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  • 1.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Carlsson, Bengt
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Pettersson, Anna
    SMHI, Research Department, Hydrology.
    Rummukainen, Markku
    SMHI, Research Department, Climate research - Rossby Centre.
    Climate change impacts on runoff in Sweden - assessments by global climate models, dynamical downscaling and hydrological modelling2001In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 16, no 2, p. 101-112Article in journal (Refereed)
    Abstract [en]

    The Swedish regional climate modelling programme, SWECLIM, started in 1997 with the main goal being to produce regional climate change scenarios over the Nordic area on a time scale of 50 to 100 yr. An additional goal is to produce water resources scenarios with a focus on hydropower production, dam safety, water supply and environmental aspects of water resources. The scenarios are produced by a combination of global climate models (GCMs), regional climate models and hydrological runoff models. The GCM simulations used thus far are 10 yr time slices from 2 different GCMs, UKMO HadCM2 from the Hadley Centre and the ECHAM4/OPYC3 of the Max Planck Institute for Meteorology. The regional climate model is a modified version of the international HIRLAM forecast model and the hydrological model is the HBV model developed at the Swedish Meteorological and Hydrological Institute. Scenarios of river runoff have been simulated for 6 selected basins covering the major climate regions in Sweden. Changes in runoff totals, runoff regimes and extreme values have been analysed with a focus on the uncertainties introduced by the choice of GCM and routines for estimation of evapotranspiration in the hydrological model. It is further shown how these choices affect the statistical return periods of future extremes in a design situation.

  • 2.
    Bergström, Sten
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Graham, Phil
    SMHI, Professional Services.
    Gardelin, Marie
    SMHI, Professional Services.
    Climate change impacts on the hydrology of the Baltic Basin.2001In: Proceedings of the third study conference on BALTEX / [ed] J. Meywerk, 2001, p. 17-18Conference paper (Other academic)
  • 3.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Sandén, Per
    SMHI.
    Gardelin, Marie
    SMHI, Professional Services.
    Analysis of climate-induced hydrochemical variations in till aquifers1990Report (Other academic)
    Abstract [en]

    An investigation of the relations between climatological factors and short term variabilityin groundwater storage and hydrochemistry in till aquifers is performed. The analysis isbased on a simple empirical hydrological model, the PULSE model, and groundwaterrecords from four sites in Sweden.The model proved to be capable of describing the dynamics of groundwater levels ordischarge, and at one of the sites it was possible to describe hydrochemical variations aswell. The application to the remaining three sites illustrated that groundwater chemistryshows a much more complex pattem of variations than does corresponding streamflowin this type of basin. The importance of areal variabilities within the recharge area isdiscussed and illustrated by a distribution of the model into two submodels when applyingit to one of the basins.

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  • 4.
    Brandt, Maja
    et al.
    SMHI, Core Services.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    MODELING THE EFFECTS OF CLEARCUTTING ON RUNOFF - EXAMPLES FROM CENTRAL SWEDEN1988In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 17, no 5, p. 307-313Article in journal (Refereed)
  • 5.
    Brandt, Maja
    et al.
    SMHI, Core Services.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Modellberäkning av extrem effektiv nederbörd1987Report (Other academic)
    Abstract [sv]

    Följande analys av vattenbalansen vid extrema situationer är ett led i Flödeskommittens arbete med att ta fram nya riktlinjer för dimensioneringsberäkningar för dammar och utskov, som inleddes våren 1985 (Ehlin, 1986). Frågan fick förnyad aktualitet i samband med höstflöden 1985 och 1986, som orsakade översvämningar och ett antal mindre dammras.De viktigaste faktorerna för beräkning av dimensionerande flöden är arealnederbörd, snösmältning, markfuktighet samt flödessituationen före flödet. En analys av extrem nederbörd har utförts (Vedin och Eriksson, 1986). För beräkning av effekten av den extrema nederbörden på flödet behöver även kombinationer av eventuell snösmältning och markfuktighetsunderskott i marken vara kända. Hur stor snösmältning kan tänkas ske i ett avrinningsområde? Kan vi räkna med att marken är helt mättad? Ett sätt att analysera detta är att med HBV-modellen ta fram extrema arealnederbörds- och snösmältningsvärden samt lägsta  markfuktighetsunderskott. I denna rapport redovisas en analys, som bygger på HBV-modellberäkningar i tjugofem avrinningsområden. Sammanlagt täcker områdena 79 000 km2 av Sveriges totala yta på449 000 km2. Den sammantagna tidsperioden för beräkningarna är475 år.

