introduces a further source of uncertainty. Snowdepths are measured in connection with precipitation measurements but are not completed by information about water content, so important for hydrologists. The present practice can give acceptable results in certain regions with stable climate conditions and forests i e in the woodlands of Norrland. For other parts of Sweden i e for the mountain region and the south of Sweden the present practice is doubtful.

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    Statistical analysis of snow survey data
  • 21.
    Gottschalk, Lars
    et al.
    SMHI.
    Krasovskaia, Irina
    SMHI.
    Synthesis, processing and display on comprehensive hydrologic infromation1980Report (Other academic)
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    Synthesis, processing and display on comprehensive hydrologic infromation
  • 22.
    Jutman, Torbjörn
    SMHI, Core Services.
    Stationsnät för vattenföring i Sverige1981Report (Other academic)
    Abstract [en]

    A strategy for the runoff network is developed. Measures of runoff variability in space and time together with demands from users of data have been considered.Varying demands on the network made it necessary to divide the stations into three categories:

    1. Stations in rivers influenced by regulations.

    2. Stations in rivers uninfluenced by regulations, drainage are < 100 km2.

    3. Stations in rivers uninfluenced by regulations, drainage area> 100 krn2.

    Approximately one half of the total nurnbers of stations belong to the first category. Rather few stations were suggested to be added to this category, the additional stations mainly for environmental control purposes.Stations in small, natural rivers (second category) need to be water balance stations. This is due to the strong dependence of the physiography of the basin and local neteorological factors. l.ocations of water balance stations will be chosen according to a stratified sampling procedure. A map of hydrologic regime regions has been cornbined with a map showing a subdivision in natural geographic regions.

    A method presented by Karasseff is used for the third category. Statistical measures of runoff variability have been compared with different types of errors involved to give network density.

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    Stationsnät för vattenföring i Sverige
  • 23.
    Omstedt, Anders
    SMHI.
    A forecast model for water cooling in the Gulf of Bothnia and lake Vänern1984Report (Other academic)
    Abstract [en]

    A new forecasting model for water cooling in the Gulf of Bothnia and Lake Vänern is presented. The model elements consist of a transient Ekman model, where the turbulent exchange coefficients are calculated with a two-equation model of turbulence, a heat flux package for calculating the net heat loss at the air/sea interface, and geometries based upon area/depth distributions for the Bothnian Bay, the North Bothnian Sea, Lake Vänern/Dalbosjön, and Lake Vänern/Värmlandssjön.

    The model system can handle up to five different forecasts of maximum 30 days each simultaneously. It is constructed for easy and rapid interactive handling by letting the forecaster answer questions on a terminal screen.

    During the winter navigation period of 1983/84 the model was tested in routine. The results from that test period were most satisfactory, and it is believed that the new forecasting model can serve as a reliable adviser for effective winter navigation planning during coming seasons.

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    A forecast model for water cooling in the Gulf of Bothnia and lake Vänern
  • 24.
    Omstedt, Anders
    SMHI, Research Department, Oceanography.
    An investigation of the crystal structure of sea ice in the Bothnian Bay1985Report (Other academic)
    Abstract [en]

    This report presents sea ice core measurements taken from the Bothnian Bay, March, 1984. The measurements were taken at different sites in the skerries and the basin area. The ice cores were analysed with respect to crystallographic structure using polarized light. Some ice cores were also used for the determination of ice density and ice salinity. The data give a good insight into the ice structure in a sea ice cover, illustrating a complex structure with ice types of different origins, mixed and stratified within the ice cores.

    The ice cores were classified with a structural scheme. In that scheme, the sea ice is classified into three main groups: granular ice, columnar ice and mixed ice. In the examined ice cores all three groups were well represented.

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    An investigation of the crystal structure of sea ice in the Bothnian Bay
  • 25.
    Omstedt, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Vertical mixing and restrafication in the bay of Bothnia during cooling1982Report (Other academic)
    Abstract [en]

    Autumn cooling in the Bay of Bothnia provides an opportunity for studying wind mixing, convection and restratification below the temperature for maximum density. Vertical temperature profiles for a 52 day period are analysed for the case of cooling of brackish sea water around the temperature of maximum density. A mathematical model, which is based on the conservation equations for momentum, heat and salt in their one- dimensional form and with an equation of state which is linear with respect to salinity but quadratic with respect to temperature, is presented. Turbulent exchange coefficients are calculated with a kinetic energy- dissipation model of turbulence.

    Due to the fact that both salinity and temperature effect stratification and that buoyancy flux changes signat the temperature for maximum density several processes influence the cooling rate. The mathematical model describes these and the general development of the temperature profiles in a most satisfactory way.

