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  • 1.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Modelling nutrient retention in the coastal zone of an eutrophic sea2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 20, p. 5753-5769Article in journal (Refereed)
  • 2.
    Edman, Anna
    et al.
    SMHI, Professional Services.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Hjerdt, Niclas
    SMHI, Core Services.
    Marmefelt, Eleonor
    SMHI, Professional Services.
    Lundholm, Karen
    SMHI.
    HOME Vatten i Bottenvikens vattendistrikt: Integrerat modellsystem för vattenkvalitetsberäkningar2008Report (Other academic)
    Abstract [sv]

    SMHI har utvecklat ett interaktivt modellsystem för vattenkvalitetberäkningar i mark, sjöar, vattendrag och kustvatten, HOME Vatten. I detta uppdrag har HOME Vatten implementerats i Bottenhavets vattendistrikt, dvs. i Västerbotten, Jämtland, Västernorrland, Dalarna, Gävleborg och Uppsala län. De ingående modellerna i HOME Vatten är HBV-NP (PLC5-uppsättningen) modellen för mark, sjöar och vattendrag samt Kustzonsmodellen för kustvattnen. Atmosfärsdepositionen både på land och i kustområdet beräknas av den atmosfärskemiska MATCH modellen.HOME Vatten har utvecklats för att vara ett verktyg i svensk vattenförvaltning med speciellt fokus på EUs ramdirektiv för vatten.Modelluppsättningarna i Västerbotten, Västernorrland och Gävleborg läns kustvatten har validerats mot tillgängliga mätdata, och visar en god överrensstämmelse med data.

  • 3.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Model assessment of the predicted environmental consequences for OSPAR problem areas following nutrient reductions2009Report (Other academic)
    Abstract [en]

    The Swedish Coastal and Ocean Biogeochemical model (SCOBI) is used for the assessment of eutrophication status in the Skagerrak and the Kattegat, and of the following long-term effects on the ecosystem for the 50% nutrient reduction target (PARCOM Recommendation 88/2). Model validation and the final reporting of the results in accordance with the OSPAR comprehensive procedure are presented.The model is validated by a comparison of a long time series (1985-2002) of the model results to data from a number of stations representing different parts of the model domain. A quantitative examination of the model performance is done by a comparison between the seasonal and annual averages of the model results and in-situ data. The model response to nutrient reductions shows that reducing nutrient inputs from land have the largest effects on the nitrate concentrations in the Kattegat and along the Swedish coast in the Skagerrak. The effects on phosphate concentrations are relatively small. The largest effect obtained from a 50% reduction of anthropogenic nitrogen and phosphorus from the runoff in one country alone is obtained for Sweden. This model experiment reduces the nitrate and chlorophyll concentrations in the Swedish coastal waters by 5%-10% and 3%-6%, respectively. The annual net production is reduced by 2%-4% and changes in sedimentation are less than 1%. The largest reduction is found in the Kattegat.The combined effect from a 50% reduction of anthropogenic nutrient supplies from land and an anticipated realistic reduction of nutrient concentrations in the Baltic Sea and the North Sea reduces the nitrate and phosphate concentrations in the Kattegat and the Swedish parts of the Skagerrak coastal area by 20%-30%. The average chlorophyll concentrations are reduced by 8%-11%. The annual net production and the sedimentation are reduced by 12%-20% and 5%-12%, respectively.

  • 4.
    Hjerdt, Niclas
    et al.
    SMHI, Core Services.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Marmefelt, Eleonor
    SMHI, Professional Services.
    Lundholm, Karen
    SMHI.
    HOME Vatten i Bottenhavets vattendistrikt: Integrerat modellsystem för vattenkvalitetsberäkningar2008Report (Other academic)
    Abstract [sv]

    SMHI har utvecklat ett interaktivt modellsystem för vattenkvalitetberäkningar i mark, sjöar, vattendrag och kustvatten, HOME Vatten. I detta uppdrag har HOME Vatten implementerats i Bottenhavets vattendistrikt, dvs. i Västerbotten, Jämtland, Västernorrland, Dalarna, Gävleborg och Uppsala län. De ingående modellerna i HOME Vatten är HBV-NP (PLC5-uppsättningen) modellen för mark, sjöar och vattendrag samt Kustzonsmodellen för kustvattnen. Atmosfärsdepositionen både på land och i kustområdet beräknas av den atmosfärskemiska MATCH-modellen. HOME Vatten har utvecklats för att vara ett verktyg i svensk vattenförvaltning med speciellt fokus på EUs ramdirektiv för vatten. Modelluppsättningarna i Västerbotten, Västernorrland och Gävleborg läns kustvatten har validerats mot tillgängliga mätdata, och visar en god överrensstämmelse med data. Key words/sök-, nyckelord HOME Vatten, HBV-NP, PLC5, Kustzonsmodell, integrerat modellsystem, biogeokemisk modell Supplementary notes/Tillägg Number of pages/Antal sidor 48 Language/Språk Svenska ISSN and