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  • 6.
    Eklund, Anna
    et al.
    SMHI, Core Services.
    Gardelin, Marie
    SMHI, Professional Services.
    Lindroth, Anders
    SMHI.
    Vinteravdunstning i HBV-modellen - jämförelse med mätdata2000Report (Other academic)
    Abstract [sv]

    Avdunstningen är den del i vattenbalansen som är minst känd på grund av att den är svår att mäta. Minst studerad är avdunstningen vintertid. I denna studie har avdunstningsmätningarfrån Norunda, norr om Uppsala, använts för de fem vintrarna 1994/1995 till 1998/1999. Mätningarna har utförts inom NOPEX-projektet (Northern Hemisphere Climate-processes Land-surface Experiment). Den beräknade avdunstningen i HBV-modellen har jämförts med dessa mätningar för att få en uppfattning om den modellberäknade avdunstningens kvalitet. För beräkning av avdunstningen i HBV-modellen används främst två olika metoder, dels avdunstning beräknad med Penmans formel, dels temperaturberoende avdunstning enligt Thornthwaites metod. En rad olika varianter av dessa båda metoder har testats i simuleringar med HBV-modellen, t.ex. avdunstningsberäkningar med och utan interceptionsmagasin.

    Den uppmätta avdunstningens storlek och variation är i stort sett likartad under de olika vintrarna trots att vintrarna haft mycket olika karaktär. De fyra första vintrarna var avdunstningens dygnsmedelvärde från oktober till mars mellan 0,20 och 0,24 mm. Det sker en betydande avdunstning även vid tillfällen då marken är snötäckt, i medeltal 0, 15 mm/dygn.

    Tidigare har man antagit att HBV-modellen underskattar avdunstningen under vintern. Man har i modellberäkningarna tvingats att korrigera snönederbörden med en faktor ner till 0, 7 för att få vattenbalansen att stämma. De jämförelser som här gjorts mellan uppmätt och beräknad avdunstning visar dock att man i de flesta fall i detta område inte gör någon underskattning av vinteravdunstningen. Av de metoder som idag används för att beräkna avdunstning ger Penman-ETF bättre resultat än Thornthwaitemetoden. Införandet av ett interceptionsmagasin till Penman-ETF-simuleringen ger en förbättring av vinteravdunstningen.

    Det är svårt att göra några generella förändringar av avdunstningsberäkningarna i HBVmodellen baserat på denna studie, eftersom de slutsatser som dragits vid denna undersökning endast gäller för vinterperioden i Norunda. Nya rutiner för avdunstningsberäkningarna bör även grundas på studier av avdunstningen under övrig tid av året, det vill säga den period då avdunstningen har betydligt större inverkan på vattenbalansen. Visst samband har påvisats mellan avdunstningen vintertid och ångtrycksdeficit. Försök bör göras att inkludera denna variabel i avdunstningsberäkningarna i HBV-modellen.

