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  • 251.
    Bratt, Anna
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Andersson, L.
    Sandén, Per
    Linköping University, The Tema Institute. Linköping University, Faculty of Arts and Sciences.
    Farmers questions and model answers on nitrogen leakage2003Article in journal (Refereed)
  • 252.
    Bratt, Anna
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Graham, L. P.
    Sandén, Per
    Linköping University, The Tema Institute. Linköping University, Faculty of Arts and Sciences.
    Potential changes to nutrient leaching from adaptation of Swedish agricultural production to climate change2003Article in journal (Refereed)
  • 253.
    Bratt, Anna-Lena
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Managing agricultural nutrient leaching within the EC Water Framework Directive in Sweden2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Agricultural management practices geared towards reducing nutrient leaching are in focus for the research presented in this thesis. Critical measures for reducing diffuse pollution from the agricultural sector depend on decisions of individual farmers. It is useful to take stock of what different stakeholders are actually doing to reduce nutrient leaching and analyze their reasoning before defining a new administrative process. Stakeholder perceptions about potentials and problems concerning management of agricultural practices are analyzed with a systems approach using various analytical methods, and put in relation to the implementation of EC Water Framework Directive in Sweden. The methods used include surveys, focus group interviews, model comparison, sensitivity analyses and analyses of climate change implications.

    The results indicate a general positive attitude among stakeholders towards the main characteristics of the newly introduced directive. They also reveal that a move towards a pro-active process was perceived as an additional positive factor for the improvement of water quality, where specific activities and measures are carried out according to planning based on local assessments. The respondents pointed out that a national approach would put necessary pressure on local politicians to define environmental objectives and provide resources to fulfil them. The current findings indicate that decision making for farmers is a complex procedure and that the different factors need to be addressed in order to obtain a change in agricultural practices.

    Consistent legislation that is clear about power and rights is fundamental for cooperation to function when volunteerism and enthusiasm are absent. Environmental and socio-economic conditions change constantly, and administration has to be flexible to be able to adapt. Having access to and being able to use relevant data is only one important factor for stakeholder involvement. To give farmers the opportunity to further develop production towards reduced nutrient losses, appropriate information provided in all the right arenas is crucial.

  • 254.
    Bratt, Anna-Lena
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Municipal officers on implementing the EU Water Framework Directive in Sweden regarding agricultural nutrient flows2004In: Local Environment, ISSN 1354-9839, Vol. 9, no 1, 65-79 p.Article in journal (Refereed)
    Abstract [en]

    The article analyses the perceptions at municipal level of potentials and problems in implementing integrated catchment management of water resources as proposed in the EU Water Framework Directive, expressed in views on how to reduce nutrient leakage from agricultural production. Heads of environmental authorities, spatial planners and environmental officers are among the professionals that will be key actors when implementing the WFD at the local level. Using a process of active focus group interviews, officials from municipal environmental offices studied, reflected upon and discussed the suggested plan concerning their part of implementing WFD. The municipal officers stressed certain conditions that have to be met to implement WFD in a sustainable manner. The most important conditions are clear environmental goals and management plans with support in legislation, which would put the necessary pressure upon local politicians to prioritize the WFD and take action. The respondents perceived the WFD would offer a changed approach in work routines with farmers towards partnerships for sustainable water resource management.

  • 255. Brauer, C. C.
    et al.
    Teuling, A. J.
    Overeem, A.
    van der Velde, Y.
    Hydrology and Quantitative Water Management Group, Wageningen University, Wageningen, The Netherlands.
    Hazenberg, P.
    Warmerdam, P. M. M.
    Uijlenhoet, R.
    Anatomy of extraordinary rainfall and flash flood in a Dutch lowland catchment2011In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 15, 1991-2005 p.Article in journal (Refereed)
    Abstract [en]

    On 26 August 2010 the eastern part of The Netherlands and the bordering part of Germany were struck by a series of rainfall events lasting for more than a day. Over an area of 740 km(2) more than 120 mm of rainfall were observed in 24 h. This extreme event resulted in local flooding of city centres, highways and agricultural fields, and considerable financial loss. In this paper we report on the unprecedented flash flood triggered by this exceptionally heavy rainfall event in the 6.5 km(2) Hupsel Brook catchment, which has been the experimental watershed employed by Wageningen University since the 1960s. This study aims to improve our understanding of the dynamics of such lowland flash floods. We present a detailed hydrometeorological analysis of this extreme event, focusing on its synoptic meteorological characteristics, its space-time rainfall dynamics as observed with rain gauges, weather radar and a microwave link, as well as the measured soil moisture, groundwater and discharge response of the catchment. At the Hupsel Brook catchment 160 mm of rainfall was observed in 24 h, corresponding to an estimated return period of well over 1000 years. As a result, discharge at the catchment outlet increased from 4.4x10(-3) to nearly 5m(3) s(-1). Within 7 h discharge rose from 5x10(-2) to 4.5m(3) s(-1). The catchment response can be divided into four phases: (1) soil moisture reservoir filling, (2) groundwater response, (3) surface depression filling and surface runoff and (4) backwater feedback. The first 35mm of rainfall were stored in the soil without a significant increase in discharge. Relatively dry initial conditions (in comparison to those for past discharge extremes) prevented an even faster and more extreme hydrological response.

  • 256. Braun, Mattias
    et al.
    Schuler, Thomas
    Hock, Regine
    Brown, Ian
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Jackson, Miriam
    Comparison of remote sensing derived glacier facies maps with distributed mass balance modelling at Engabreen, northern Norway.2007In: International Association of Hydrological Sciences: Red book series, no 318, 126-134 p.Article in journal (Refereed)
    Abstract [en]

    Abstract Calibration and validation of glacier mass balance models typically rely on mass balance data derived from measurements at individual points, often along altitudinal gradients, thus neglecting

    much of the spatial variability of mass balance. Remote sensing data can provide useful additional spatially distributed information, e.g. on surface conditions such as bare ice area, firn cover extent, or snow. We developed a semi-automated procedure to derive glacier-facies maps from Landsat satellite images, and applied it to Engabreen, an outlet glacier from the Svartisen ice cap in northern Norway. These maps, discriminating between firn, snow and ice surfaces, are then used as a reference for mass balance modelling. Facies information shows a general agreement with the available few field observations and results obtained by distributed mass balance modelling. We conclude that Earth Observation products provide a powerful, although as yet poorly exploited tool, for calibration and validation of distributed mass balance models.

  • 257.
    Bravo, Andrea G.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bouchet, Sylvain
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Tolu, Julie
    Umea Univ, Dept Ecol & Environm Sci, SE-90187 Umea, Sweden..
    Bjorn, Erik
    Umea Univ, Dept Chem, SE-90187 Umea, Sweden..
    Mateos-Rivera, Alejandro
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Bertilsson, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology. Uppsala University, Science for Life Laboratory, SciLifeLab.
    Molecular composition of organic matter controls methylmercury formation in boreal lakes2017In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, 14255Article in journal (Refereed)
    Abstract [en]

    A detailed understanding of the formation of the potent neurotoxic methylmercury is needed to explain the large observed variability in methylmercury levels in aquatic systems. While it is known that organic matter interacts strongly with mercury, the role of organic matter composition in the formation of methylmercury in aquatic systems remains poorly understood. Here we show that phytoplankton-derived organic compounds enhance mercury methylation rates in boreal lake sediments through an overall increase of bacterial activity. Accordingly, in situ mercury methylation defines methylmercury levels in lake sediments strongly influenced by planktonic blooms. In contrast, sediments dominated by terrigenous organic matter inputs have far lower methylation rates but higher concentrations of methylmercury, suggesting that methylmercury was formed in the catchment and imported into lakes. Our findings demonstrate that the origin and molecular composition of organic matter are critical parameters to understand and predict methylmercury formation and accumulation in boreal lake sediments.

  • 258. Breinl, Korbinian
    Driving a lumped hydrological model with precipitation output from weather generators of different complexity2016In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 61, no 8, 1395-1414 p.Article in journal (Refereed)
    Abstract [en]

    This paper deals with the question of whether a lumped hydrological model driven with lumped daily precipitation time series from a univariate single-site weather generator can produce equally good results compared to using a multivariate multi-site weather generator, where synthetic precipitation is first generated at multiple sites and subsequently lumped. Three different weather generators were tested: a univariate “Richardson type” model, an adapted univariate Richardson type model with an improved reproduction of the autocorrelation of precipitation amounts and a semi-parametric multi-site weather generator. The three modelling systems were evaluated in two Alpine study areas by comparing the hydrological output with respect to monthly and daily statistics as well as extreme design flows. The application of a univariate Richardson type weather generator to lumped precipitation time series requires additional attention. Established parametric distribution functions for single-site precipitation turned out to be unsuitable for lumped precipitation time series and led to a large bias in the hydrological simulations. Combining a multi-site weather generator with a hydrological model produced the least bias.

