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  • 301. Bengtsson, L.
    et al.
    Grahn, L
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Hydrological function of a thin extensive green roof in southern Sweden2005In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 36, no 3, p. 259-268Article in journal (Refereed)
    Abstract [en]

    The runoff from and the water balance of a thin extensive green roof with sedum-moss have been studied. The soil cover is about 3 cm underlain by a thin drainage layer. The water balance is determined on a monthly basis. The runoff from the green roof is much reduced compared to runoff from hard roofs because of evapotranspiration. The annual runoff is rather close to that of natural river basins. Although most rainy days there is no or little runoff from the roof, the highest observed daily runoff values are close to the daily rainfall. Runoff is initiated when the soil is at field capacity, which for the studied roof corresponds to 9 mm storage. After that, on a not very short time basis, the runoff equals the precipitation. The reduction of the daily runoff can be described in a simple way knowing the daily precipitation, potential evaporation and storage capacity of the green roof.

  • 302. Bennartz, R
    et al.
    Michelson, Daniel
    SMHI, Core Services.
    Correlation of precipitation estimates from spaceborne passive microwave sensors and weather radar imagery for BALTEX PIDCAP2003In: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 24, no 4, p. 723-739Article in journal (Refereed)
    Abstract [en]

    This paper describes the evaluation of a-combined radar and passive microwave dataset obtained during the PIDCAP study of the Baltic Sea Experiment (BALTEX), where three-dimensional volumes of data from the Gotland radar were obtained timed according to the overpasses of the DMSP-satellites F10 and F13. Both satellites are 'equipped with a Special Sensor Microwave/Imager (SSM/I), suitable for precipitation retrievals. We compare radar precipitation estimates, convolved to the native resolution of the SSM/I, at different altitudes with polarization and scattering indices (S-85) derived from the SSM/I. For all 22 overpasses investigated here radar precipitation estimates at 3-4 km altitude correlate well with the SSM/I-derived S-85 (average correlation coefficient = 0.70). Although more directly linked to surface precipitation, polarization indices have been found to be less correlated with radar data, due to limitations inherent in the remote sensing of precipitation at higher latitudes. A stratification of the dataset into frontal and convective events revealed significant variations in these relationships for different types of precipitation events, thus reflecting different cloud microphysical processes associated with precipitation initialization. The relationship between S85 and radar rain estimates at higher altitudes varies considerably for different convective and frontal events. The sensitivity of S-85 to radar-derived rain rate ranges from 3.1 K mm(-1) h(-1) for a strong convective event to about 25 K mm(-1) h(-1) for the frontal and about 70 mm(-1) h(-1) for the small-scale convective events. For extrapolated surface precipitation estimates, sensitivities decrease to 14 mm(-1) h(-1) and 25 mm(-1) h(-1) for frontal and small-scale convective precipitation, respectively.

  • 303. Benner, S G
    et al.
    Blowes, D W
    Gould, W D
    Herbert, Roger B
    Ptacek, C J
    Geochemistry of a permeable reactive barrier for metals and acid mine drainage1999In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 33, no 16, p. 2793-2799Article in journal (Refereed)
    Abstract [en]

    A permeable reactive barrier, designed to remove metals and generate alkalinity by promoting sulfate reduction and metal sulfide precipitation, was installed in August 1995 into an aquifer containing effluent from mine tailings. Passage of groundwater through the barrier results in striking improvement in water quality. Dramatic changes in concentrations of SO4 (decrease of 2000−3000 mg/L), Fe (decrease of 270−1300 mg/L), trace metals (e.g., Ni decreases 30 mg/L), and alkalinity (increase of 800−2700 mg/L) are observed. Populations of sulfate reducing bacteria are 10 000 times greater, and bacterial activity, as measured by dehydrogenase activity, is 10 times higher within the barrier compared to the up-gradient aquifer. Dissolved sulfide concentrations increase by 0.2−120 mg/L, and the isotope 34S is enriched relative to 32S in the dissolved phase SO42- within the barrier. Water chemistry, coupled with geochemical speciation modeling, indicates the pore water in the barrier becomes supersaturated with respect to amorphous Fe sulfide. Solid phase analysis of the reactive mixture indicates the accumulation of Fe monosulfide precipitates. Shifts in the saturation states of carbonate, sulfate, and sulfide minerals and most of the observed changes in water chemistry in the barrier and down-gradient aquifer can be attributed, either directly or indirectly, to bacterially mediated sulfate reduction.

  • 304.
    Bennich, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Bredberg, William
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Olsson, Jimmy
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Rulewski Stenberg, Louis
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Smith, Malin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Söderqvist, Johnny
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    En jämförelse mellan fjärranalystekniker och vågbojar för mätning av oceanografiska parametrar i svenska vatten2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    För övervakning av svenska vatten krävs noggranna mätningar av oceanografiska parametrar såsom våghöjd, vågriktning, ytvattentemperatur och ytströmmar. Mätdata för parametrarna samlas in av Sveriges Meteorologiska och Hydrologiska Institut (SMHI) och används till prognoser, sjöfart samt forskning. I denna studie undersöktes möjligheten att ersätta eller komplettera vågbojarna av modellen Directional Waverider MkIII som SMHI använder idag, med ny kommersiellt tillgänglig fjärranalysteknik. Projektet begränsades till att studera två högfrekvens-radartekniker och en X-bandradar. Studien är platsspecifik och utreder kvalitetsmässiga, ekonomiska och miljömässiga för- och nackdelar med de utvalda radarteknikerna i relation till vågbojarna. En litteraturstudie och modellering av data över parametrar som påverkar radarteknikernas räckvidd och datatillgänglighet genomfördes. Ur modelleringen drogs slutsatsen att det är möjligt att erhålla likvärdig datatillgänglighet med vågradar som med vågboj. Vidare modellering ledde till slutsatsen att radarteknikerna begränsas till ungefär hälften av sin optimala räckvidd i Östersjön på grund av den låga salthalten, och därför är Sveriges västkust bättre lämpad för placering av radarteknik. Undersökning av isbildning i havsvatten, som kan begränsa radarteknikernas räckvidd, ledde till slutsatsen att Sveriges västkust också är att föredra utifrån detta perspektiv. Med anledning av radarteknikers möjlighet att utföra mätningar över större områden, finner studien att det finns goda grunder för att motivera en ersättning eller komplettering av vågbojarna med modern radarteknik. Vidare talar radarteknikernas goda anpassningsförmåga, lägre inverkan på miljön och enklare underhållskrav jämfört med vågbojarna till dess fördel. Att övergå till radarteknik medför däremot högre installations- och driftkostnader i jämförelse med vågbojar.