  • 5. Humborg, C
    et al.
    Smedberg, E
    Blomqvist, S
    Morth, C M
    Brink, J
    Rahm, Lars
    SMHI, Research Department, Oceanography.
    Danielsson, A
    Sahlberg, Jörgen
    SMHI, Professional Services. SMHI, Research Department, Oceanography.
    Nutrient variations in boreal and subarctic Swedish rivers: Landscape control of land-sea fluxes2004In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 49, no 5, p. 1871-1883Article in journal (Refereed)
    Abstract [en]

    We examined the hypothesis that the extent of vegetation cover governs the fluxes of nutrients from boreal and subarctic river catchments to the sea. Fluxes of total organic carbon (TOC) and dissolved inorganic nitrogen, phosphorus, and dissolved silicate (DIN, DIP, and DSi, respectively) are described from 19 river catchments and subcatchments (ranging in size from 34 to 40,000 km(2)) in northern Sweden with a detailed analysis of the rivers Lulealven and Kalixalven. Fluxes of TOC, DIP, and DSi increase by an order of magnitude with increasing proportion of forest and wetland area, whereas DIN did not follow this pattern but remained constantly low. Principal component analysis on landscape variables showed the importance of almost all land cover and soil type variables associated with vegetation, periglacial environment, soil and bedrock with slow weathering rates, boundary of upper tree line, and percentage of lake area. A cluster analysis of the principal components showed that the river systems could be separated into mountainous headwaters and forest and wetland catchments. This clustering was also valid in relation to river chemistry (TOC, DIP, and DSi) and was confirmed with a redundancy analysis, including river chemistry and principal components as environmental variables. The first axis explains 89% of the variance in river chemistry and almost 100% of the variance in the relation between river chemistry and landscape variables. These results suggest that vegetation change during interglacial periods is likely to have had a major effect on inputs of TOC, DIP, and DSi into the past ocean.

  • 6.
    Häggström, Martin
    et al.
    SMHI, Core Services.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Analys av snösmältningsförlopp1993Report (Other academic)
  • 7.
    Marmefelt, Eleonor
    et al.
    SMHI, Professional Services.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Bergstrand, Marie
    SMHI, Core Services.
    HOME Vatten i södra Östersjöns vattendistrikt: Integrerat modellsystem för vattenkvalitetsberäkningar2007Report (Other academic)
    Abstract [sv]

    SMHI har utvecklat ett interaktivt modellsystem för vattenkvalitetberäkningar i mark, sjöar, vattendrag och kustvatten, HOME Vatten. Ett av de första områden som systemet implementerades i var Östergötlands skärgård, med tillhörande avrinningsområde. I detta uppdrag har HOME Vatten implementerats i resterande områden i södra Östersjöns vattendistrikt, dvs. i Kalmar, Blekinge, Skåne och Gotlands län. De ingående modellerna i HOME Vatten är HBV-N (TRK) modellen för mark, sjöar och vattendrag samt Kustzonsmodellen för kustvattnen. Atmosfärsdepositionen både på land och i kustområdet beräknas av den atmosfärskemiska MATCH-modellen.HOME Vatten har utvecklats för att vara ett verktyg i svensk vattenförvaltning med speciellt fokus på EUs ramdirektiv för vatten. Modelluppsättningarna i Kalmar och Skåne-Blekinge läns kustvatten har validerats mot tillgängliga mätdata, och visar en god överrensstämmelse med data.I Gotlands län förekommer inget kustvattenkontrollprogram, varför modellen inte har kunnat valideras i detta område.

  • 8.
    Omstedt, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Some results from a joint Swedish-Finnish sea ice experiment, March, 19771978Report (Other academic)
    Abstract [en]

    A joint Swedish-Finnish sea-ice experiment was performed during March 1977. Measurements in the atmosphere, ice and sea were made during six days onboard the Finnish Research vessel Aranda stationed in the ice field in the Bay of Bothnia. During two days measurements were also carried out from thetwo Swedish icebreakers Atle and Tor. This report presents the data and some results from the Swedish group.