  • 259.
    Breinl, Korbinian
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Di Baldassarre, Giuliano
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Girons Lopez, Marc
    Department of Geography, University of Zurich.
    Hagenlocher, Michael
    Institute for Environment and Human Security, United Nations University (UNU-EHS).
    Vico, Giulia
    Department of Crop Production Ecology, Swedish University of Agricultural Sciences.
    Rutgersson, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Can weather generation capture precipitation patterns across different climates, spatial scales and under data scarcity?2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, 5449Article in journal (Refereed)
    Abstract [en]

    Stochastic weather generators can generate very long time series of weather patterns, which are indispensable in earth sciences, ecology and climate research. Yet, both their potential and limitations remain largely unclear because past research has typically focused on eclectic case studies at small spatial scales in temperate climates. In addition, stochastic multi-site algorithms are usually not publicly available, making the reproducibility of results difficult. To overcome these limitations, we investigated the performance of the reduced-complexity multi-site precipitation generator TripleM across three different climatic regions in the United States. By resampling observations, we investigated for the first time the performance of a multi-site precipitation generator as a function of the extent of the gauge network and the network density. The definition of the role of the network density provides new insights into the applicability in data-poor contexts. The performance was assessed using nine different statistical metrics with main focus on the inter-annual variability of precipitation and the lengths of dry and wet spells. Among our study regions, our results indicate a more accurate performance in wet temperate climates compared to drier climates. Performance deficits are more marked at larger spatial scales due to the increasing heterogeneity of climatic conditions.

  • 260. Breinl, Korbinian
    et al.
    Strasser, Ulrich
    Bates, Paul D
    Kienberger, Stefan
    A joint modelling framework for daily extremes of river discharge and precipitation in urban areas2015In: Journal of Flood Risk Management, ISSN 1753-318X, E-ISSN 1753-318XArticle in journal (Refereed)
    Abstract [en]

    Human settlements are often at risk from multiple hydro-meteorological hazards, which include fluvial floods, short-time extreme precipitation (leading to ‘pluvial’ floods) or coastal floods. In the past, considerable scientific effort has been devoted to assessing fluvial floods. Only recently have methods been developed to assess the hazard and risk originating from pluvial phenomena, whereas little effort has been dedicated to joint approaches. The aim of this study was to develop a joint modelling framework for simulating daily extremes of river discharge and precipitation in urban areas. The basic framework is based on daily observations coupled with a novel precipitation disaggregation algorithm using nearest neighbour resampling combined with the method of fragments to overcome data limitations and facilitate its transferability. The framework generates dependent time series of river discharge and urban precipitation that allow for the identification of fluvial flood days (daily peak discharge), days of extreme precipitation potentially leading to pluvial phenomena (maximum hourly precipitation) and combined fluvial–pluvial flood days (combined time series). Critical thresholds for hourly extreme precipitation were derived from insurance and fire service data.

  • 261. Breinl, Korbinian
    et al.
    Turkington, Thea
    Stowasser, Markus
    Stochastic generation of multi-site daily precipitation for applications in risk management2013In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 498, 23-35 p.Article in journal (Refereed)
    Abstract [en]

    Unlike single-site precipitation generators, multi-site precipitation generators make it possible to reproduce the space–time variation of precipitation at several sites. The extension of single-site approaches to multiple sites is a challenging task, and has led to a large variety of different model philosophies for multi-site models. This paper presents an alternative semi-parametric multi-site model for daily precipitation that is straightforward and easy to implement. Multi-site precipitation occurrences are simulated with a univariate Markov process, removing the need for individual Markov models at each site. Precipitation amounts are generated by first resampling observed values, followed by sampling synthetic precipitation amounts from parametric distribution functions. These synthetic precipitation amounts are subsequently reshuffled according to the ranks of the resampled observations in order to maintain important statistical properties of the observation network. The proposed method successfully combines the advantages of non-parametric bootstrapping and parametric modeling techniques. It is applied to two small rain gauge networks in France (Ubaye catchment) and Austria/Germany (Salzach catchment) and is shown to well reproduce the observations. Limitations of the model relate to the bias of the reproduced seasonal standard deviation of precipitation and the underestimation of maximum dry spells. While the lag-1 autocorrelation is well reproduced for precipitation occurrences, it tends to be underestimated for precipitation amounts. The model can generate daily precipitation amounts exceeding the ones in the observations, which can be crucial for risk management related applications. Moreover, the model deals particularly well with the spatial variability of precipitation. Despite its straightforwardness, the new concept makes a good alternative for risk management related studies concerned with producing daily synthetic multi-site precipitation time series.

  • 262.
    Brentrup, Jennifer A.
    et al.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    Williamson, Craig E.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    Colom-Montero, William
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Eckert, Werner
    Yigal Allon Kinneret Limnol Lab, Israel Oceanog & Limnol Res, Migdal, Israel..
    de Eyto, Elvira
    Inst Marine, Newport, Mayo, Ireland..
    Grossart, Hans-Peter
    Leibniz Inst Freshwater Ecol & Inland Fisheries I, Dept Expt Limnol, Stechlin, Germany.;Univ Potsdam, Inst Biochem & Biol, Potsdam, Germany..
    Huot, Yannick
    Univ Sherbrooke, Dept Geomat Appl, Sherbrooke, PQ, Canada..
    Isles, Peter D. F.
    Univ Vermont, Rubenstein Sch Environm & Nat Resources, Burlington, VT USA..
    Knoll, Lesley B.
    Univ Minnesota, Itasca Biol Stn, Lake Itasca, MN USA..
    Leach, Taylor H.
    Miami Univ, Dept Biol, Oxford, OH 45056 USA..
    McBride, Chris G.
    Univ Waikato, Environm Res Inst, Waikato, New Zealand..
    Pierson, Don
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Limnology.
    Pomati, Francesco
    Swiss Fed Inst Aquat Sci & Technol, Dept Aquat Ecol, Dubendorf, Switzerland..
    Read, Jordan S.
    US Geol Survey, Ctr Integrated Data Analyt, Middleton, WI USA..
    Rose, Kevin C.
    Rensselaer Polytech Inst, Dept Biol Sci, Troy, NY USA..
    Samal, Nihar R.
    Univ New Hampshire, Earth Syst Res Ctr, Durham, NH 03824 USA..
    Staehr, Peter A.
    Aarhus Univ, Dept Biosci, Roskilde, Denmark..
    Winslow, Luke A.
    US Geol Survey, Ctr Integrated Data Analyt, Middleton, WI USA..
    The potential of high-frequency profiling to assess vertical and seasonal patterns of phytoplankton dynamics in lakes: an extension of the Plankton Ecology Group (PEG) model2016In: INLAND WATERS, ISSN 2044-2041, E-ISSN 2044-205X, Vol. 6, no 4, 565-580 p.Article in journal (Refereed)
    Abstract [en]

    The use of high-frequency sensors on profiling buoys to investigate physical, chemical, and biological processes in lakes is increasing rapidly. Profiling buoys with automated winches and sensors that collect high-frequency chlorophyll fluorescence (ChlF) profiles in 11 lakes in the Global Lake Ecological Observatory Network (GLEON) allowed the study of the vertical and temporal distribution of ChlF, including the formation of subsurface chlorophyll maxima (SSCM). The effectiveness of 3 methods for sampling phytoplankton distributions in lakes, including (1) manual profiles, (2) single-depth buoys, and (3) profiling buoys were assessed. High-frequency ChlF surface data and profiles were compared to predictions from the Plankton Ecology Group (PEG) model. The depth-integrated ChlF dynamics measured by the profiling buoy data revealed a greater complexity that neither conventional sampling nor the generalized PEG model captured. Conventional sampling techniques would have missed SSCM in 7 of 11 study lakes. Although surface-only ChlF data underestimated average water column ChlF, at times by nearly 2-fold in 4 of the lakes, overall there was a remarkable similarity between surface and mean water column data. Contrary to the PEG model's proposed negligible role for physical control of phytoplankton during the growing season, thermal structure and light availability were closely associated with ChlF seasonal depth distribution. Thus, an extension of the PEG model is proposed, with a new conceptual framework that explicitly includes physical metrics to better predict SSCM formation in lakes and highlight when profiling buoys are especially informative.

  • 263. Breuer, L.
    et al.
    Huisman, J. A.
    Willems, P.
    Bormann, H.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H. -G
    Graeff, T.
    Hubrechts, L.
    Jakeman, A. J.
    Kite, G.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Seibert, J.
    Sivapalan, M.
    Viney, N. R.
    Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM). I: Model intercomparison with current land use2009In: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, no 2, 129-146 p.Article in journal (Refereed)
    Abstract [en]

    This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations. (C) 2008 Elsevier Ltd. All rights reserved.