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  • 26.
    Simons, T. J.
    et al.
    SMHI.
    Funquist, Lennart
    SMHI, Research Department, Oceanography.
    Svensson, J
    SMHI.
    Application of a numerical model to lake Vänern1977Report (Other academic)
    Abstract [en]

    Current, temperature and water-level measurements in Lake Vänern from two epdisodes in 1971, representing a stratified resp anunstratified situation, have been used for the verification of an multilayer hydrodynamic model. Concentrating on wind-driven lake circulation it is shown that, aside from the currents along the western shore of the eastern basin, the correspondence between model results and observations is satisfactory. The computed currents could therefore be used for studies on the transport and dilution of wasterwater in the lake. It is also concluded that neither avariation of model parameters nor an increased vertical or horizontal resolution will make the model reproduce the strong and mainly south-going current along the western shore of the eastern half of the lake.

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  • 27.
    Svensson, J
    SMHI.
    Beräkning av effektiv vattentransport genom Sunninge Sund till Byfjorden1975Report (Other academic)
    Abstract [en]

    Current measurements were carried out at three depths on asite in the mouth of Byfjorden on the west coast of Swedenduring parts of 1971 and 1972. The record from 1972 has been filtered so that fluctuations with periods about 12 hrs and less have been damped out. The transport has been computed from the remaining current. The net transport has also been computed from water level fluctuations in the fiord. Comparison between the two computed net transports shows that depending on the wind speed and direction one gets different agreement between the values and the difference is at times bigger than the value itself, The transport values in the different layers are however orders of magnitude higher than the net transport and it is believed that the effective transports in the different layers have been well estimated by this computation. The work has been coupled to a tracer study.

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    BERÄKNING AV EFFEKTIV VATTENTRANSPORT GENOM SUNNINGE SUND TILL BYFJORDEN
  • 28.
    Svensson, J.
    SMHI.
    Calcultation of poison concentrations from a hypothetical accident of the Swedish coast1975Report (Other academic)
    Abstract [en]

    A model is developed by which the poison concentration due to a discharge of toxic matter in the coastal water is calculated. The outlet arises from a hypothetical accident to a ship loaded with dangerous materials. The oceanographic conditions are assumed to be mast unfavourable for a rapid dilution of the toxic matter and the current is assumed to be towards the coast. Calculations of the time development ,as well as calculetion is of areas constantly covered with :poison during a time·period of 45-55 hours are carried out for different conditions.

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  • 29. Svensson, Jonny
    Seminars at SMHI 19760329-0401 on numerical models of the spreading of cooling-water1976Report (Other academic)
    Abstract [en]

    A model was developed by Prych (1972) at SMHI for thermal pollution predictions. The model, which is a modified version of a model originally presented by Stolzenbach and Harleman (1971), is based on an integral analysis of a turbulent, bouyant, horizontal, surface jet into a large ,deep, uniform, turbulent, flowing, ambient water body. In the analysis similarity functions are assumed for the temperature and velocity distributions in the cross section of the jet flow. An attempt to verify, or test the accuracy of the model was done by Weil (1974) at SMHI with eight sets of data from a Swedish power station and data from two plants on Lake Michigan in the United States.

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  • 30.
    Svensson, Jonny
    SMHI.
    Vågdata från svenska kustvatten 1979-19801981Report (Other academic)
    Abstract [en]

    Wave rneasurernents have dluring 1979-80 been carried out at four sites at the Swedish coast.

    Plottings of wave and wind data, monthly mean significant wave hight and wave power as function of wave period are presented.The duration of storms and of calrn periods is also computed as well as scatter diagrams (wave hight versus wave period, wave power versus wave period).

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    Vågdata från svenska kustvatten 1979-1980
  • 31.
    Svensson, Jonny
    et al.
    SMHI.
    Wilmot, Wayne
    SMHI.
    A numerical model of the circulation in Öresund. Evaluation of the effect of a tunnel between Helsingör and Helsingborg.1978Report (Other academic)
    Abstract [en]

    This report is to describe the application of a previously developed two-dimensional hydrodynamic numerical model (W.Wilmot 1976) to Öresund between Sweden and Denmark. The purpose of this application is to investigate the effect of a proposed tunnel connecting Helsingborg in Sweden and Helsingör in Denmark on the circulation and salinity content of the Sound.

    The model resul t is first compared with synoptic field data from the Sound. The effects of the proposed tunnel are investigated by comparing model results with and without the tunnel.

    The tunnel between Helsingör and Helsingborg is planned to be built partly below the bottom, but partly on an artificial bank across the deeper part of the Sound. The exact position of the tunnel has not yet been decided . Among the different proposals given, this report concerns only the situation which gives the maximum change in the sectional area compared to the natural case.