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  • 305.
    Benskin, Jonathan
    et al.
    University of Alberta, Canada.
    Ahrens, Lutz
    Institute for Coastal Research, Geesthacht, Tyskland.
    Muir, Derek
    Environment Canada, Kanada.
    Scott, Brian
    Environment Canada, Kanada.
    Spencer, Christine
    Environment Canada, Kanada.
    Rosenberg, Bruno
    Department of Fisheries and Oceans, Canada.
    Tomy, Gregg
    Department of Fisheries and Oceans, Canada.
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Lohmann, Rainer
    University of Rhode Island, USA.
    Martin, Jonathan
    University of Alberta, Canada.
    Manufacturing Origin of Perfluorooctanoate (PFOA) in Atlantic and Canadian Arctic Seawater2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 2, p. 677-685Article in journal (Refereed)
    Abstract [en]

    The extent to which different manufacturing sources and long-range transport pathways contribute to perfluorooctanoate (PFOA) in the world’s oceans, particularly in remote locations, is widely debated. Here, the relative contribution of historic (i.e., electrochemically fluorinated) and contemporary (i.e., telomer) manufacturing sources was assessed for PFOA in various seawater samples by an established isomer profiling technique. The ratios of individual branched PFOA isomers were indistinguishable from those in authentic historic standards in 93% of the samples examined, indicating that marine processes had little influence on isomer profiles, and that isomer profiling is a valid source apportionment tool for seawater. Eastern Atlantic PFOA was largely (83−98%) of historic origin, but this decreased to only 33% close to the Eastern U.S. seaboard. Similarly, PFOA in the Norwegian Sea was near exclusively historic, but the relative contribution decreased to ∼50% near the Baltic Sea. Such observations of contemporary PFOA in coastal source regions coincided with elevated concentrations, suggesting that the continued production and use of PFOA is currently adding to the marine burden of this contaminant. In the Arctic, a spatial trend was observed whereby PFOA in seawater originating from the Atlantic was predominantly historic (up to 99%), whereas water in the Archipelago (i.e., from the Pacific) was predominantly of contemporary origin (as little as 17% historic). These data help to explain reported temporal and spatial trends from Arctic wildlife biomonitoring, and suggest that the dominant PFOA source(s) to the Pacific and Canadian Arctic Archipelago are either (a) from direct emissions of contemporary PFOA via manufacturing or use in Asia, or (b) from atmospheric transport and oxidation of contemporary PFOA-precursors.

  • 306.
    Benskin, Jonathan P.
    et al.
    University of Alberta, Canada .
    Muir, Derek C. G.
    Environm Canada, Canada .
    Scott, Brian F.
    Environm Canada, Canada .
    Spencer, Christine
    Environm Canada, Canada .
    De Silva, Amila O.
    Environm Canada, Canada .
    Kylin, Henrik
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Martin, Jonathan W.
    University of Alberta, Canada .
    Morris, Adam
    University of Guelph, Canada .
    Lohmann, Rainer
    University of Rhode Isl, RI 02882 USA .
    Tomy, Gregg
    Department Fisheries and Oceans Canada, Canada .
    Rosenberg, Bruno
    Department Fisheries and Oceans Canada, Canada .
    Taniyasu, Sachi
    National Institute Adv Ind Science and Technology, Japan .
    Yamashita, Nobuyoshi
    National Institute Adv Ind Science and Technology, Japan .
    Perfluoroalkyl Acids in the Atlantic and Canadian Arctic Oceans2012In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 46, no 11, p. 5815-5823Article in journal (Refereed)
    Abstract [en]

    We report here on the spatial distribution of C-4, C-6, and C-8 perfluoroalkyl sulfonates, C-6-C-14 perfluoroalkyl carboxylates, and perfluorooctanesulfonamide in the Atlantic and Arctic Oceans, including previously unstudied coastal waters of North and South America, and the Canadian Arctic Archipelago. Perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS) were typically the dominant perfluoroalkyl acids (PFAAs) in Atlantic water. In the midnorthwest Atlantic/Gulf Stream, sum PFAA concentrations (Sigma PFAAs) were low (77-190 pg/L) but increased rapidly upon crossing into U.S. coastal water (up to 5800 pg/L near Rhode Island). Sigma PFAAs in the northeast Atlantic were highest north of the Canary Islands (280-980 pg/L) and decreased with latitude. In the South Atlantic, concentrations increased near Rio de la Plata (Argentina/Uruguay; 350-540 pg/L Sigma PFAAs), possibly attributable to insecticides containing N-ethyl perfluorooctanesulfonamide, or proximity to Montevideo and Buenos Aires. In all other southern hemisphere locations, Sigma PFAAs were less than210 pg/L. PFOA/PFOS ratios were typically greater than= 1 in the northern hemisphere, similar to 1 near the equator, and less than= 1 in the southern hemisphere. In the Canadian Arctic, Sigma PFAAs ranged from 40 to 250 pg/L, with perfluoroheptanoate, PFOA, and PFOS among the PFAAs detected at the highest concentrations. PFOA/PFOS ratios (typically greater thangreater than1) decreased from Baffin Bay to the Amundsen Gulf; possibly attributable to increased atmospheric inputs. These data help validate global emissions models and contribute to understanding of long-range transport pathways and sources of PFAAs to remote regions.

  • 307. Berdalet, Elisa
    et al.
    Anderson, Clarissa
    Banas, Neil
    Davis, Timothy
    Clarke, David
    Jeong, Hae Jin
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Kudela, Raphael M.
    Lapointe, Brian
    Lim, Po Teen
    Martinelli Filho, Jose Eduardo
    Serrao, Ester
    Siano, Raffaele
    Silke, Joe
    Trainer, Vera
    van Tussenbroek, Brigitta
    Wood, Susie
    Yniguez, Aletta
    Miloslavich, Patricia
    Enevoldsen, Henrik
    GLOBALHAB (IOC-UNESCO AND SCOR): LATINAMERICA CONTRIBUTION TO THE INTERNATIONAL COORDINATION FOR SOUND KNOWLEDGE OF HABS AND MANAGEMENT OF THEIR IMPACTS2021In: Phycologia, ISSN 0031-8884, E-ISSN 2330-2968, Vol. 60, p. 86-87Article in journal (Refereed)
  • 308. Berdalet, Elisa
    et al.
    Kudela, Raphael
    Urban, Ed
    Enevoldsen, Henrik
    Banas, Neil S.
    Bresnan, Eileen
    Burford, Michele
    Davidson, Keith
    Gobler, Christopher J.
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Lim, Po Teen
    Mackenzie, Lincoln
    Montresor, Marina
    Trainer, Vera L.
    Usup, Gires
    Yin, Kedong
    GlobalHAB A New Program to Promote International Research, Observations, and Modeling of Harmful Algal Blooms in Aquatic Systems2017In: Oceanography, ISSN 1042-8275, Vol. 30, no 1, p. 70-81Article in journal (Refereed)
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  • 309. Berdalet, Elisa
    et al.
    Pavaux, Anne-Sophie
    Abos-Herrandiz, Rafael
    Travers, Muriel
    Appere, Gildas
    Vila, Magda
    Thomas, Jeremy
    de Haro, Luc
    Estrada, Marta
    Inmaculada Medina-Perez, Noemi
    Viure, Laia
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Lemee, Rodolphe
    Environmental, human health and socioeconomic impacts of Ostreopsis spp. Blooms in the NW Mediterranean2022In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 119, article id 102320Article in journal (Refereed)
  • 310.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Almen, Fredrik
    SMHI, Core Services.
    Bozhinova, Denica
    SMHI, Research Department, Hydrology.
    HydroGFD3.0 (Hydrological Global Forcing Data): a 25 km global precipitation and temperature data set updated in near-real time2021In: Earth System Science Data, ISSN 1866-3508, E-ISSN 1866-3516, Vol. 13, no 4, p. 1531-1545Article in journal (Refereed)
    Abstract [en]