  • 9.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    MODELING THE THERMAL REGIME OF A LAKE DURING THE WINTER SEASON1988In: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 15, no 2, p. 151-159Article in journal (Refereed)
  • 10.
    Sahlberg, Jörgen
    SMHI, Professional Services. SMHI, Research Department, Oceanography.
    Physical modelling of the Akkajaure reservoir2003In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 7, no 3, p. 268-282Article in journal (Refereed)
    Abstract [en]

    This paper describes the seasonal temperature development in the Akkajaure reservoir. one of the largest Swedish reservoirs. It lies in the headwaters of the river Lulealven in northern Sweden: it is 60 km long and 5 km wide with a maximum depth of 92 m. The maximum allowed variation in surface water level is 30 m. The temperature field in the reservoir is important for many biochemical processes. A one-dimensional lake model of the Akkajaure reservoir is developed from a lake model by Sahlberg (1983 and 1988). The dynamic eddy viscosity is calculated by a two equation turbulence model, a k-epsilon model and the hypolimnic eddy diffusivity formulation which is a function of the stability frequency (Hondzo et al., 1993). A comparison between calculated and measured temperature profiles showed a maximum discrepancy of 0.5-1.0degreesC over the period 1999-2002. Except for a few days in summer, the water temperature is vertically homogeneous. Over that period of years, a weak stratification of temperature occurred on only one to two weeks a year on different dates in July and August. This will have biological consequences.

  • 11.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Randdata från öppet hav till kustzonsmodellerna: Exemplet södra Östergötland2005Report (Other academic)
  • 12.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    The Coastal Zone Model2009Report (Other academic)
    Abstract [en]

    SMHI has developed a model system for water quality calculations on land, in lakes and rivers and in coastal zone waters around Sweden. The system is called HOME Water where HOME stands for Hydrology, Oceanography and Meteorology for the Environment. The focus in this report is to describe the coastal zone model which is the part of the HOME Water system that calculates the state in the coastal zone along the whole Swedish coast. The coastal zone model is a coupled 1-dimensional physical and biogeochemical model. The physical model is called the Probe model and is fully described by Svensson (1998). It calculates the horizontal velocities, temperature and salinity profiles. The surface mixing is calculated by a k -e turbulence model and the bottom mixing is a parameterization based on the stability in the bottom water. Ice formation growth and decay is also included in the model. Probe has a high vertical resolution with a vertical grid cell size of 0.5m in the top 4m. The grid cell size then increases as the depth increases. In the depth interval 4 -70m the cell size is 1.0m, from 70 – 100m it is 2m, from 100-250m it is 5m and if the depth is larger then 250m the grid cell size is 10m. This means that the model calculates the vertical profiles of all its variables and assumes that they are horizontally homogeneous in the studied area. In order to include horizontal variations in a larger area it is divided into several sub-basins. These subbasins are identical to the defined national water bodies according to the Water Framework Directive (WFD). Each sub-basin is described by the hypsographical curve. Connecting sub-basins exchange water and properties through connecting sounds. The biogeochemical model is called SCOBI (Swedish Coastal Ocean BIogeochemical model). In SCOBI nine variables are solved where seven are the pelagic variables: zooplankton, phytoplankton, detritus, nitrate, ammonium, phosphate and oxygen. In the bentic layer the model solves for the two variables nitrogen and phosphorus.

  • 13.
    Sahlberg, Jörgen
    et al.
    SMHI, Professional Services.
    Gustavsson, Hanna
    SMHI.
    HOME Vatten i Mälaren2010Report (Other academic)
    Abstract [en]

    The HOME Water system has been applied to lake Mälaren. HOME Water is an integrated model system for water quality calculations on land, in rivers and lakes and the coastal waters around Sweden. The model system consists of the hydrological HYPE model and the coastal zone model (Probe-SCOBI model). The model system is used for long time calculations normally 15-20 years. The hydrological HYPE model is developed for water and water quality transport calculations with high spatial resolution. The water quality is here defined as nitrogen, phosphorus and dissolved organic carbon. In the HYPE application to the whole of Sweden (S-HYPE) consists of 17313 different catchments. The total number of subcatchments around lake Mälaren is 973 in this study. Despite this large number of catchments the area close to lake Mälaren is not included in this HYPE version. The coastal zone model is a one dimensional model with high vertical resolution. To resolve the horizontal variations in lake Mälaren the lake has been divided into 39 different water bodies. These water bodies exchange properties through connecting sounds. The HOME Water system calculates the physical and biogeochemical conditions on a daily basis during the calculations period 1990-2008. Measurements from different parts of lake Mälaren are used in the verification study. The data from 20 measuring stations are extracted from the SLU’s homepage for the main part of lake Mälaren except in the eastern part where data is extracted from the Stockholm Water measuring program. The verification result shows that the coastal zone model calculations of the water temperature, nitrogen and oxygen are in good agreement with the measurements. But for phosphorus and chlorophyll the agreement with measurements is not so good. The result from the phosphorus calculations show that soluble phosphorus agrees rather well with measurements except during the winter time when the calculated concentration is to large. The problem is the calculated total phosphorus is too small compared to the measurements especially in the western part of lake Mälaren. In the eastern part the results show that the calculated mean concentration is in good agreement with the measurements but the variations in the calculated total phosphorus are to large. A general conclusion for the whole lake Mälaren is that the soluble part of the total phosphorus is too large and the particulate part to small. Thus the HYPE model overestimates the transport of the soluble phosphorus and underestimates the transport of the particulate phosphorus. This study also shows that the calculated soluble phosphorus in the bottom water is too large when the oxygen conditions are decreasing. The process that describes the size of the phosphorus exchange between water and sediment, depending on the oxygen concentration, becomes too large at too high oxygen concentrations. This process description will be corrected in the next version of the coastal zone model. The calculated chlorophyll concentration is underestimated in the whole lake. Probably this has to do with the fact that the model only has one type of plankton. In the next version of the coastal zone model there will be three different types of plankton which will simulate diatoms, flagellates and others and cyanobacteria.