    Three alternative depths are given for the tunnel. The main proposal is a distance from the free surface to the roof of the tunnel of 24 m. Also the depths 28 m and 20 m can be considered.

    The sill depth through Öresund into the Baltic Sea is about 8 m and the  unnel is therefore not considered to change the water exchange between the Baltic and the North Sea. However, south of the planned tunnel (see fig 1) there are areas with depths of 30 m and more. The circulation and salinity of these areas are studied in the model with various external conditons.

    The same study has also been carried out in a two-layer numerical model (Danish Hydraulic Institute 1977) and to a limited extent in a channel model including an advanced turbulence description (Technical High School, Lund 1976). The ultimate result from the hydrodynamic model studies has been the basi sof an ecological model and other ecological considerations (Vandkvalitetsinstitutet 1976).

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  • 32.
    Svensson, Sören
    SMHI.
    A statistical study for automatic calibration of a conceptual runoff model1977Report (Other academic)
    Abstract [en]

    A conceptual runoff model is studied in this work. Especially the residuals of the model (the differences between the computed hydrograph and the recorded one) are examinated. The density function and the autocorrelation function of the residuals are estimated and tested.

    The model must be calibrated for each new catchment, to which it is applied. Therefore a criterion of the goodness of fit between the computed and the recorded hydrograph is required. Some criteria of fit have been examined concerning their sensitivity to changes in the model parameter setting.

    Conclusions of the work are: The residuals of the model are neither stationary nor independent and normally distributed. A classification based on the different physical processes, which govern the discharge, makes the residuals of each class more stationary and in some sense more normally distributed than the residuals of the material without any classification. Furthermore a criterion of goodness of fit, based on the classification above resembles the subjectively judged fit more than the simple sum of squares criterion, which has become practice in applications of runoff models.

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  • 33.
    Udin, Ingemar
    et al.
    SMHI.
    Mattisson, Ingemar
    SMHI.
    Havsis- och snöinformation ur datorbearbetade satellitdata. En metodstudie1979Report (Other academic)
    Abstract [en]

    Computer programs have been developed for handling of NOAA VHRR digital data. The programs include geometric corrections, presentation of calibration data, derivation of data, variation of grey scales, different presentationforms etc. A SAAB D23 computer has been used for the computations. Line printer has mostly been used for presentation of data, but also electrostatic plotter and inkjet plotter have been used. The analogue VHRR data was digitizedat the Swedish Defense Research Board.

    The software has mainly been applied to sea ice and snow studies but also in a less degree to studies of sea surface temperature and examination of data, which was supposed to be the oil spill at platform Bravo in the Ekofisk area.

    Digital processed satellite data are more useful than photographic pictures both for sea ice and snow mapping. Quantification of snow cover and some ice parameters is possible, but for many purposes a multispectral data analysis is necessary in order to avoid false information.

    A short sea ice study with computer processed LANDSAT data has also been carried out. The soft ware used was developed at the Swedish Defense Research Board.

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    Havsis- och snöinformation ur datorbearbetade satellitdata. En metodstudie
  • 34. Vasseur, B.
    Modifying a jet model for cooling water outlets1979Report (Other academic)
    Abstract [en]

    A modification of Prych's mathematical model (1972) for predicting the spreading of cooling water froma surface outlet is presented. The main modifications area change in the calculation of the initial values after the zone of flow establishment, more realistic density calculations and the introduction of the fact that spreading of the jet's heat content takes place faster than the spreading of its velocity .

    In the modified model the calculated plumes are noticeably narrower and thicker than in Prych's model. Furthermore, the jet's deflection by the ambient current is stronger and excess temperature on the surface diminishes faster.

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    Modifying a jet model for cooling water outlets
  • 35.
    Vasseur, B.
    SMHI.
    Temperaturförhållanden i Svenska kustvatten1975Report (Other academic)
    Abstract [en]

    This report is an attempt to describe natural temperature variations around the Swedish coast. The data are collected partly from Swedish and Danish lightship observations, partly from measurements made by SMHI observers and recording instruments. The observational stations are concentrated around the southern coast of Sweden, which leaves the Gulf of Bothnia somewhat under-represented,

    For comparison of large scale temperature variations in the different areas during different years, monthly mean temperature values during the years 1924-39 from several lightships around Sweden have been calculated. A geographical distribution has been made from the yearly cycle and certain features in the different areas have been established. Furthermore an attempt has been made to characterize the years during the period 1923-70 as warm or cold in an oceanographic sense and briefly evaluate the causal relations.