    HydroGFD3 (Hydrological Global Forcing Data) is a data set of bias-adjusted reanalysis data for daily precipitation and minimum, mean, and maximum temperature. It is mainly intended for large-scale hydrological modelling but is also suitable for other impact modelling. The data set has an almost global land area coverage, excluding the Antarctic continent and small islands, at a horizontal resolution of 0.25 degrees, i.e. about 25 km. It is available for the complete ERA5 reanalysis time period, currently 1979 until 5 d ago. This period will be extended back to 1950 once the back catalogue of ERA5 is available. The historical period is adjusted using global gridded observational data sets, and to acquire real-time data, a collection of several reference data sets is used. Consistency in time is attempted by relying on a background climatology and only making use of anomalies from the different data sets. Precipitation is adjusted for mean bias as well as the number of wet days in a month. The latter is relying on a calibrated statistical method with input only of the monthly precipitation anomaly such that no additional input data about the number of wet days are necessary. The daily mean temperature is adjusted toward the monthly mean of the observations and applied to 1 h time steps of the ERA5 reanalysis. Daily mean, minimum, and maximum temperature are then calculated. The performance of the HydroGFD3 data set is on par with other similar products, although there are significant differences in different parts of the globe, especially where observations are uncertain. Further, HydroGFD3 tends to have higher precipitation extremes, partly due to its higher spatial resolution. In this paper, we present the methodology, evaluation results, and how to access the data set at https://doi.org/10.5281/zenodo.3871707 (Berg et al., 2020).

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    HydroGFD3.0 (Hydrological Global Forcing Data): a 25 km global precipitation and temperature data set updated in near-real time
  • 311.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Model Consistent Pseudo-Observations of Precipitation and Their Use for Bias Correcting Regional Climate Models2015In: Climate, E-ISSN 2225-1154, Vol. 3, no 1, p. 118-132Article in journal (Refereed)
    Abstract [en]

    Lack of suitable observational data makes bias correction of high space and time resolution regional climate models (RCM) problematic. We present a method to construct pseudo-observational precipitation data by merging a large scale constrained RCM reanalysis downscaling simulation with coarse time and space resolution observations. The large scale constraint synchronizes the inner domain solution to the driving reanalysis model, such that the simulated weather is similar to observations on a monthly time scale. Monthly biases for each single month are corrected to the corresponding month of the observational data, and applied to the finer temporal resolution of the RCM. A low-pass filter is applied to the correction factors to retain the small spatial scale information of the RCM. The method is applied to a 12.5 km RCM simulation and proven successful in producing a reliable pseudo-observational data set. Furthermore, the constructed data set is applied as reference in a quantile mapping bias correction, and is proven skillful in retaining small scale information of the RCM, while still correcting the large scale spatial bias. The proposed method allows bias correction of high resolution model simulations without changing the fine scale spatial features, i.e., retaining the very information required by many impact models.

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  • 312.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Christensen, Ole B.
    Klehmet, Katharina
    SMHI, Research Department, Hydrology.
    Lenderink, Geert
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Teichmann, Claas
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Summertime precipitation extremes in a EURO-CORDEX 0.11 degrees ensemble at an hourly resolution2019In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 19, no 4, p. 957-971Article in journal (Refereed)
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  • 313.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Near-real-time adjusted reanalysis forcing data for hydrology2018In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 22, no 2, p. 989-1000Article in journal (Refereed)
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  • 314.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Norin, Lars
    SMHI, Research Department, Atmospheric remote sensing.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Creation of a high resolution precipitation data set by merging gridded gauge data and radar observations for Sweden2016In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 541, p. 6-13Article in journal (Refereed)
  • 315.
    Berga, Mercè
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Biological Oceanography, Leibniz Institute for Baltic Sea Research Warnemünde, Germany.
    Zha, Yinghua
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Székely, Anna J.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Langenheder, Silke
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Functional and Compositional Stability of Bacterial Metacommunities in Response to Salinity Changes2017In: Frontiers in Microbiology, E-ISSN 1664-302X, Vol. 8, article id 948Article in journal (Refereed)
    Abstract [en]

    Disturbances and environmental change are important factors determining the diversity,composition, and functioning of communities. However, knowledge about how naturalbacterial communities are affected by such perturbations is still sparse. We performeda whole ecosystem manipulation experiment with freshwater rock pools where weapplied salinity disturbances of different intensities. The aim was to test how thecompositional and functional resistance and resilience of bacterial communities,alpha- and beta-diversity and the relative importance of stochastic and deterministiccommunity assembly processes changed along a disturbance intensity gradient.We found that bacterial communities were functionally resistant to all salinity levels (3, 6, and 12 psu) and compositionally resistant to a salinity increase to 3 psu andresilient to increases of 6 and 12 psu. Increasing salinities had no effect on local richnessand evenness, beta-diversity and the proportion of deterministically vs. stochasticallyassembled communities. Our results show a high functional and compositional stabilityof bacterial communities to salinity changes of different intensities both at localand regional scales, which possibly reflects long-term adaptation to environmentalconditions in the study system.

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  • 316. Berggren, M.
    et al.
    Bengtson, P.
    Soares, A. R. A.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Climate Impacts Research Centre (CIRC).
    Terrestrial support of zooplankton biomass in northern rivers2018In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 63, no 6, p. 2479-2492Article in journal (Refereed)
    Abstract [en]

    The contribution of terrestrially derived carbon to micro-crustacean zooplankton biomass (i.e., allochthony) has been previously studied in lakes, reservoirs, and estuaries, but little is known about zooplankton allochthony in rivers. In lacustrine environments, allochthony is regulated by distinct selective feeding behavior of different taxa. However, we hypothesized that restricted possibility for selective grazing in turbulent environments such as rivers would decouple zooplankton from specific microbial and algal food resources, such that their allochthony would mirror the terrestrial contribution to the surrounding bulk particle pool. We tested this idea by analyzing allochthony in 13 widely distributed Swedish rivers, using a dual-isotope mixing model. Zooplankton biomasses were generally low, and allochthony in different micro-crustacean groups (Cladocera, Cyclopoida, Calanoida) varied from 2% to 77%. As predicted, there were no correlations between allochthony and variables indicating the supply of algal and microbial food resources, such as chlorophyll a and bacterial production. Instead, the allochthony was generally similar to the share allochthonous contribution in bulk particulate organic matter, with relationships close to the 1 : 1 line. The zooplankton community allochthony was strongly regulated by the ecosystem metabolic balance between production and respiration, which in turn was dependent upon the ratio between total autochthonous organic carbon concentrations and water color. Our study for the first time shows that micro-crustacean allochthony is regulated differently in rivers compared to in lacustrine systems, and points to inefficient support of zooplankton biomass by algal resources in turbulent waters.