  • 264. Breuer, L.
    et al.
    Huisman, J. A.
    Willems, P.
    Bormann, H.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H. G.
    Graff, T.
    Hubrechts, L.
    Jakeman, A. J.
    Kite, G.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindstrom, G.
    Seibert, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Sivapalan, M.
    Viney, N. R.
    Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM). I: Model intercomparison with current land use2009In: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, no 2, 129-146 p.Article in journal (Refereed)
    Abstract [en]

    This paper introduces the project on 'Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM)' that aims at investigating the envelope of predictions on changes in hydrological fluxes due to land use change. As part of a series of four papers, this paper outlines the motivation and setup of LUCHEM, and presents a model intercomparison for the present-day simulation results. Such an intercomparison provides a valuable basis to investigate the effects of different model structures on model predictions and paves the ground for the analysis of the performance of multi-model ensembles and the reliability of the scenario predictions in companion papers. in this study, we applied a set of 10 lumped, semi-lumped and fully distributed hydrological models that have been previously used in land use change studies to the low mountainous Dill catchment. Germany. Substantial differences in model performance were observed with Nash-Sutcliffe efficiencies ranging from 0.53 to 0.92. Differences in model performance were attributed to (1) model input data, (2) model calibration and (3) the physical basis of the models. The models were applied with two sets of input data: an original and a homogenized data set. This homogenization of precipitation, temperature and leaf area index was performed to reduce the variation between the models. Homogenization improved the comparability of model simulations and resulted in a reduced average bias, although some variation in model data input remained. The effect of the physical differences between models on the long-term water balance was mainly attributed to differences in how models represent evapotranspiration. Semi-lumped and lumped conceptual models slightly outperformed the fully distributed and physically based models. This was attributed to the automatic model calibration typically used for this type of models. Overall, however, we conclude that there was no superior model if several measures of model performance are considered and that all models are suitable to participate in further multi-model ensemble set-ups and land use change scenario investigations.

  • 265. Brigode, Pierre
    et al.
    Brissette, Francois
    Nicault, Antoine
    Perreault, Luc
    Kuentz, Anna
    SMHI, Core Services.
    Mathevet, Thibault
    Gailhard, Joel
    Streamflow variability over the 1881-2011 period in northern Quebec: comparison of hydrological reconstructions based on tree rings and geopotential height field reanalysis2016In: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 12, no 9, 1785-1804 p.Article in journal (Refereed)
  • 266. Bring, A.
    et al.
    Fedorova, I.
    Dibike, Y.
    Hinzman, L.
    Mård, Johanna
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Mernild, S. H.
    Prowse, T.
    Semenova, O.
    Stuefer, S. L.
    Woo, M-K
    Arctic terrestrial hydrology: A synthesis of processes, regional effects, and research challenges2016In: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, no 3, 621-649 p.Article, review/survey (Refereed)
    Abstract [en]

    Terrestrial hydrology is central to the Arctic system and its freshwater circulation. Water transport and water constituents vary, however, across a very diverse geography. In this paper, which is a component of the Arctic Freshwater Synthesis, we review the central freshwater processes in the terrestrial Arctic drainage and how they function and change across seven hydrophysiographical regions (Arctic tundra, boreal plains, shield, mountains, grasslands, glaciers/ice caps, and wetlands). We also highlight links between terrestrial hydrology and other components of the Arctic freshwater system. In terms of key processes, snow cover extent and duration is generally decreasing on a pan-Arctic scale, but snow depth is likely to increase in the Arctic tundra. Evapotranspiration will likely increase overall, but as it is coupled to shifts in landscape characteristics, regional changes are uncertain and may vary over time. Streamflow will generally increase with increasing precipitation, but high and low flows may decrease in some regions. Continued permafrost thaw will trigger hydrological change in multiple ways, particularly through increasing connectivity between groundwater and surface water and changing water storage in lakes and soils, which will influence exchange of moisture with the atmosphere. Other effects of hydrological change include increased risks to infrastructure and water resource planning, ecosystem shifts, and growing flows of water, nutrients, sediment, and carbon to the ocean. Coordinated efforts in monitoring, modeling, and processing studies at various scales are required to improve the understanding of change, in particular at the interfaces between hydrology, atmosphere, ecology, resources, and oceans.

  • 267.
    Bring, Arvid
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Arctic Climate and Water Change: Information Relevance for Assessment and Adaptation2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Arctic is subject to growing economic and political interest. Meanwhile, its water and climate systems are in rapid transformation. Relevant and accessible information about water and climate is therefore vital to detect, understand and adapt to the changes. This thesis investigates hydrological monitoring systems, climate model data, and our understanding of hydro-climatic change, for adaptation to water system changes in the Arctic. Results indicate a lack of harmonized water chemistry data, which may impede efforts to understand transport and origin of key waterborne constituents. Further development of monitoring cannot rely only on a reconciliation of observations and projections on where climate change will be the most severe, as they diverge in this regard. Climate model simulations of drainage basin temperature and precipitation have improved between two recent model generations, but large inaccuracies remain for precipitation projections. Late 20th-century discharge changes in major Arctic rivers generally show excess of water relative to precipitation changes. This indicates a possible contribution of stored water from permafrost or groundwater to sea level rise. The river contribution to the increasing Arctic Ocean freshwater inflow matches that of glaciers, which underlines the importance of considering all sources when assessing change. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and made more accessible. This especially applies to hydrochemistry monitoring, where a more complete set of monitored basins is motivated, including a general extension for the large unmonitored areas close to the Arctic Ocean. Improvements in climate model parameterizations are needed, in particular for precipitation projections. Finally, further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers.

  • 268.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Divergent relevance and prioritization basis for hydro-climatic change monitoring in the Arctic2012Conference paper (Refereed)
    Abstract [en]

    Climate change affects society and the Earth System largely through water cycle changes, such as altered precipitation patterns and increased drought and flood pressures. In the Arctic, which undergoes a particularly large and rapid environmental transformation, information on water cycle changes is crucial to plan for societal adaptation. A prioritization strategy is then needed for how (where and when) monitoring should be focused to get the most relevant information and data on Arctic hydro-climatic change with limited available resources. We investigate different possible strategies for a geographic prioritization of hydro-climatic change monitoring in the Arctic. Results show conflicting prioritization basis across 14 major Arctic hydrological basins. The current monitoring density distribution is relevant for the so far observed but not for the projected future changes in Arctic climate. The present and the projected future hot-spots of greatest climate change differ, so that major spatial shifts must be anticipated in the future with regard to climate change severity across the Arctic. Important temporal shifts must further be anticipated in several major Arctic basins with currently decreasing but expected future increasing precipitation.

  • 269.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hydro-climatic change indications of Arctic permafrost thawing2012Conference paper (Refereed)
  • 270.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hydro-climatic changes and their monitoring in the Arctic: Observation-model comparisons and prioritization options for monitoring development2013In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 492, 273-280 p.Article in journal (Refereed)
    Abstract [en]

    The Arctic undergoes particularly large and rapid hydro-climatic changes, and information on hydrological responses to these changes is crucial to plan for societal adaptation. We investigate hydro-climatic change severity and monitoring in 14 major hydrological basins across the pan-Arctic, in view of different possible strategies for their monitoring prioritization. Results show that the current distribution of monitoring density in these basins is more relevant for so far observed precipitation changes than for observed temperature changes, or for projected future temperature and precipitation changes. Furthermore, present and projected future hot-spots of greatest hydro-climatic change differ spatially, so that major spatial shifts must occur in the future among the different Arctic basins in order for observations and climate model projections to converge with regard to hydro-climatic change severity. Also temporally, observation-model convergence requires that important change direction shifts occur in major Arctic basins, which have currently decreasing precipitation while model projections imply future increasing precipitation within them. Different prioritization options for rational development of hydro-climatic monitoring can be argued for based on the present results. The divergent prioritization options imply a need for an explicit strategy for achieving certain information goals, which must be selected from a larger set of different possible goals based on societal importance.

  • 271.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hydrological and hydrochemical observation status in the pan-Arctic drainage basin2009In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 28, 327-338 p.Article in journal (Refereed)
    Abstract [en]

    In order to identify and understand the ongoing changes in the Arctic hydrological cycle, and the impacts on the Arctic Ocean, timely and open access to water and water-chemistry data is essential. By synthesizing and analysing all openly accessible water-discharge and water-quality data, we present an updated, quantitative picture of the status of observational data on hydrological and hydrochemical fluxes from the pan-Arctic drainage basin (PADB) to the ocean. We identify and compare the characteristics of monitored and unmonitored areas, and the differences between them, across the continents in the PADB. Results indicate significant gaps in monitoring data for water chemistry, in particular for high-latitude near-coastal areas. The differences in characteristics between monitored and unmonitored areas may bias assessments of hydrological and hydrochemical fluxes to the Arctic Ocean. The reliable identification and understanding of important biogeochemical processes in the PADB require extended monitoring, particularly in high-latitude permafrost ground, and more ready access to harmonized and integrated hydrochemical data.