  • 14.
    Sahlberg, Jörgen
    et al.
    SMHI, Professional Services.
    Marmefelt, Eleonor
    SMHI, Professional Services.
    Brandt, Maja
    SMHI, Core Services.
    Hjerdt, Niclas
    SMHI, Core Services.
    Lundholm, Karen
    SMHI.
    HOME Vatten i Norra Östersjöns vattendistrikt: Integrerat modellsystem för vattenkvalitetsberäkningar2008Report (Other academic)
    Abstract [sv]

    SMHI har utvecklat ett interaktivt modellsystem för vattenkvalitetberäkningar i mark, sjöar, vattendrag och kustvatten, HOME Vatten. I detta uppdrag har HOME Vatten implementerats i Norra Östersjöns vattendistrikt. De ingående modellerna i HOME Vatten är HBV NP (PLC5- uppsättningen) modellen för mark, sjöar och vattendrag samt Kustzonsmodellen för kustvattnen. Atmosfärsdepositionen både på land och i kustområdet har beräknats av den atmosfärskemiska MATCH-modellen.HOME Vatten har utvecklats för att vara ett verktyg i svensk vattenförvaltning med speciellt fokus på EUs ramdirektiv för vatten.Modelluppsättningarna har validerats mot tillgängliga mätdata, och visar en god överrensstämmelse med data.

  • 15.
    Sahlberg, Jörgen
    et al.
    SMHI, Professional Services.
    Olsson, Håkan
    SMHI, Core Services.
    Kustzonsmodell för norra Östergötlands skärgård2001Report (Other academic)
  • 16.
    Sahlberg, Jörgen
    et al.
    SMHI, Professional Services. SMHI, Research Department, Oceanography.
    Rahm, Lars
    SMHI, Research Department, Oceanography.
    Light limitation of primary production in high latitude reservoirs2005In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 9, no 6, p. 707-720Article in journal (Refereed)
    Abstract [en]

    To explore the effects of vertical mixing on the primary production in a northern reservoir, a Lagrangian particle dispersion model was coupled to a 1-D reservoir model where the vertical mixing was calculated using a k-epsilon model together with an empirically-based deep-water eddy viscosity. The primary production of each phytoplankton cell is assumed to be a function of the ambient light and not to be nutrient limited. The photoadaption follows first-order kinetics where the photoadaptive variables, alpha, beta, and P(m), describe the coefficients of the photosynthesis-irradiance curve. The model is applied to the northern reservoir Akkajaure, which is strongly regulated with a mean and maximum depth of 30 m and 100 m respectively. Based on the release of 1000 particles (plankton), the model calculated the mean primary production of each plankton, during four different growing seasons. Vertical mixing has a substantial effect on the vertical distribution of phytoplankton and, thus, on the primary production in a reservoir. It was found that primary production was greater in a cold summer with weak stratification than in a warm summer when the reservoir was more stratified.

  • 17.
    Sahlberg, Jörgen
    et al.
    SMHI, Professional Services.
    Törnevik, Håkan
    SMHI.
    A study of large scale cooling in the Bay of Bothnia1980Report (Other academic)
  • 18.
    Svensson, Urban
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    FORMULAS FOR PRESSURE-GRADIENTS IN ONE-DIMENSIONAL LAKE MODELS1989In: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, Vol. 94, no C4, p. 4939-4946Article in journal (Refereed)
1 - 18 of 18
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  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
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