  • 317. Berggren, Martin
    et al.
    Gudasz, Cristian
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Guillemette, Francois
    Hensgens, Geert
    Ye, Linlin
    Karlsson, Jan
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Systematic microbial production of optically active dissolved organic matter in subarctic lake water2020In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 65, no 5, p. 951-961Article in journal (Refereed)
    Abstract [en]

    The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.

  • 318. Berggren, Martin
    et al.
    Gudasz, Cristian
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Guillemette, Francois
    Hensgens, Geert
    Ye, Linlin
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Systematic microbial production of optically active dissolved organic matter in subarctic lake water2020In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 65, no 5Article in journal (Refereed)
    Abstract [en]

    The ecology and biogeochemistry of lakes in the subarctic region are particularly sensitive to changes in the abundance and optical properties of dissolved organic matter (DOM). External input of colored DOM to these lakes is an extensively researched topic, but little is known about potential reciprocal feedbacks between the optical properties of DOM and internal microbial processes in the water. We performed 28-day dark laboratory incubation trials on water from 101 subarctic tundra lakes in northern Sweden, measuring the microbial decay of DOM and the resulting dynamics in colored (CDOM) and fluorescent (FDOM) DOM components. While losses in dissolved oxygen during the incubations corresponded to a 20% decrease in mean DOM, conversely the mean CDOM and total FDOM increased by 22% and 30%, respectively. However, the patterns in microbial transformation of the DOM were not the same in all lakes. Notably, along the gradient of increasing ambient CDOM (water brownness), the lakes showed decreased microbial production of protein-like fluorescence, lowered DOM turnover rates and decreasing bacterial growth per unit of DOM. These trends indicate that browning of subarctic lakes systematically change the way that bacteria interact with the ambient DOM pool. Our study underscores that there is no unidirectional causal link between microbial processes and DOM optical properties, but rather reciprocal dependence between the two.

  • 319. Berggren, Martin
    et al.
    Sponseller, Ryan A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Soares, Ana R. Alves
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Toward an ecologically meaningful view of resource stoichiometry in DOM-dominated aquatic systems2015In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 37, no 3, p. 489-499Article in journal (Refereed)
    Abstract [en]

    Research on nutrient controls of planktonic productivity tends to focus on a few standard fractions of inorganic or total nitrogen (N) and phosphorus (P). However, there is a wide range in the degree to which land-derived dissolved organic nutrients can be assimilated by biota. Thus, in systems where such fractions form a majority of the macronutrient resource pool, including many boreal inland waters and estuaries, our understanding of bacterio-and phytoplankton production dynamics remains limited. To adequately predict aquatic productivity in a changing environment, improved standard methods are needed for determining the sizes of active (bioavailable) pools of N, P and organic carbon (C). A synthesis of current knowledge suggests that variation in the C:N:P stoichiometry of bioavailable resources is associated with diverse processes that differentially influence the individual elements across space and time. Due to a generally increasing organic nutrient bioavailability from C to N to P, we hypothesize that the C:N and N:P of bulk resources often vastly overestimates the corresponding ratios of bioavailable resources. It is further proposed that basal planktonic production is regulated by variation in the source, magnitude and timing of terrestrial runoff, through processes that have so far been poorly described.

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  • 320.
    Berghuijs, Wouter R.
    et al.
    Department of Civil Engineering, University of Bristol, Bristol, UK.
    Harrigan, Shaun
    Irish Climate Analysis and Research Units (ICARUS), Department of Geography, Maynooth University, Maynooth, Ireland.
    Kipnis, Evan L.
    Department of Ecosystem Science and Management, University of Wyoming, Laramie, Wyoming, USA.
    Dogulu, Nilay
    Department of Civil Engineering, Middle East Technical University, Ankara, Turkey.
    Floriancic, Marius
    Institute of Environmental Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland.
    Müller, Hannes
    Institute of Water Resources Management, Hydrology and Agricultural Hydraulic Engineering, Leibniz Universität Hannover, Hanover, Germany.
    Pohle, Ina
    Chair of Hydrology and Water Resources Management, Brandenburg University of Technology Cottbus-Senftenberg, Cottbus, Germany .
    Saia, Sheila M.
    Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York, USA.
    Sedlar, Frank
    Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, USA.
    Smoorenburg, Maarten
    Institute of Environmental Engineering, Swiss Federal Institute of Technology, Zurich, Switzerland.
    Teutschbein, Claudia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    van Emmerik, Tim
    Water resources section, Faculty of Civil Engineering and Geosciences, Delft University of Technology, The Netherlands.
    Creating Community for Early-Career Geoscientists: Student involvement in geoscience unions: A case study from hydrology2015In: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 96Article in journal (Refereed)
    Abstract [en]

    The American Geophysical Union (AGU) and the European Geosciences Union (EGU) play central roles in nurturing the next generation of geoscientists. Students and young scientists make up about one quarter of the unions’ active memberships [American Geophysical Union, 2013; European Geosciences Union, 2014], creating a major opportunity to include a new generation of geoscientists as more active contributors to the organizations’ activities, rather than merely as consumers.

    Both organizations are now explicitly expanding their bottom-up organizational structures to include early-career members (ECMs) by appointing student (AGU) and early-career scientist (EGU) representatives for their scientific divisions. (We refer to “early-career members” because AGU and EGU define student and postdoc members differently). Because this expansion is a recent development, it is still unclear what roles these representatives will play and how these roles will evolve over the coming years.

    We are ECMs in the hydrological sciences. Here we show how the Young Hydrological Society (YHS) used bottom-up initiatives, aligned closely with the newly appointed AGU and EGU representatives, to help improve the professional development of student and postdoc members by providing opportunities to increase their contributions to the geoscience unions. We call for a conversation on how ECMs can make the best use of these new opportunities to engage proactively with the unions.

  • 321.
    Berglund, Sara
    Stockholm University, Faculty of Science, Department of Meteorology .
    Tracing pathways in the ocean circulation: A temperature and salinity perspective2021Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The ocean circulation plays an essential role in our climate system. It redistributes heat, salt, carbon and other tracers across the globe, making the climate of Earth more moderate. This thesis targets density differences that are driving the ocean circulation. These differences are caused by changes in temperature and salinity. The analysis is based on the usage of Lagrangian trajectories simulated with velocity fields from an Earth System Model. The Lagrangian approach opens up for the possibility to follow specific water paths and water masses. The results herein provide a new insight to specific circulation patterns in the ocean, and which regions that play an important role in controlling temperature and salinity changes.

    In the first two articles, the Lagrangian divergence is introduced. It shows the geographical distribution of heat and salt changes of a simulated water mass. Using this, we are able to show that the northward flowing water in the Atlantic Ocean cools and freshens in the North Atlantic Subtropical Gyre, the Gulf Stream and the North Atlantic Current. Similarly, we show that the water flowing from the Drake Passage, following the Antarctic Circumpolar Current (ACC) and moving northwards into the Atlantic, Pacific and Indian oceans, transforms from cold and fresh to warm and saline. This warming and salinification are a result of, not only air-sea fluxes, but also interior mixing.