  • 272.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Information relevance for scenarios of Arctic climate and water change2013Conference paper (Refereed)
    Abstract [en]

    Relevant and accessible information about Arctic water and climate change is vital for scenario projection and adaptation in the rapidly changing region. We investigate the adequacy and relevance of hydrological monitoring systems, climate model data and hydro-climatic change understanding for formulation of change scenarios and adaptation to water system changes in the Arctic. Our results indicate a lack of harmonized water chemistry data for the pan-Arctic drainage basin, which may impede efforts at understanding transport and origin of key waterborne constituents and projecting their changes of relevance for water, climate and ecosystems. Furthermore, divergent distribution of observed and projected climate change severity poses challenges to prioritizing monitoring development. Climate model projections of drainage basin temperature and precipitation have improved between two successive model generations, but large inaccuracies remain for projected precipitation scenarios. Late 20th-century discharge changes in major Arctic rivers generally show excess of water relative to observed precipitation changes, indicating a possible contribution of stored water from permafrost or groundwater, even when considering data uncertainty on Arctic precipitation. To provide adequate information for research and policy, Arctic hydrological and hydrochemical monitoring needs to be extended, better integrated and more accessible, specifically regarding hydrochemistry with a more complete set of basins, and in general for the large unmonitored areas closer to the Arctic Ocean. Improvements in climate model parameterizations are needed in particular for precipitation projections, and further water-focused data and modeling efforts are required to resolve the source of excess discharge in Arctic rivers. 

  • 273.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Relevance of hydro-climatic change projection and monitoring for  assessment of water cycle changes in the Arctic2011Conference paper (Refereed)
    Abstract [en]

    Rapid changes to the Arctic hydrological cycle challenge both our process understanding and our ability to find appropriate adaptation strategies. We have investigated the relevance and accuracy development of climate change projections for assessment of water cycle changes in major Arctic drainage basins. Results show relatively good agreement of climate model projections with observed temperature changes, but high model inaccuracy relative to available observation data for precipitation changes. Direct observations further show systematically larger (smaller) runoff than precipitation increases (decreases). This result is partly attributable to uncertainties and systematic bias in precipitation observations, but still indicates that some of the observed increase in Arctic river runoff is due to water storage changes, for example melting permafrost and/or groundwater storage changes, within the drainage basins. Such causes of runoff change affect sea level, in addition to ocean salinity, and inland water resources, ecosystems and infrastructure. Process-based hydrological modeling and observations, which can resolve changes in evapotranspiration, and groundwater and permafrost storage at and below river basin scales, are needed in order to accurately interpret and translate climate-driven precipitation changes to changes in freshwater cycling and runoff. In contrast to this need, our results show that the density of Arctic runoff monitoring has become increasingly biased and less relevant by decreasing most and being lowest in river basins with the largest expected climatic changes.

  • 274.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Spatial patterns of decline in pan-arctic hydrological monitoring networks: a vulnerability map2008In: Northern Hydrology and its Global Role: XXV Nordic Hydrological Conference, 2008, 60-66 p.Conference paper (Refereed)
    Abstract [en]

    The last decades of observed rapid and significant changes to the Arctic hydrological system indicate an ongoing transition to a state not previously observed in recent history, which stresses the need for hydrological and hydrochemical observation networks that are adequate for detecting, understanding and modeling these changes. Recent studies have reported a widespread decline in these networks, but little information is available on where the decline has been most critical, and how it relates to the distribution of socio-economic and climatic pressures on water resources in the pan-Arctic drainage basin. We present a quantitative picture of the spatial patterns of decline in Arctic hydrological monitoring networks. We also analyze which Arctic drainage basins that are left most vulnerable by this decline, due to their combination with socio-economic and climate pressures. Results indicate that for basins where the hydrological monitoring decline has been higher than average, population density and economic production intensity are also frequently above average. Furthermore, diverging spatial patterns in future modeled and recently observed temperature trends makes it difficult to determine the real vulnerability of these basins to temperature change pressures.

  • 275.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hannerz, Fredrik
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Current status of Pan-Arctic hydrologic and hydrochemical observing networks2007In: Proceedings from the Arctic Coastal Zones at Risk workshop in Tromsö, Norway, 1-3 October 2007, 2007Conference paper (Other academic)
    Abstract [en]

    Access to reliable hydrologic and hydrochemical data is of paramount importance for accurately understanding and modeling ongoing change in the Arctic hydrologic cycle under a warming climate. Recent studies have shown that the availability of and accessibility to such data is limited, and also declining, for some Arctic areas. In particular, there is a lack of consistent monitoring of water chemistry. At the same time, there is little information on where and which data gaps are most critical.

    In light of the present decline of monitoring, it is important to compile and quantify the hydrological and water chemistry monitoring in the Arctic. It is further important to investigate whether there are any systematic differences in characteristics between monitored and unmonitored areas draining to the Arctic Ocean, as such biases might limit the ability of models to accurately predict hydrologic behavior across basins with different properties.

    We present a quantitative assessment of all openly available monitoring data for water discharge and important water chemistry parameters (carbon, nitrogen, phosphorus and sediment) in the pan-Arctic drainage basin.

    Openly accessible pan-Arctic monitoring data were assembled from various databases for discharge and water chemistry, and monitoring station locations were co-referenced to a 30-minute simulated topological network. This allowed the construction of a geographically distributed representation of the temporal and spatial extent of monitoring. By linking this information with spatially distributed basin properties, differences in characteristics between monitored and unmonitored areas were analyzed. Finally, spatial patterns in the recent decline of discharge monitoring were compared with recently observed and projected future temperature trends.

    Results indicate significant disparity in the spatial and temporal distribution of monitoring data, in particular for water chemistry monitoring, which is both spatially and temporally much less extensive than discharge monitoring. Additionally, there are systematic differences between the characteristics of monitored and unmonitored areas, within and between the different continents in the pan-Arctic drainage basin. The decline in network density has been greatest in four Eurasian basins. In these areas, recent observational temperature trends have been the smallest, while climate models predict the greatest future increases in these areas.

    The scarcity of water chemical data and the systematic differences in characteristics between monitored and unmonitored basins may limit the reliability of assessments of Arctic water and hydrochemical flux changes under a warming climate. Observed and modeled climate trends exhibit diverging spatial patterns, which makes it difficult to determine whether the basins with the greatest decline in discharge monitoring density are really the ones that will experience the greatest future temperature change. Arctic monitoring needs to be extended in certain areas to enable reliable characterization of hydrologic and hydro-chemical variability and change in the region.

  • 276.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hannerz, Fredrik
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pan-Arctic drainage basin monitoring: current status and potential significance for assessment of climate change effects and feedbacks2007In: Proceedings of the Third International Conference on Climate & Water, 2007, 88-93 p.Conference paper (Other academic)
    Abstract [en]

    Access to reliable hydrologic data is of paramount importance for accurately understanding and modeling ongoing change in and climate feedbacks of the Arctic hydrologic cycle. The accessibility to such data is limited, and continues to decline for some Arctic areas, but there is little information on where and which data gaps are most critical. We present a quantitative assessment of openly accessible monitoring data for water discharge and chemistry in the pan-Arctic drainage basin. We also quantify differences in characteristics between monitored and unmonitored areas, and analyze spatial patterns in reported decline of discharge networks in relation to recently observed and future modeled temperature trends. Results indicate that there is significant disparity in the spatial and temporal distribution of monitoring data, in particular for water chemistry monitoring. Additionally, there are systematic differences between the characteristics of monitored and unmonitored areas, within and between the different continents in the pan-Arctic drainage basin. Discharge network density has declined the most in four Eurasian drainage basins, which show the smallest recently observed temperature trends but the greatest modeled future temperature changes. Differences in characteristics between monitored and unmonitored areas may limit the reliability of assessments of Arctic water and solute flux change under a warming climate. Arctic monitoring needs to be extended in certain areas to fully enable characterization of the hydrologic variability and change in the region.

  • 277.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hannerz, Fredrik
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pan-Arctic Drainage Basin Monitoring: Current Status and Potential Significance for Assessment of Climate Change Impacts and Feedbacks2007In: Arctic Forum Abstract Volume, 2007Conference paper (Other academic)
    Abstract [en]

    Access to reliable hydrologic data is of paramount importance for the accurate understanding of changes in the arctic hydrologic cycle, and is also vital to policymakers as a base for sound environmental decisions. Accessibility to such data is limited and continues to decline for some arctic areas, while little information exists on which data gaps are most critical. This study presents a quantitative assessment of openly available monitoring data for water discharge and chemistry in the pan-arctic drainage basin. Results indicate that there is significant disparity in the spatial and temporal distribution of accessible monitoring data, in particular for water chemistry monitoring. Additionally, there are systematic differences between the characteristics of monitored and unmonitored areas. These differences may limit the reliability of assessments of arctic water and solute flux changes under a warming climate. Arctic monitoring needs to be extended in certain areas, and data needs to be disseminated more efficiently, to fully enable characterization of the hydrologic variability and change in the region.