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  • 7.
    Gardelin, Marie
    et al.
    SMHI, Professional Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Priestley-Taylor evapotranspiration in HBV-simulations1997In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 28, no 4-5, p. 233-246Article in journal (Refereed)
    Abstract [en]

    Estimations of potential evapotranspiration as input to runoff calculations with the HBV model are usually given as monthly standard values calculated with the Penman method. Daily changes in the weather conditions can in later model versions be taken into account by the introduction of a temperature anomaly correction of the evapotranspiration. In this study daily values of potential evapotranspiration calculated with the Priestley-Taylor method were used as input to the model. The required net radiation estimations were calculated from routine weather observations including cloudiness. Potential evapotranspiration was calculated on a three hour basis over a 20-year period. Model simulations using different input data on the potential evapotranspiration were made for three drainage basins (3,500-4,300 km(2)) in Sweden. The Priestley-Taylor evapotranspiration generally gave small improvements of the runoff simulations. The simple temperature anomaly correction method gave improvements of the same size.

  • 8.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Johansson, Barbro
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    HBV-96 – En areellt fördelad modell för vattenkrafthydrologin1996Report (Other academic)
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  • 9.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Conceptual modelling of evapotranspiration for simulations of climate change effects1994Report (Other academic)
    Abstract [en]

    The evapotranspiration routines in existing conceptual hydrological models have been identified as one of the weaknesses which appear when these rnodels are used for the simulation of hydrological effects of a changing clirnate. The hydrological models in operational use today usually have a very superficial description of evapotranspiration. They have, nevertheless, been able to yield reasonable results. The objective of this paper is to analyse and suggest modifications of existing evapotranspiration routines in conceptual hydrological models to make them more appropriate for use in simulation of the effects of a changing climate on water resources.

    The following rnodifications of the evapotranspiration routine were formulated and tested in the HBV model: Ternperature anomaly correction of evapotranspiration, potential evapotranspiration by a simplified Thornthwaite type formula, interception submodel, spatially distributed evapotranspiration routine and alternative forrnulations of lake evapotranspiration. Sensitivity analyses were thereafter rnade to illustrate the effects of uncertainty in the hydrological model structure versus those of the uncertainty in the climate change predictions.

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  • 10.
    Lindström, Göran
    et al.
    SMHI, Research Department, Hydrology.
    Johansson, Barbro
    SMHI, Professional Services.
    Persson, Magnus
    SMHI.
    Gardelin, Marie
    SMHI, Professional Services.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Development and test of the distributed HBV-96 hydrological model1997In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 201, no 1-4, p. 272-288Article in journal (Refereed)
    Abstract [en]

    A comprehensive re-evaluation of the HBV hydrological model has been carried out. The objectives were to improve its potential for making use of spatially distributed data, to make it more physically sound and to improve the model performance. The new version, HBV-96, uses subbasin division with a typical resolution of 40 km(2), although any resolution can be used. In addition, each subbasin is divided into elevation bands, vegetation and snow classes. Automatic weighting of precipitation and temperature stations was introduced and a new automatic calibration scheme was developed. The modifications led to significant improvements in model performance. In seven test basins the average value of the efficiency criterion R-2 increased from 86 to 89%, with improvements in both the calibration and verification periods. (C) 1997 Elsevier Science B.V.

  • 11.
    Yang, Wei
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden2015In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 15, no 9, p. 2037-2057Article in journal (Refereed)
    Abstract [en]

    As the risk of a forest fire is largely influenced by weather, evaluating its tendency under a changing climate becomes important for management and decision making. Currently, biases in climate models make it difficult to realistically estimate the future climate and consequent impact on fire risk. A distribution-based scaling (DBS) approach was developed as a post-processing tool that intends to correct systematic biases in climate modelling outputs. In this study, we used two projections, one driven by historical reanalysis (ERA40) and one from a global climate model (ECHAM5) for future projection, both having been dynamically down-scaled by a regional climate model (RCA3). The effects of the post-processing tool on relative humidity and wind speed were studied in addition to the primary variables precipitation and temperature. Finally, the Canadian Fire Weather Index system was used to evaluate the influence of changing meteorological conditions on the moisture content in fuel layers and the fire-spread risk. The forest fire risk results using DBS are proven to better reflect risk using observations than that using raw climate outputs. For future periods, southern Sweden is likely to have a higher fire risk than today, whereas northern Sweden will have a lower risk of forest fire.

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1 - 11 of 11
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