    In the third study, we show that 70% of the water flowing northwards as part of the Atlantic Meridional Overturning Circulation circuits the North Atlantic Subtropical Gyre at least once before it continues northwards. In the gyre, the water spirals downwards as it gets denser, due to a combination of air-sea fluxes and interior mixing. These results bring a new perspective on the Subtropical Gyre's role to the circulation patterns of the Atlantic Meridional Overturning Circulation.

    In the last part of this thesis, the circulation in the North Atlantic Ocean is traced into four different pathways. The pathways are visualised geographically together with their change in temperature, salinity and density. With this, we are able to show that the northward flowing water in the Atlantic Ocean exchanges heat and salt with the colder and fresher waters circulating the Subpolar Gyre.

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  • 322.
    Berglund, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Döös, Kristofer
    Stockholm University, Faculty of Science, Department of Meteorology .
    Groeskamp, Sjoerd
    McDougall, Trevor
    North Atlantic Ocean Circulation and Related Exchange of Heat and Salt Between Water Masses2023In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 50, no 13, article id e2022GL100989Article in journal (Refereed)
    Abstract [en]

    The meridional transport of mass, heat, and salt in the North Atlantic Ocean is often described for separate regions and parts, but rarely are all components of the circulation followed at once. Lagrangian trajectories have here been used to divide the North Atlantic Ocean circulation into four different pathways. In the boundary between the Subpolar and Subtropical Gyres, we show that the northward flowing waters exchange heat and salt with the water originating from the subpolar regions. This subsurface water mass exchange takes place in the first 1,000 m and is a key piece of the puzzle of how the Atlantic Meridional Overturning Circulation transports heat and salt. Between 30 & DEG; and 60 & DEG;N the northward flowing water loses 8.8 Gg/s salt to the Subpolar Gyre and an equivalent loss of only 1.7 Gg/s to the atmosphere due to the net fresh water influx.

  • 323.
    Berglund, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Döös, Kristofer
    Stockholm University, Faculty of Science, Department of Meteorology .
    Groeskamp, Sjoerd
    NIOZ Royal Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands.
    McDougall, Trevor J.
    School of Mathematics and Statistics, University of New South Wales, Australia.
    The contrasting roles of heat and salt in the overturning circulation of the North Atlantic OceanManuscript (preprint) (Other academic)
    Abstract [en]

    The meridional transport of mass, heat and salt in the North Atlantic Ocean is often described for separate regions and parts, but rarely are all components of the circulation followed in the same study. In the present study we use Lagrangian trajectories to divide the North Atlantic Ocean Circulation into four different pathways, all contributing to the total circulation and its appurtenant heat and salt changes. In the boundary between the Subpolar and Subtropical Gyres, we show that the northward flowing waters in the North Atlantic Ocean lose heat and salt through exchange with the water originating from the subpolar North Atlantic Ocean. This in turn means that the subpolar waters gain this amounts of heat and salt.Water leaving the subpolar region as North Atlantic Deep Water are clearly distinguishable from this subpolar water, both geographically and in temperature and salinity. The southward flowing North Atlantic Deep Water meets the colder and fresher Antarctic Bottom Water in the interior, where they exchange heat and salt before returning southwards as a unified flow. The separation of the overturning circulation by Lagrangian trajectories thus reveals how the components of the North Atlantic Ocean Circulation exchange heat and salt and thus have contrasting roles.

  • 324.
    Berglund, Sara
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Döös, Kristofer
    Stockholm University, Faculty of Science, Department of Meteorology .
    Groeskamp, Sjoerd
    NIOZ Royal Netherlands Institute for Sea Research, Den Burg, Texel, The Netherlands.
    McDougall, Trevor J.
    School of Mathematics and Statistics, University of New South Wales, Australia.
    The Downward Spiralling Nature of the North Atlantic Subtropical GyreManuscript (preprint) (Other academic)
    Abstract [en]

    The Atlantic Meridional Overturning Circulation (AMOC) regulates the heat distribution and climate of Earth. Here we identify a new feature of the circulation within the North Atlantic Subtropical Gyre that is associated with the northward flowing component of the AMOC.We find that 70% of the water that flows northwards as part of the AMOC circulates the Gyre at least once before it can continue northwards.These circuits are needed to achieve an increase of density and depth through a combination of air-sea interaction and interior mixing processes, before water can escape the latitudes of the Gyre and join the northern upper branch of the AMOC.This points towards an important role of the Gyre circulations in determining the strength and variability of the AMOC and the northward heat transport.Understanding this newly identified role of the North Atlantic Subtropical Gyre is needed to properly represent future changes of the AMOC. 

  • 325.
    Bergquist, Arne
    et al.
    Lantmäteriet.
    Brandt, S. Anders
    University of Gävle, Department of Technology and Built Environment, Ämnesavdelningen för samhällsbyggnad.
    Klang, Dan
    Vad är optimal kvalitet på geografisk information som underlag för detaljerad översvämningskartering?2008In: Kart & Bildteknik (Mapping and Image Science), ISSN 1651-792X, no 4, p. 18-20Article in journal (Other (popular science, discussion, etc.))
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  • 326.
    Bergstrand, Eriling
    et al.
    SMHI.
    Tobiasson, Stefan
    SMHI.
    Samordnade kustvattenkontrollen i Östergötland 19881989Report (Other academic)
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  • 327.
    Bergstrand, Erland
    et al.
    SMHI.
    Tobiasson, Stefan
    Recipientkontroll vid Breviksnäs fiskodling 19861987Report (Other academic)
    Abstract [sv]

    Christer Wastesson startade våren 1986 en fiskodling förregnbåge vid Breviksnäs i Valdemarsviks kommun. Länsstyrelsenhar godkänt recipientkontrollprogram enligtbilaga 1 att gälla första odlingssäsongen (1986). Programmettogs på Christer Wastessons uppdrag fram av SMHIoch Bertil Lindvall vid Kalmar Högskola. Programmetgenomfördes av SMHI i samarbete med Stefan Tobiasson,likasåvid Högskolan. Den löpande vattenprovtagning som ingår ikontrollen har utförts genom Christer Wastessons försorg.Föreliggande rapport redogör för genomförande ochresultat av kontrollprogrammet. Den biologiska delen harutförts av Stefan Tobiasson.