  • 278.
    Bring, Arvid
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Hannerz, Fredrik
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Pan-Arctic drainage basin observation networks: current status and potential significance for assessment of climate change effects and feedbacks2007In: 1st IPY workshop on Sustaining Arctic Observing Networks, 2007Conference paper (Other academic)
    Abstract [en]

    Hydrological observation networks are integral for understanding and modeling present and future changes in and climate feedbacks to the Arctic environmental system. Recent studies have reported a widespread decline in these networks, but patterns of decline and location of critical data gaps are less certain. We present an updated and quantitative status of openly accessible observation network data for discharge and water chemistry in the pan-Arctic drainage area. We also compare relevant hydrological and socio-economic characteristics of monitored and unmonitored areas, and analyze the decline in network density in relation to recently observed and future modeled temperature trends. Results indicate that there are significant temporal and spatial variations in accessible data, and that there is a critical lack of accessible water chemistry data for large shares of the pan-Arctic. Furthermore, there are systematic differences in characteristics between monitored and unmonitored areas, within and between pan-Arctic regions. Discharge network density has declined the most in four Eurasian drainage basins, which show the smallest recently observed temperature trends but the greatest modeled future temperature changes. Differences in characteristics between monitored and unmonitored areas may limit the reliability of assessments of Arctic water and solute flux change under a warming climate. Improved understanding of the Arctic hydrological system requires less restricted access to monitoring data, extended network coverage of unmonitored areas, and a commitment to sustaining and improving existing networks.

  • 279.
    Brodeau, Laurent
    et al.
    LEGI, France.
    Barnier, B.
    Treguier, A. -M
    Penduff, T
    Gulev, S.
    An ERA40-based atmospheric forcing for global ocean circulation models2010In: Ocean Modelling, ISSN 1463-5003, E-ISSN 1463-5011, Vol. 31, no 3-4, 88-104 p.Article in journal (Refereed)
    Abstract [en]

    We develop, calibrate and test a dataset intended to drive global ocean hindcasts simulations of the last five decades. This dataset provides surface meteorological variables needed to estimate air-sea fluxes and is built from 6-hourly surface atmospheric state variables of ERA40. We first compare the raw fields of ERA40 to the CORE.v1 dataset of Large and Yeager (2004), used here as a reference, and discuss our choice to use daily radiative fluxes and monthly precipitation products extracted from satellite data rather than their ERA40 counterparts. Both datasets lead to excessively high global imbalances of heat and freshwater fluxes when tested with a prescribed climatological sea surface temperature. After identifying unrealistic time discontinuities (induced by changes in the nature of assimilated observations) and obvious global and regional biases in ERA40 fields (by comparison to high quality observations), we propose a set of corrections. Tropical surface air humidity is decreased from 1979 onward, representation of Arctic surface air temperature is improved using recent observations and the wind is globally increased. These corrections lead to a significant decrease of the excessive positive global imbalance of heat. Radiation and precipitation fields are then submitted to a small adjustment (in zonal mean) that yields a near-zero global imbalance of heat and freshwater. A set of 47-year-long simulations is carried out with the coarse-resolution (2° × 2°) version of the NEMO OGCM to assess the sensitivity of the model to the proposed corrections. Model results show that each of the proposed correction contributes to improve the representation of central features of the global ocean circulation.

  • 280.
    Brodeau, Laurent
    et al.
    Stockholm University, Faculty of Science, Department of Meteorology .
    Koenigk, Torben
    Extinction of the northern oceanic deep convection in an ensemble of climate model simulations of the 20th and 21st centuries2016In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, no 9, 2863-2882 p.Article in journal (Refereed)
    Abstract [en]

    We study the variability and the evolution of oceanic deep convection in the northern North Atlantic and the Nordic Seas from 1850 to 2100 using an ensemble of 12 climate model simulations with EC-Earth. During the historical period, the model shows a realistic localization of the main sites of deep convection, with the Labrador Sea accounting for most of the deep convective mixing in the northern hemisphere. Labrador convection is partly driven by the NAO (correlation of 0.6) and controls part of the variability of the AMOC at the decadal time scale (correlation of 0.6 when convection leads by 3-4 years). Deep convective activity in the Labrador Sea starts to decline and to become shallower in the beginning of the twentieth century.  The decline is primarily caused by a decrease of the sensible heat loss to the atmosphere in winter resulting from increasingly warm atmospheric conditions. It occurs stepwise and is mainly the consequence of two severe drops in deep convective activity during the 1920s and the 1990s.  These two events can both be linked to the low-frequency variability of the NAO. A warming of the sub-surface, resulting from reduced convective mixing, combines with an increasing influx of freshwater from the Nordic Seas to rapidly strengthen the surface stratification and prevent any possible resurgence of deep convection in the Labrador Sea after the 2020s. Deep convection in the Greenland Sea starts to decline in the 2020s, until complete extinction in 2100. As a response to the extinction of deep convection in the Labrador and Greenland Seas, the AMOC undergoes a linear decline at a rate of about -0.3 Sv per decade during the twenty-first century.

  • 281.
    Broman, Barry
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Hammarklint, Thomas
    Rannat, Kalev
    Soomere, Tarmo
    Valdmann, Ain
    Trends and extremes of wave fields in the north-eastern part of the Baltic Proper2006In: Oceanologia, ISSN 0078-3234, Vol. 48, 165-184 p.Article in journal (Refereed)
    Abstract [en]

    The paper analyses one of the longest contemporary wave measurements in the northern Baltic Sea, performed at Almagrundet 1978-2003. This record contains the roughest instrumentally measured wave conditions (significant wave height = c. 7.8 m) in the northern Baltic Proper until December 2004. The data for the years 1979-95, the period for which the data are the most reliable, show a linear rising trend of 1.8% per annum in the average wave height. The seasonal variation in wave activity follows the variation in wind speed. The monthly mean significant wave height varies from 0.5 m in May-July to 1.3-1.4 m in December-January. No corrections have been made in the analysis to compensate for missing values, for their uneven distribution, or for ice cover.

  • 282. Bruen, M.
    et al.
    Krahe, P.
    Zappa, M.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Vehvilainen, B.
    Kok, K.
    Daamen, K.
    Visualizing flood forecasting uncertainty: some current European EPS platforms-COST731 working group 32010In: Atmospheric Science Letters, ISSN 1530-261X, E-ISSN 1530-261X, Vol. 11, no 2, 92-99 p.Article in journal (Refereed)
    Abstract [en]

    Cooperation in Science and Technology (COST) funding allows European scientists to establish international links, communicate their work to colleagues, and promote international research cooperation. COST731 was established to study the propagation of uncertainty from hydrometeorological observations through meteorological and hydrological models to the final flood forecast. Our focus is on how information about uncertainty is presented to the end user and how it is used. COST731 has assembled a number of demonstrations/case studies that illustrate a variety of practical approaches and these are presented here. While there is yet no consensus on how such information is presented, many end users do find it useful. Copyright (C) 2010 Royal Meteorological Society

  • 283.
    Brunner, Manuela I.
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Univ Grenoble Alpes, Grenoble INP, Grenoble, France..
    Viviroli, Daniel
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Belop GmbH, Sarnen, Switzerland..
    Sikorska, Anna E.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Warsaw Univ Life Sci, Dept Hydraul Engn, Warsaw, Poland..
    Vannier, Olivier
    Compagnie Natl Rhone, Lyon, France..
    Favre, Anne-Catherine
    Univ Grenoble Alpes, Grenoble INP, Grenoble, France..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Flood type specific construction of synthetic design hydrographs2017In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 53, no 2, 1390-1406 p.Article in journal (Refereed)
    Abstract [en]

    Accurate estimates of flood peaks, corresponding volumes, and hydrographs are required to design safe and cost-effective hydraulic structures. In this paper, we propose a statistical approach for the estimation of the design variables peak and volume by constructing synthetic design hydrographs for different flood types such as flash-floods, short-rain floods, long-rain floods, and rain-on-snow floods. Our approach relies on the fitting of probability density functions to observed flood hydrographs of a certain flood type and accounts for the dependence between peak discharge and flood volume. It makes use of the statistical information contained in the data and retains the process information of the flood type. The method was tested based on data from 39 mesoscale catchments in Switzerland and provides catchment specific and flood type specific synthetic design hydrographs for all of these catchments. We demonstrate that flood type specific synthetic design hydrographs are meaningful in flood-risk management when combined with knowledge on the seasonality and the frequency of different flood types.