    In order ta campare the "temperature shocks" caused by cooling water discharges with natural temperature variations, the maximum temperature variations during 1, 6 and 24 hours at different depths have been calculated. Temperature conditions along the Swedish coast have been studied by producing statistics of the thermocline´s strength and depth during different months and for different places.

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  • 36.
    Vasseur, B
    et al.
    SMHI.
    Funkquist, Lennart
    SMHI, Research Department, Oceanography.
    Paul, J F
    SMHI.
    Verification of a numerical model for thermal plumes1980Report (Other academic)
    Abstract [en]

    As apart of a research project, financially supported by the CDL, to study the thermal effects of waste heat discharged into natural water recipients, this report describes a numerical model for this purpose anda number of verifications against real data.

    The model is based on the conservation laws for mass momentum and energy. It is time-dependent, three-dimensional and has the possibility of using a varying horizontal resolution depending on the nature of the problem.

    A coordinate transformation in the vertical direction gives the model the same number of calculating points in the vertical all over the modelled area, which increases the confidence in the vertical description considerably. This is of great value, as most of the discharges and the pollution problems are in shallow areas, where other medels in general will have a poor resolution.

    Applications of the model to different types of recipients are presented and the effects of important mixing mechanisms are illustrated. The model results have been verified against field measurements, and important plume characteristics like area of heated surface water, vertical extent of the plume,and centerline temperature decay have all been successfully simulated. The verification study demonstrates in addition that recirculation of cooling water is well described by the model.

    The verification studies suggest enlarged use of this type of model studies both in the planning of new locations for power plants and in the monitoring of the environmental effects of the discharged heat.

    This model can be used both to predict thermal effects in the immediate neighbourhood of the power plant and to predict distribution and long term variations in wider surroundings. Of special interest is the use of the model when locations of the inlet and outlet are to be considered.

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    Verification of a numerical model for thermal plumes
  • 37.
    Weill, James G.
    SMHI.
    Verification of heated water jet numerical model1974Report (Other academic)
    Abstract [en]

    Reported are diverse efforts to verify, or test the accuracy of,a numerical model for thermal pollution predictions. The model,developed by Prych (1972) at SMHI, is an integral analysis ofa buoyant, turbulent surface jet. The program. is slightly revised,and effects of the changes are presented.

    Numerical model results are compared directly with ten prototype situations: eight sets of data from a Swedish power station on the coast of the Baltic Sea, and data from two power plants on Lake Michigan in the United States. A few direct comparisons are made with a laboratory model of the Swedish plant and with laboratory data for momentumless surface jets. To minimize coastal effects, a scheme is presented for interfacing then umerical model with undistorted laboratory model results.

    The discharge situation is described nondimensionally, and numerical experiments are made to determine the sensitivities of jet temperatures to input variables. Results are compared with phenomenological and analytical models. In addition to the main verification effort, investigations are made concerning methods of field data collection.

    Conclusions are presented for direct application and for relative or comparative use of the numerical model.

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    VERIFICATION OF HEATED WATER JET NUMERICAL MODEL
  • 38.
    Wilmot, Wayne
    SMHI.
    A numerical model of the effects of reactor cooling water on fjord ciculation (I)1976Report (Other academic)
    Abstract [en]

    In the search for possibie sites for new nuclear power plants in Sweden a site on Bråviken, a narrow fjord, is being considered. A numerical hydrodynamic model has been developedt o predict the probable effects of the waste heat discharged into the estuary on the natural estuarine flow.

    The model employs the basic equations of motion and conservation of salt and heat with appropriate approximations to make predictions. The primary approximation in the model consists of considering the estuary as a channel in which cross channel effects do not explicitly appear. The along channel motion is thus primary determined by the along channel density gradients.

    A number of different cases have been investigated. The basic states in the summer and in the winter have been established in order to evaluate effects of heated water in two different conditions of thermal stratification . For each of these seasons two different intake configurations have been considered: a surface intake and a bottom intake. The outlet is located at thesurface. The above situations have been considered for several wind conditions: no wind, a 5 m/s constant wind bending to transport water in to the estuary, and a 12 m/s time dependent wind which gradually builds up blowing out of the estuary, changes direction and then dies away. A series of experiments with various runoff values at the head of the fjord have been conducted.

    With the construction of a bottom intake located at the depth of about 40 meters there will be little noticable effect on the circulation, temperature or salinity fields in the estuary in the summer. However in the winter the bottom intake offers only a partial improvement over a surface intake. During the winter the heated water would cause changes of as much as 50 % in the natural state. The surface intake would cause changes which sometimes are almost twice as big. The problem arises because the10°C heated water creates sizable horizontal density gradients which are sufficient to counteract the weak natural flow .

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