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  • 328.
    Bergstrand, Marie
    et al.
    SMHI, Core Services.
    Asp, Sara-Sofia
    SMHI, Core Services.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Nationwide hydrological statistics for Sweden with high resolution using the hydrological model S-HYPE2014In: HYDROLOGY RESEARCH, ISSN 1998-9563, Vol. 45, no 3, p. 349-356Article in journal (Refereed)
    Abstract [en]

    A first version of nationally covering hydrological statistics for Sweden based on the S-HYPE hydrological model for the period 1961-2010 is described. A key feature of the proposed method is that observed data are used as input wherever such data are available, and the model is used for interpolation in between stations. Short observation records are automatically extended by the use of the model. High flow statistics typically differed by about +/- 10% from observations. The corresponding number for low flow was about +/- 30%. High flow peaks were usually simulated slightly too low whereas low flows were too high. In a relative sense low flows were more uncertain than high flows. The mean flow was relatively certain. The annual maximum values were fitted to a Gumbel distribution, by the method of moments, for each subbasin. Flood statistics were then calculated up to a return period of 50 years. According to a Kolmogorov-Smirnov test, less than 1% of the fitted distributions were rejected. Most rejections occurred in regulated systems, due to difficulties in simulating regulation strategies, but also due to uncertainties in the precipitation input in the mountainous region. Results at small scale are very uncertain. The proposed method is a cost-effective way of calculating hydrological statistics with high spatial resolution.

  • 329.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hydrological controls on pelagic food structure: From shunts to chemostats as caused by runoff magnitudes and frequency of episodes2020In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 34, no 22, p. 4150-4155Article in journal (Refereed)
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  • 330.
    Bergström, Ann-Kristin
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Seasonal dynamics of bacteria and mixotrophic flagellates as related to input of allochthonous dissolved organic carbon2009In: International association of theoretical and applied limnology, vol 30, pt 6: proceedings / [ed] Jones, J & Faaborg, J, Stuttgart: Schweizerbart , 2009, p. 923-928Conference paper (Refereed)
  • 331.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Jan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Karlsson, Daniel
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vrede, Tobias
    Contrasting plankton stoichiometry and nutrient regeneration in northern arctic and boreal lakes2018In: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 80, no 2, article id 24Article in journal (Refereed)
    Abstract [en]

    Contrasting carbon: nitrogen: phosphorus (C: N: P) stoichiometry between phytoplankton and zooplankton affect consumer growth and phytoplankton nutrient limitation via nutrient recycling by zooplankton. However, no study has assessed how regional differences in terrestrial loadings of organic matter affect plankton N: P stoichiometry and recycling in systems with low N deposition and N-limited phytoplankton. We address this question by using data from 14 unproductive headwater arctic and boreal lakes. We found that boreal lakes had higher lake water-and seston C, N and P concentrations than arctic lakes, whereas seston C: N, C: P and N: P ratios did not differ among regions. Boreal zooplankton were also richer in N and P relative to C, with lower somatic N: P ratios, compared to arctic lakes. Consequently, the estimated N: P imbalances between seston and zooplankton were negative in arctic lakes, indicating zooplankton feeding on phytoplankton of suboptimal N content, resulting in low consumer driven N: P recycling (medians arctic sub-mid and high altitude lakes: 11 and 13). In boreal lakes, estimated N: P imbalance did not differ from zero, with a seston N: P stoichiometry matching the N: P requirements of zooplankton, which resulted in higher consumer driven N: P recycling (median 18). Our results imply that regional climate induced catchment differences, through enhanced terrestrial nutrient inputs, affect plankton stoichiometry by raising consumer N: P recycling ratio and changing zooplankton from being mainly N-(arctic) to NP co-limited (boreal). Browning of lakes, in regions with low N deposition, may therefore promote large-scale regional changes in plankton nutrient limitation with potential feedbacks on pelagic food webs.

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  • 332.
    Bergström, Ann-Kristin
    et al.
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Lau, Danny C. P.
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Isles, Peter D. F.
    Watershed Management Division, Vermont Department of Environmental Conservation, VT, Montpelier, United States.
    Jonsson, Anders
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Creed, Irena F.
    Department of Physical and Environmental Sciences, University of Toronto – Scarborough Campus, ON, Toronto, Canada.
    Biomass, community composition and N:P recycling ratios of zooplankton in northern high-latitude lakes with contrasting levels of N deposition and dissolved organic carbon2022In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 67, no 9, p. 1508-1520Article in journal (Refereed)
    Abstract [en]

    Global changes are causing decreases in inorganic nitrogen (N) concentrations, increases in coloured dissolved organic carbon (DOC) concentrations, and decreases in dissolved inorganic N to total phosphorus ratios (DIN:TP) in northern lakes. The effects of these changes on phytoplankton and zooplankton biomass and the N:P recycling ratio of zooplankton remain unresolved.

    In 33 Swedish headwater lakes across subarctic-to-boreal gradients with different levels of N deposition (low N in the north [Västerbotten, boreal; Abisko, subarctic] vs. high N in the south [Värmland, boreal; Jämtland, subarctic]), we measured water chemistry, phytoplankton biomass (chlorophyll-a [Chl-a], Chl-a:TP), seston mineral quality (C:P, N:P), as well as zooplankton biomass, community composition, and C:N:P stoichiometry. We estimated nutrient imbalances and the N:P recycling ratios of zooplankton using ecological stoichiometry models.

    There was a large-scale gradient from low lake DIN and DIN:TP in the north to high DIN and DIN:TP in the south, with lower DIN:TP in lakes coinciding with higher DOC within each region. Lower lake DIN was associated with lower phytoplankton biomass (lower Chl-a:TP). Lower lake DIN:TP was associated with richer seston mineral quality (lower seston C:P and N:P) and higher zooplankton biomass.

    Zooplankton community composition differed in the north vs. south, with a dominance of N-requiring calanoid copepods with high N:P in the north and P-requiring cladocerans with low N:P in the south. Also, greater differences in zooplankton community composition were found between subarctic regions (with lower DOC) than between boreal regions (with higher DOC), suggesting that increases in lake DOC and associated declines in lake DIN:TP reduce differences in zooplankton community composition.

    The combination of lower lake DIN, higher lake DOC, and lower lake DIN:TP led to reduced zooplankton N:P recycling ratios, possibly by reducing seston N:P and/or by enhancing calanoid copepod dominance in the zooplankton community.

    Our findings suggest that the combination of declining N deposition and increasing lake browning in northern high-latitude lakes will reduce phytoplankton biomass, but will concurrently enhance seston mineral quality and probably also zooplankton biomass and their recycling efficiency of P relative to N.