  • 284.
    Brunner, Manuela Irene
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Univ Grenoble Alpes, ENSE, G INP, LTHE, Grenoble, France..
    Seibert, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Favre, Anne-Catherine
    Univ Grenoble Alpes, ENSE, G INP, LTHE, Grenoble, France..
    Bivariate return periods and their importance for flood peak and volume estimation2016In: Wine Economics and Policy, ISSN 1934-5070, E-ISSN 2049-1948, Vol. 3, no 6, 819-833 p.Article in journal (Refereed)
    Abstract [en]

    Estimates of flood event magnitudes with a certain return period are required for the design of hydraulic structures. While the return period is clearly defined in a univariate context, its definition is more challenging when the problem at hand requires considering the dependence between two or more variables in a multivariate framework. Several ways of defining a multivariate return period have been proposed in the literature, which all rely on different probability concepts. Definitions use the conditional probability, the joint probability, or can be based on the Kendall's distribution or survival function. In this study, we give a comprehensive overview on the tools that are available to define a return period in a multivariate context. We especially address engineers, practitioners, and people who are new to the topic and provide them with an accessible introduction to the topic. We outline the theoretical background that is needed when one is in a multivariate setting and present the reader with different definitions for a bivariate return period. Here, we focus on flood events and the different probability concepts are explained with a pedagogical, illustrative example of a flood event characterized by the two variables peak discharge and flood volume. The choice of the return period has an important effect on the magnitude of the design variable quantiles, which is illustrated with a case study in Switzerland. However, this choice is not arbitrary and depends on the problem at hand.

  • 285.
    Bryhn, Andreas C.
    et al.
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    Dimberg, Peter H.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Bergström, Lena
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    Fredriksson, Ronny E.
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    Mattila, Johanna
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    Bergstrom, Ulf
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    External nutrient loading from land, sea and atmosphere to all 656 Swedish coastal water bodies2017In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 114, no 2, 664-670 p.Article in journal (Refereed)
    Abstract [en]

    Identifying the main sources of nutrient loading is a key factor for efficient mitigation of eutrophication. This study has investigated the pathways of external nutrient loading to 656 coastal water bodies along the entire Swedish coastline. The studied water bodies have been delineated to meet requirements in the European Union's Water Framework Directive, and recent status assessments have shown that 57% of them fail to attain good or high ecological status with respect to nutrients. The analysis in the study was performed on data from mass balance based nutrient budgets computed using the modelling framework Vattenwebb. The external nutrient contribution from the sea to the water bodies was highly variable, ranging from about 1% to nearly 100%, but the median contribution was >99% of the total external loading regarding both nitrogen and phosphorus. External loading from the atmosphere and local catchment area played a minor role in general. However, 45 coastal water bodies received >25% of the external nitrogen and phosphorus from their catchments. Loading from land typically peaked in April following ice-break and snow melting and was comparatively low during summer. The results indicate that for many eutrophicated Swedish coastal water bodies, nutrient abatement is likely to be optimally effective when potential measures in all of the catchment area of the concerned sea basin are considered. Local-scale mitigation in single water bodies will likely be locally effective only in the small proportion of areas where water and thereby also nutrient input from the catchment is high compared to the influx from the sea. Future studies should include nutrient reduction scenarios in order to refine these conclusions and to identify relevant spatial scales for coastal eutrophication mitigation measures from a water body perspective.

  • 286.
    Bryhn, Andreas Christoffer
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Trends in Total Phosphorus Loadings and Concentrations Regarding Surface Waters of the Baltic Sea, 1968-20072010In: The Open Oceanography Journal, ISSN 1874-2521, Vol. 4, 1-8 p.Article in journal (Refereed)
    Abstract [en]

    The Baltic Sea, a large estuarine sea in northern Europe, has for many decades displayed obvious signs of anthropogeniceutrophication. This study relates long-term trends in total phosphorus (TP) loadings and TP concentrationsin surface waters regarding five major sub-basins of the Baltic Sea; the Bothnian Bay, the Bothnian Sea, the Baltic Proper,the Gulf of Finland and the Gulf of Riga. The longest time series ever published on these variables was developed andused for this purpose. TP loadings to these waters have decreased greatly and significantly since the 1980s. However, TPconcentrations have only decreased slightly in one of the sub-basins while concentrations have increased in the other fourbasins. Four possible hypotheses about the weak connection between TP loadings and concentrations are 1) increasing TPconcentration is a delayed effect from many decades of intensive TP loading, 2) fewer saline inflows of high intensityhave decreased sedimentation rates and increased TP concentrations, 3) fewer oxygen-rich saline inflows of high intensityhave increased TP diffusion from deep sediments to the whole water column and 4) less ice in the winter has increased theerosion and resuspension of shallow sediments and increased TP concentrations.

  • 287.
    Brüchert, Volker
    et al.
    Stockholm University, Faculty of Science, Department of Geology and Geochemistry.
    Currie, Bronwen
    Ministry of Fisheries and Marine Resources, Swakopmund, Namibia.
    Peard, Kathleen R
    Ministry of Fisheries and Marine Resources, Luderitz, Namibia.
    Hydrogen sulphide and methane emissions on the central Namibian shelf2009In: Progress in Oceanography, ISSN 0079-6611, E-ISSN 1873-4472, Vol. 83, no 1-4, 169-179 p.Article in journal (Refereed)
    Abstract [en]

    Hydrogen sulphide occurs frequently in the waters of the inner shelf coastal upwelling area off central Namibia. The area affected coincides with hatching grounds of commercially important pelagic fish, whose recruitment may be severely affected by recurring toxic sulphidic episodes. Both episodic biogenic methane gas-driven advective and molecular diffusive flux of hydrogen sulphide have been implicated as transport mechanisms from the underlying organic-matter-rich diatomaceous mud. To test hypotheses on the controls of hydrogen sulphide transport from the sediments on the inner Namibian shelf, water column and sediment data were acquired from four stations between 27 and 72 m water depth over a 3 year long period. On 14 cruises, temperature, salinity, dissolved oxygen, nitrate, methane, and total dissolved sulphide were determined from water column samples, and pore water dissolved methane, total dissolved sulphide, biomass of benthic sulphide-oxidising bacteria Beggiatoa and Thiomargarita, and bacterial sulphate reduction rates were determined from sediment cores. Superimposed on a trend of synchronous changes in water column oxygen and nutrient concentrations controlled by regional hydrographic conditions were asynchronous small-scale variations at the in-shore stations that attest to localized controls on water column chemistry. Small temporal variations in sulphate reduction rates determined with 35S-labeled sulphate do not support the interpretation that variable emissions of sulphide and methane from sediments are driven by temporal changes in the degradation rates of freshly deposited organic matter. The large temporal changes in the concentrations of hydrogen sulphide and the co-occurrence of pore water sulphate and methane support an interpretation of episodic advection of methane and hydrogen sulphide from deeper sediment depths – possibly due to gas bubble transport. Effective fluxes of hydrogen sulphide and methane to the water column, and methane and sulphide concentrations in the bottom waters were decoupled, likely due to the activity of sulphide-oxidising bacteria. While the causal mechanism for the episodic fluctuations in methane and dissolved sulphide concentrations remains unclear, this data set points to the importance of alternating advective and diffusive transport of methane and hydrogen sulphide to the water column.

  • 288.
    Buapet, Pimchanok
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Prince Songkla University, Thailand.
    Gullström, Martin
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Photosynthetic activity of seagrasses and macroalgae in temperate shallow waters can alter seawater pH and total inorganic carbon content at the scale of a coastal embayment2013In: Marine and Freshwater Research, ISSN 1323-1650, E-ISSN 1448-6059, Vol. 64, no 11, 1040-1048 p.Article in journal (Refereed)
    Abstract [en]

    Many studies have reported fluctuations in pH and the concentration of dissolved inorganic carbon (DIC) in shallow coastal waters as a result of photosynthetic activity; however, little is known about how these fluctuations vary with degree of exposure among habitats, and at different scales. In the present study, diel variation in seawater pH was apparent in aquaria experiments with Zostera marina and Ruppia maritima. These pH variations were affected by light regime, biomass level and plant species. Subsequently, the natural variability in seawater pH and the concentration of DIC was assessed in six shallow embayments (three sheltered and three exposed) during sunny days. From the outer part towards the interior part of each bay, the following four habitats were identified and studied: the bay-mouth open water, seagrass beds, mixed macrophyte belts and unvegetated bottoms. The two vegetated habitats and unvegetated bottoms were characterised by higher pH and a lower concentration of DIC than in the bay-mouth water. The mixed macrophytes habitat showed slightly higher pH and a lower concentration of DIC than the seagrass and unvegetated habitats. No significant effect of exposure was detected. Our findings clearly showed that the photosynthetic activity of marine macrophytes can alter the coastal pH and the concentration of DIC and that the effects can be observed at the scale of a whole bay.

  • 289. Buchecker, M.
    et al.
    Salvini, G.
    Di Baldassarre, Giuliano
    UNESCO-IHE Institute for Water Education, Delft, the Netherlands.
    Semenzin, E.
    Maidl, E.
    Marcomini, A.
    The role of risk perception in making flood risk management more effective2013In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 13, 3013-3030 p.Article in journal (Refereed)
    Abstract [en]

    Over the last few decades, Europe has suffered from a number of severe flood events and, as a result, there has been a growing interest in probing alternative approaches to managing flood risk via prevention measures. A literature review reveals that, although in the last decades risk evaluation has been recognized as key element of risk management, and risk assessment methodologies (including risk analysis and evaluation) have been improved by including social, economic, cultural, historical and political conditions, the theoretical schemes are not yet applied in practice. One main reason for this shortcoming is that risk perception literature is mainly of universal and theoretical nature and cannot provide the necessary details to implement a comprehensive risk evaluation. This paper therefore aims to explore a procedure that allows the inclusion of stakeholders' perceptions of prevention measures in risk assessment. It proposes to adopt methods of risk communication (both one-way and two-way communication) in risk assessment with the final aim of making flood risk management more effective. The proposed procedure not only focuses on the effect of discursive risk communication on risk perception, and on achieving a shared assessment of the prevention alternatives, but also considers the effects of the communication process on perceived uncertainties, accepted risk levels, and trust in the managing institutions.

    The effectiveness of this combined procedure has been studied and illustrated using the example of the participatory flood prevention assessment process on the Sihl River in Zurich, Switzerland. The main findings of the case study suggest that the proposed procedure performed well, but that it needs some adaptations for it to be applicable in different contexts and to allow a (semi-) quantitative estimation of risk perception to be used as an indicator of adaptive capacity.

  • 290. Buffam, Ishi
    et al.
    Laudon, Hjalmar
    Temnerud, Johan
    Örebro University, Department of Natural Sciences.
    Morth, Carl-Magnus
    Bishop, Kevin
    Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network2007In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, no G1, G01022- p.Article in journal (Refereed)
    Abstract [en]

    Acidity is well known to influence stream biota, but the less well-studied spatial and temporal distributions of acidity are likely to play a larger ecological role than average values. We present data on spatial variability of chemical parameters contributing to acidity during winter baseflow and spring flood periods in Krycklan, a fourth-order boreal stream network in northern Sweden. Fifteen stream sites were monitored in subcatchments spanning 3 orders of magnitude in size and representing a wide range of percent wetland. At baseflow, pH ranged from 3.9 to 6.5 at the different sites. Baseflow dissolved organic carbon (DOC) concentration varied by an order of magnitude and was positively correlated with subcatchment percent wetland, resulting in high spatial variability in dissociated organic acids (OA(-)). During spring flood, DOC and OA(-) increased in forested sites and decreased in wetland sites, resulting in reduced spatial variability in their concentrations. In contrast, base cations and strong acid anions diluted throughout the stream network, resulting in decreased acid neutralizing capacity (ANC) at all sites. The spatial variability of base cations increased slightly with high flow. As a result of the changes in OA(-) and ANC, pH dropped at all but the most acidic site, giving a slightly narrowed pH range during spring flood (4.2-6.1). The transition from winter to spring flood stream chemistry could largely be explained by: (1) a shift from mineral to upper riparian organic soil flow paths in forested catchments and (2) dilution of peat water with snowmelt in wetland catchments.

  • 291. Bulbul, A.
    et al.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Huq, S.M.I.
    Gunaratna, K.R.
    Arsenic uptake by fresh water green alga, Chlamydomonas2008In: Groundwater for Sustainable Development: Problems, Perspectives and Challenges / [ed] Bhattacharya, P., Ramanathan, AL., Mukherjee A.B., Bundschuh, J., Chandrasekharam, D. Keshari, A.K., The Netherlands: Taylor and Francis/A. A. Balkema , 2008, 389-396 p.Chapter in book (Refereed)
  • 292.
    Bundschuh, Jochen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630).
    Bhattacharya, ProsunKTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering (moved 20130630), Environmental Geochemistry and Ecotechnology.Chandrashekharam, D.
    Natural Arsenic in Groundwater: Occurrence, Remediation and Management2005Collection (editor) (Refereed)
  • 293.
    Bundschuh, Jochen
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering.
    Bhattacharya, Prosun
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    von Brömssen, Mattias
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Jakariya, Md
    Jacks, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Geochemistry and Ecotechnology.
    Thunvik, Roger
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Litter, M.I.
    Garcia, M.E.
    Arsenic-safe aquifers as a socially acceptable source of safe drinking water: What can rural Latin America learn from Bangladesh experiences?2009In: Natural Arsenic in Groundwater of Latin America: Occurrence, health impact and remediation, The Netherlands: CRC Press/Balkema , 2009, 677-685 p.Chapter in book (Refereed)
  • 294.
    Bunse, Carina
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Bacterioplankton in the light of seasonality and environmental drivers2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Bacterioplankton are keystone organisms in marine ecosystems. They are important for element cycles, by transforming dissolved organic carbon and other nutrients. Bacterioplankton community composition and productivity rates change in surface waters over spatial and temporal scales. Yet, many underlying biological processes determining when, why and how bacterioplankton react to changes in environmental conditions are poorly understood. Here, I used experiments with model bacteria and natural assemblages as well as field studies to determine molecular, physiological and ecological responses allowing marine bacteria to adapt to their environment.

    Experiments with the flavobacterium Dokdonia sp. MED134 aimed to determine how the metabolism of bacteria is influenced by light and different organic matter. Under light exposure, Dokdonia sp. MED134 expressed proteorhodopsin and adjusted its metabolism to use resources more efficiently when growing with lower-quality organic matter. Similar expression patterns were found in oceanic datasets, implying a global importance of photoheterotrophic metabolisms for the ecology of bacterioplankton.

    Further, I investigated how the composition and physiology of bacterial assemblages are affected by elevated CO2 concentrations and inorganic nutrients. In a large-scale experiment, bacterioplankton could keep productivity and community structure unaltered by adapting the gene expression under CO2 stress. To maintain pH homeostasis, bacteria induced higher expression of genes related to respiration, membrane transport and light acquisition under low-nutrient conditions. Under high-nutrient conditions with phytoplankton blooms, such regulatory mechanisms were not necessary. These findings indicate that open ocean systems are more vulnerable to ocean acidification than coastal waters.

    Lastly, I used field studies to resolve how bacterioplankton is influenced by environmental changes, and how this leads to seasonal succession of marine bacteria. Using high frequency sampling over three years, we uncovered notable variability both between and within years in several biological features that rapidly changed over short time scales. These included potential phytoplankton-bacteria linkages, substrate uptake rates, and shifts in bacterial community structure. Thus, high resolution time series can provide important insights into the mechanisms controlling microbial communities.

    Overall, this thesis highlights the advantages of combining molecular and traditional oceanographic methodological approaches to study ecosystems at high resolution for improving our understanding of the physiology and ecology of microbial communities and, ultimately, how they influence biogeochemical processes.

  • 295.
    Bunse, Carina
    et al.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lundin, Daniel
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Lindh, Markus V.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Department of Biology, Lund University, SE-22362 Lund, Sweden.
    Sjöstedt, Johanna
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Israelsson, Stina
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Martinez-Garcia, Sandra
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Grupo de Oceanografía Biolóxica-Universidade de Vigo, 36310-Vigo, Pontevedra, Spain.
    Baltar, Federico
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science. Department of Marine Sciences, University of Otago, Dunedin NZ-9054, New Zealand.
    Muthusamy, Saraladevi
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pontiller, Benjamin
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Karlsson, Christofer M.G.
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Legrand, Catherine
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Pinhassi, Jarone
    Linnaeus University, Faculty of Health and Life Sciences, Department of Biology and Environmental Science.
    Seasonality and co-occurrences of free-living Baltic Sea bacterioplanktonManuscript (preprint) (Other academic)
  • 296. Burchard, Hans
    et al.
    Craig, Peter D.
    Gemmrich, Johannes R.
    van Haren, Hans
    Mathieu, Pierre-Philippe
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Smith, W. Alex M. Nimmo
    Prandke, Hartmut
    Rippeth, Tom P.
    Skyllingstad, Eric D.
    Smyth, William D.
    Welsh, David J. S.
    Wijesekera, Hemantha W.
    Observational and numerical modeling methods for quantifying coastal ocean turbulence and mixing2008In: Progress in Oceanography, ISSN 0079-6611, E-ISSN 1873-4472, Vol. 76, no 4, 399-442 p.Article, review/survey (Refereed)
    Abstract [en]