  • 333.
    Bergström, Ann-Kristin
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Lau, Danny C. P.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Isles, Peter D. F.
    Watershed Management Division, Vermont Department of Environmental Conservation, VT, Montpelier, United States.
    Jonsson, Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Creed, Irena F.
    Department of Physical and Environmental Sciences, University of Toronto – Scarborough Campus, ON, Toronto, Canada.
    Biomass, community composition and N:P recycling ratios of zooplankton in northern high-latitude lakes with contrasting levels of N deposition and dissolved organic carbon2022In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 67, no 9, p. 1508-1520Article in journal (Refereed)
    Abstract [en]
    1. Global changes are causing decreases in inorganic nitrogen (N) concentrations, increases in coloured dissolved organic carbon (DOC) concentrations, and decreases in dissolved inorganic N to total phosphorus ratios (DIN:TP) in northern lakes. The effects of these changes on phytoplankton and zooplankton biomass and the N:P recycling ratio of zooplankton remain unresolved.
    2. In 33 Swedish headwater lakes across subarctic-to-boreal gradients with different levels of N deposition (low N in the north [Västerbotten, boreal; Abisko, subarctic] vs. high N in the south [Värmland, boreal; Jämtland, subarctic]), we measured water chemistry, phytoplankton biomass (chlorophyll-a [Chl-a], Chl-a:TP), seston mineral quality (C:P, N:P), as well as zooplankton biomass, community composition, and C:N:P stoichiometry. We estimated nutrient imbalances and the N:P recycling ratios of zooplankton using ecological stoichiometry models.
    3. There was a large-scale gradient from low lake DIN and DIN:TP in the north to high DIN and DIN:TP in the south, with lower DIN:TP in lakes coinciding with higher DOC within each region. Lower lake DIN was associated with lower phytoplankton biomass (lower Chl-a:TP). Lower lake DIN:TP was associated with richer seston mineral quality (lower seston C:P and N:P) and higher zooplankton biomass.
    4. Zooplankton community composition differed in the north vs. south, with a dominance of N-requiring calanoid copepods with high N:P in the north and P-requiring cladocerans with low N:P in the south. Also, greater differences in zooplankton community composition were found between subarctic regions (with lower DOC) than between boreal regions (with higher DOC), suggesting that increases in lake DOC and associated declines in lake DIN:TP reduce differences in zooplankton community composition.
    5. The combination of lower lake DIN, higher lake DOC, and lower lake DIN:TP led to reduced zooplankton N:P recycling ratios, possibly by reducing seston N:P and/or by enhancing calanoid copepod dominance in the zooplankton community.
    6. Our findings suggest that the combination of declining N deposition and increasing lake browning in northern high-latitude lakes will reduce phytoplankton biomass, but will concurrently enhance seston mineral quality and probably also zooplankton biomass and their recycling efficiency of P relative to N.
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  • 334.
    Bergström, Carolin
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Vattenkemisk undersökning i Lissån2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The water chemistry in watercourses are constantly changing and processes such aswater flow, climate change and anthropogenic processes could affect the water’s chemical composition.

    The work has examined how the water chemistry changes in Lissån in the spring with respect to the electrical conductivity. It has also taken into account what sources in the catchment area that may affect a possible change in the electrical conductivity.

    During the thaw of the winter the flows in Uppsala streams will increase and will not subside until spring. This change in flow affects the water flow size, which in turn has a bearing on the electrical conductivity and the watercourses chemical composition. Within the catchment area you also find Hovgården waste plant which is a potential source of a possible change in the chemical composition in Lissån.Purified leachate from the plant is released into Hovgårdsbäcken which connects to the recipient Lissån and may be a cause of the changes in electrical conductivity.

    During the spring samples have been gathered in Lissån at Fribacken and these have been compared with samples taken where Hovgårdsbäcken intersects with Lissån. The water chemistry and the electrical conductivity in Lissån is concluded to be affected by the size of the water flow and to some extent also of the emissions from the waste plant.The results show that an increased water flow decreases the electrical conductivity. The water flow increases slightly with increased rainfall.

    The results show not only how anthropogenic processes such as emissions from waste plants can affect the water in rivers but also how climate change may affect water quality in the future.

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  • 335.
    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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  • 336.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    Parametervärden för HBV-modellen i Sverige: Erfarenheter från modellkalibreringar under perioden 1975-19891990Report (Other academic)
    Abstract [sv]

    HBV-modellen utvecklades vid SMHI i början av 1970-talet och har sedan dess funnit ett stort antal tillämpningar i landet. Inledningsvis var intresset mest knutet till hydrologisk prognosering åt vattenkraftindustrin och översvämningsvarningar till allmänheten, men under senare år har modellen fått spela en allt större roll för beräkning av dimensionerande flöden. Modellen finns i ett antal versioner, HBV-3, HBV-6 och HBV-TL samt ytterligare några för speciella tillämpningar. Dessutom finns ett antal versioner av modellen vid institutioner utanför SMHI såväl i Sverigesom utomlands.

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  • 337.
    Bergström, Sten
    SMHI, Research Department, Hydrology.
    PRINCIPLES AND CONFIDENCE IN HYDROLOGICAL MODELING1991In: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 22, no 2, p. 123-136Article in journal (Refereed)
    Abstract [en]

    General principles in development and application of hydrological models are discussed and related to the confidence in the results. The presentation is mainly based on the experience from the work with the HBV and PULSE models at the Swedish Meteorological and Hydrological Institute between 1971 and 1990 but has also been influenced by other modelling work. It covers a discussion on the optimal complexity of models, use of observations, calibration, control and sensitivity analysis. Special attention is given to the uncertainties encountered when using hydrological models for the simulation of extreme floods and long-term scenario simulations. Finally a few ethical problems in modelling are mentioned.

  • 338.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Brandt, Maja
    SMHI, Core Services.
    Gustafson, Arne
    SIMULATION OF RUNOFF AND NITROGEN LEACHING FROM 2 FIELDS IN SOUTHERN SWEDEN1987In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 32, no 2, p. 191-205Article in journal (Refereed)
  • 339.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Carlsson, Bengt
    SMHI, Research Department, Hydrology.
    Hydrology of the Baltic Basin: Inflow of fresh water from rivers and land for the period 1950–19901993Report (Other academic)
    Abstract [en]

    A data base of monthly inflow of fresh water from rivers and land to the Baltic Sea and its subbasins is created. The data base covers the period 1950 - 1990 and is based on observations from the national hydrological services of the surrounding countries.

    The main features of the data base are presented including river flow of selected rivers and total inflow to the Baltic Sea and its subbasins. Long term, seasonal and short term variabilities are analysed and the effects of hydropower development are identified. An earlier data base by Mikulski (1982) is used for comparison and extension of the record to cover the period 1921 - 1990.

    It is concluded that the variability of inflow is great and that the decade 1981 - 1990 is the wettest in 70 years. The increase in runoff is mainly due to increasing river flow during the cold seasons. The effects of hydropower development are noticeable in the records for the Bothnian Bay and the Bothnian Sea.

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  • 340.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Carlsson, Bengt
    SMHI, Research Department, Hydrology.
    RIVER RUNOFF TO THE BALTIC SEA - 1950-19901994In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 23, no 4-5, p. 280-287Article in journal (Refereed)
    Abstract [en]

    A database of monthly inflow of fresh water from rivers and land to the Baltic Sea and its subbasins is created. The database covers the period 1950-1990 and is based on observations from the national hydrological services of the surrounding countries. The main features of the database are presented including river flow of selected rivers and total inflow to the Baltic Sea and its subbasins. Long term, seasonal and short-term variabilities are analyzed and the effects of hydropower development are identified. An earlier database by Mikulski is used for comparison and extension of the record to cover the period 1921-1990. It is concluded that the variability of inflow is great and that the decade 1981-1990 was the wettest in 70 years. Wet years are also found in the 1920s. The increase in runoff is mainly due to increasing river flow during the cold seasons. The effects of hydropower development are noticeable in the records for the Bothnian Bay and the Bothnian Sea.

  • 341.
    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.