    In this review paper, state-of-the-art observational and numerical modeling methods for small scale turbulence and mixing with applications to coastal oceans are presented in one context. Unresolved dynamics and remaining problems of field observations and numerical simulations are reviewed on the basis of the approach that modern process-oriented studies should be based on both observations and models. First of all, the basic dynamics of surface and bottom boundary layers as well as intermediate stratified regimes including the interaction of turbulence and internal waves are briefly discussed. Then, an overview is given on just established or recently emerging mechanical, acoustic and optical observational techniques. Microstructure shear probes although developed already in the 1970s have only recently become reliable commercial products. Specifically under surface waves turbulence measurements are difficult due to the necessary decomposition of waves and turbulence. The methods to apply Acoustic Doppler Current Profilers (ADCPs) for estimations of Reynolds stresses, turbulence kinetic energy and dissipation rates are under further development. Finally, applications of well-established turbulence resolving particle image velocimetry (PIV) to the dynamics of the bottom boundary layer are presented. As counterpart to the field methods the state-of-the-art in numerical modeling in coastal seas is presented. This includes the application of the Large Eddy Simulation (LES) method to shallow water Langmuir Circulation (LC) and to stratified flow over a topographic obstacle. Furthermore, statistical turbulence closure methods as well as empirical turbulence parameterizations and their applicability to coastal ocean turbulence and mixing are discussed. Specific problems related to the combined wave-current bottom boundary layer are discussed. Finally, two coastal modeling sensitivity studies are presented as applications, a two-dimensional study of upwelling and downwelling and a three-dimensional study for a marginal sea scenario (Baltic Sea). It is concluded that the discussed methods need further refinements specifically to account for the complex dynamics associated with the presence of surface and internal waves. (c) 2008 Elsevier Ltd. All rights reserved.

  • 297. Bäckstrom, M.
    et al.
    Karlsson, S.
    Bäckman, L.
    Folkeson, Lennart
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Management and Assessment.
    Lind, B.
    Mobilisation of heavy metals by deicing salts in a roadside environment2004In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, no 3, 720-732 p.Article in journal (Refereed)
    Abstract [en]

    The seasonal variations of some selected heavy metals (Cd, Cu, Pb and Zn) and principal anions in soil solutions were monitored as a function of distance from the road at two field sites in Sweden. During the winter, the conductivity, concentrations of dissolved sodium and chloride increased dramatically due to the application of deicing agents (i.e. NaCl). Due to ion exchange, the pH decreased one unit in the soil solutions, whereas the concentrations of total organic carbon decreased due to coagulation and/or sorption to stationary solids. The heavy metal concentrations increased during the winter, but through different mechanisms. Cadmium concentrations in the aqueous phase increased as a response to ion exchange, possibly also enhanced by the formation of chloride complexes. Similarly, the concentrations of zinc increased, due to ion exchange, with calcium and protons. The mechanisms of mobilisation for copper and lead were not that clear probably due to association with coagulated or sorbed organic matter in combination with colloid dispersion.

  • 298. Cael, B. B.
    et al.
    Seekell, David A.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The size-distribution of Earth's lakes2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, 29633Article in journal (Refereed)
    Abstract [en]

    Globally, there are millions of small lakes, but a small number of large lakes. Most key ecosystem patterns and processes scale with lake size, thus this asymmetry between area and abundance is a fundamental constraint on broad-scale patterns in lake ecology. Nonetheless, descriptions of lake size-distributions are scarce and empirical distributions are rarely evaluated relative to theoretical predictions. Here we develop expectations for Earth's lake area-distribution based on percolation theory and evaluate these expectations with data from a global lake census. Lake surface areas >= 8.5 km(2) are power-law distributed with a tail exponent (T = 1.97) and fractal dimension (d = 1.38), similar to theoretical expectations (T = 2.05; d = 4/3). Lakes <8.5 km(2) are not power-law distributed. An independently developed regional lake census exhibits a similar transition and consistency with theoretical predictions. Small lakes deviate from the power-law distribution because smaller lakes are more susceptible to dynamical change and topographic behavior at sub-kilometer scales is not self-similar. Our results provide a robust characterization and theoretical explanation for the lake size-abundance relationship, and form a fundamental basis for understanding and predicting patterns in lake ecology at broad scales.

  • 299. Cai, Minggang
    et al.
    Hong, Qingquan
    Sun, Jionghui
    Sundqvist, Kristina
    Umeå University, Faculty of Science and Technology, Department of Chemistry.
    Wiberg, Karin
    Umeå University, Faculty of Science and Technology, Department of Chemistry. Department of Aquatic Sciences and Environmental Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Chen, Kai
    Wang, Yun
    Qiu, Cangrong
    Huang, Shuiying
    Concentrations, distribution and sources of polychlorinated dibenzo-p-dioxins and dibenzofurans and dioxin-like polychlorinated biphenyls in coastal sediments from Xiamen, China2016In: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 185, 74-81 p.Article in journal (Refereed)
    Abstract [en]

    Xiamen and its surroundings are representative areas suffering from intense anthropogenic turbulence and contamination in southeast coast of China during rapid industrialization and urbanization period, thus relevant organic pollutants research is necessary to assess the coastal environmental quality and generate management strategy. Contamination status of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and dioxin like polychlorinated biphenyls (DL-PCBs) was investigated for 7 surface sediment samples collected in these areas in January 2007. The given data were used to evaluate the contamination and their potential risks of the pollutants. Concentrations of PCDD/Fs were in the range of 60 to 4089 pg g(-1) (dry weight) with an average of 1706 pg g(-1) and DL-PCBs in the range of 3 to 76 pg g(-1) with an average of 28 pg g(-1). Octa-chlorinated dibenzo-p-dioxin (OCDD) and PCBs 105 and 118 were the main congeners of the PCDD/F and DL-PCB, respectively. The toxicity equivalent concentrations (TEQs) were in the range of 0.15 to 5.2 pg g(-1) (average: 3.0 pg g(-1)) for PCDD/Fs, while in the range of <limit of quantitation (LOQ) to 0.09 pg g(-1) (average: 0.05 pg g(-1)) for DL-PCBs. Congener pattern analysis showed a dominance of OCDD, suggesting main sources were current or historical use of chlorophenol, current use of dioxin contaminated pesticides or atmospheric deposition. Due to the current levels of PCDD/Fs and DL-PCBs in this area, it is necessary to further research their biogeochemical processes and ecological influences in the future.

  • 300.
    Cai, Yongqing
    et al.
    Wuhan Univ Technol, Sch Nav, Wuhan, Peoples R China.; Hubei Key Lab Inland Shipping Technol, Wuhan, Peoples R China.; Natl Engn Res Ctr Water Transport Safety, Wuhan, Peoples R China..
    Wen, Yuanqiao
    Wuhan Univ Technol, Sch Nav, Wuhan, Peoples R China.; Hubei Key Lab Inland Shipping Technol, Wuhan, Peoples R China.; Natl Engn Res Ctr Water Transport Safety, Wuhan, Peoples R China..
    Wu, Lichuan
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Zhou, Chunhui
    Wuhan Univ Technol, Sch Nav, Wuhan, Peoples R China.; Hubei Key Lab Inland Shipping Technol, Wuhan, Peoples R China.; Natl Engn Res Ctr Water Transport Safety, Wuhan, Peoples R China..
    Zhang, Fang
    Wuhan Univ Technol, Sch Nav, Wuhan, Peoples R China.; Hubei Key Lab Inland Shipping Technol, Wuhan, Peoples R China.; Natl Engn Res Ctr Water Transport Safety, Wuhan, Peoples R China..
    Impact of wave breaking on upper-ocean turbulence2017In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 122, no 2, 1513-1528 p.Article in journal (Refereed)
    Abstract [en]

    Previous studies have demonstrated that surface wave breaking can impact upper-ocean turbulence through wave-breaking-induced turbulence kinetic energy (TKE) flux and momentum flux. Wave-breaking-induced momentum flux decays approximately exponentially with depth, and the decay exponent depends on both the wind speed and wave age. With increasing wave age, the decay speed of wave-breaking-induced momentum flux first decreases, reaching a minimum around a wave age of 16, and then increases. In this study, a wave-breaking-induced momentum flux parameterization was proposed based on wave age and wind-speed dependence. The new proposed parameterization was introduced into a one-dimensional (1-D) ocean model along with a wave-age-dependent wave-breaking-induced TKE flux parameterization. The simulation results showed that the wave-breaking impact on the ocean mainly affected the upper-ocean layer. Adding the wave-age impact to the wave-breaking-induced TKE flux and momentum flux improved the 1-D model performance concerning the sea temperature. Moreover, the wave-breaking-induced momentum flux had a larger impact on the simulation results than the wave-breaking-induced TKE flux.

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