  • 342.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Ehlin, Ulf
    SMHI.
    Olsson, Per-Eric
    VASO.
    Riktlinjer och praxis vid dimensionering av utskov och dammar i USA: Rapport från en studieresa i oktober 19851986Report (Other academic)
    Abstract [sv]

    Under oktober månad 1985 företog vi en studieresa i USA på uppdrag av Flödeskommittén. Avsikten var att inhämta upplysningar om de riktlinjer, som tillämpas i USA för bestämning av dimensionerade flöden för utskov vid kraftverk och regleringsdammar. Inte minst viktigt var att genom personliga samtal med meteorologer, hydrologer och tekniker få ett grepp om metodernas fördelar och svagheter samt vilka subjektiva bedömningar, som påverkar beräkningsresultaten. Vi kom även att diskutera frågor om hydrologiska prognoser och datainsamlingssystem. 

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  • 343.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    Abstract to "On the scale problem in hydrological modelling" [Journal of Hydrology 211 (1998) 253-265]1999In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 217, no 3-4, p. 284-284Article in journal (Refereed)
  • 344.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Graham, Phil
    SMHI, Research Department, Climate research - Rossby Centre.
    On the scale problem in hydrological modelling1998In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 211, no 1-4, p. 253-265Article in journal (Refereed)
    Abstract [en]

    The problem of scales and particularly the modelling of macro or continental scale catchments in hydrology is addressed. It is concluded that the magnitude of the scale problem is related to the specific hydrologic problem to be solved and to the scientific approach and perspective of the modeller. A distributed modelling approach, based on variability parameters, is suggested for modelling of soil moisture dynamics and runoff generation. It is shown that the parameters of such an approach are relatively stable over a wide range of scales. An example of the application of a standard Version of the Swedish HBV hydrological model to the continental scale catchment of the Baltic Sea is shown and its usefulness is discussed. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • 345.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Harlin, Joakim
    SMHI.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    SPILLWAY DESIGN FLOODS IN SWEDEN .1. NEW GUIDELINES1992In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 37, no 5, p. 505-519Article in journal (Refereed)
    Abstract [en]

    The new Swedish guidelines for the estimation of design floods for dams and spillways are presented, with emphasis on high-hazard dams. The method is based on a set of regional design precipitation sequences, rescaled for basin area, season and elevation above sea level, and a full hydrological model. A reservoir operation strategy is also a fundamental component of the guidelines. The most critical combination of flood generating factors is searched by systematically inserting the design precipitation sequence into a ten year climatological record, where the initial snowpack has been replaced by a statistical 30-year snowpack. The new guidelines are applicable to single reservoir systems as well as more complex hydroelectric schemes, and cover snowmelt floods, rain floods and combinations of the two. In order to study the probabilities of the computed floods and to avoid regional inconsistencies, extensive comparisons with observed floods and frequency analyses have been carried out.

  • 346.
    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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  • 347.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Core Services.
    Interpretation of runoff processes in hydrological modelling experience from the HBV approach2015In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, no 16, p. 3535-3545Article in journal (Refereed)
    Abstract [en]

    The process of development and application of the Hydrologiska Byrans Vattenbalansavdelning hydrological model over a time period of more than 40years is reviewed and discussed. Emphasis is on the early modelling strategy and physical considerations based on contemporary research on runoff formation processes in the drainage basin. This includes areal considerations on the catchment scale, soil moisture and evapotranspiration and storages and discharge as represented by the response function of the model. The introduction of the concept of dynamic recharge and discharge areas is also addressed as well as the modelling of snow accumulation and melt. Some operational international experiences are also addressed. Copyright (c) 2015 John Wiley & Sons, Ltd.

  • 348.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Pettersson, Anna
    SMHI, Research Department, Hydrology.
    Multi-variable parameter estimation to increase confidence in hydrological modelling2002In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 16, no 2, p. 413-421Article in journal (Refereed)
    Abstract [en]

    The expanding use and increased complexity of hydrological runoff models has given rise to a concern about overparameterization and risks for compensating errors. One proposed way out is the calibration and validation against additional observations, such as snow, soil moisture, groundwater or water quality. A general problem, however, when calibrating the model against more than one variable is the strategy for parameter estimation. The most straightforward method is to calibrate the model components sequentially. Recent results show that in this way the model may be locked up in a parameter setting, which is good enough for one variable but excludes proper simulation of other variables. This is particularly the case for water quality modelling, where a small compromise in terms of runoff simulation may lead to dramatically better simulations of water quality. This calls for an integrated model calibration procedure with a criterion that integrates more aspects on model performance than just river runoff. The use of multi-variable parameter estimation and internal control of the HBV hydrological model is discussed and highlighted by two case studies. The first example is from a forested basin in northern Sweden and the second one is from an agricultural basin in the south of the country. A new calibration strategy, which is integrated rather than sequential, is proposed and tested. It is concluded that comparison of model results with more measurements than only runoff can lead to increased confidence in the physical relevance of the model, and that the new calibration strategy can be useful for further model development. Copyright (C) 2002 John Wiley Sons, Ltd.

  • 349.
    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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  • 350.
    Bernello, Giacomo
    et al.
    Department of Land, Environment, Agriculture and Forestry, University of Padova, Agripolis, Viale dell’Università 16, 35020 Legnaro, Italy.
    Mondino, Elena
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Institute for Environmental Sciences, University of Geneva, Uni Carl Vogt, 66 Boulevard Carl-Vogt, 1205 Geneva, Switzerland; Centre of Natural Hazards and Disaster Science (CNDS), Uppsala University, Villavägen 16, 752 36 Uppsala, Sweden.
    Bortolini, Lucia
    Department of Land, Environment, Agriculture and Forestry, University of Padova, Agripolis, Viale dell’Università 16, 35020 Legnaro, Italy.
    People’s Perception of Nature-Based Solutions for Flood Mitigation: The Case of Veneto Region (Italy)2022In: Sustainability, E-ISSN 2071-1050, Vol. 14, no 8, article id 4621Article in journal (Refereed)
    Abstract [en]

    Floods have become more frequent due to a growing number of extreme rainfall events linked to climate change and increased urbanization. Additionally, 66% of the world’s population is expected to live in urban areas by 2050, making flood prevention and risk reduction increasingly important. Sustainability, resilience and ecosystem services are essential to increase human well-being in urban environments. Nature-based Solutions (NBS) can provide all the benefits of urban green spaces combined with flood mitigation. This work aims to provide useful information to promote the adoption of NBS to build communities resilient to climate change by exploring how people’s perception of and willingness to implement some NBS. To this end, an online survey was conducted to investigate the knowledge and the perception of NBS and grey infrastructures among people in Veneto, a north-Eastern region of Italy. Data analysis revealed a significant correlation between previous knowledge of water management systems and the perceived effectiveness of some NBS. Behaviors linked to the level of connection with the territory have also been found to influence the perceived effectiveness of NBS. This study provides insights into the dynamics behind the implementation of NBS to reduce the risk of urban flooding and can help policymakers adapt urban plans to promote the adoption of NBS.

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