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  • 301.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Information relevance for scenarios of Arctic climate and water change2013Konferansepaper (Fagfellevurdert)
    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. 

  • 302.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Relevance of hydro-climatic change projection and monitoring for  assessment of water cycle changes in the Arctic2011Konferansepaper (Fagfellevurdert)
    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.

  • 303.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Spatial patterns of decline in pan-arctic hydrological monitoring networks: a vulnerability map2008Inngår i: Northern Hydrology and its Global Role: XXV Nordic Hydrological Conference, 2008, s. 60-66Konferansepaper (Fagfellevurdert)
    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.

  • 304.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hannerz, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Current status of Pan-Arctic hydrologic and hydrochemical observing networks2007Inngår i: Proceedings from the Arctic Coastal Zones at Risk workshop in Tromsö, Norway, 1-3 October 2007, 2007Konferansepaper (Annet vitenskapelig)
    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.

  • 305.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hannerz, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Pan-Arctic drainage basin monitoring: current status and potential significance for assessment of climate change effects and feedbacks2007Inngår i: Proceedings of the Third International Conference on Climate & Water, 2007, s. 88-93Konferansepaper (Annet vitenskapelig)
    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.

  • 306.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hannerz, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Pan-Arctic Drainage Basin Monitoring: Current Status and Potential Significance for Assessment of Climate Change Impacts and Feedbacks2007Inngår i: Arctic Forum Abstract Volume, 2007Konferansepaper (Annet vitenskapelig)
    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.

  • 307.
    Bring, Arvid
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hannerz, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Pan-Arctic drainage basin observation networks: current status and potential significance for assessment of climate change effects and feedbacks2007Inngår i: 1st IPY workshop on Sustaining Arctic Observing Networks, 2007Konferansepaper (Annet vitenskapelig)
    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.

  • 308.
    Bringfelt, Björn
    SMHI.
    An evapotranspiration model using SYNOP weather observations in the Penman-Monteith equation1998Rapport (Annet vitenskapelig)
    Abstract [en]

    This work was initiated in order to improve the evapotranspiration data used in the HBV model. Evapotranspiration is calculated consecutively by the Penman-Monteith equation using three-hourly SYNOP observations transformed to values of net radiation, water vapour deficit and data necessary for evaluating aerodynamical resistance and surf ace resistance. Transpiration, rainfall interception and a simple treatment of winter evaporation are included. Soil moisture is used for calculating the surface resistance and it is updated three-hourly with the soil moisture accounting routine of the HBV model regarding the contributions from rainfall and snow melt. Then soil moisture is reduced due to total evapotranspiration.

    Two main parts have been developed and are described here:1. A program for interpolation of missing SYNOP observations and2. The evapotranspiration model.Evapotranspiration is calculated for six SYNOP stations used in the HBV model. Using literature parameter values for open land and forest, the calculated transpiration, interception evaporation and snow evaporation are found to assign reasonable values. Only limited tests against measured evapotranspiration have been made, such as some comparisons with winter data from the NOPEX main site in Norunda north of Uppsala. A comparison is made with evapotranspiration data obtained from calibrations of the HBV model. The performance of the evaporation values in the HBV model remains to be tested. 

  • 309.
    Brodeau, Laurent
    et al.
    LEGI, France.
    Barnier, B.
    Treguier, A. -M
    Penduff, T
    Gulev, S.
    An ERA40-based atmospheric forcing for global ocean circulation models2010Inngår i: Ocean Modelling, ISSN 1463-5003, E-ISSN 1463-5011, Vol. 31, nr 3-4, s. 88-104Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 310.
    Brodeau, Laurent
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Koenigk, Torben
    Extinction of the northern oceanic deep convection in an ensemble of climate model simulations of the 20th and 21st centuries2016Inngår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 9, s. 2863-2882Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 311.
    Broman, Barry
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hammarklint, Thomas
    Rannat, Kalev
    Soomere, Tarmo
    Valdmann, Ain
    Trends and extremes of wave fields in the north-eastern part of the Baltic Proper2006Inngår i: Oceanologia, ISSN 0078-3234, Vol. 48, s. 165-184Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 312. Bruen, M.
    et al.
    Krahe, P.
    Zappa, M.
    Olsson, Jonas
    SMHI, Forskningsavdelningen, Hydrologi.
    Vehvilainen, B.
    Kok, K.
    Daamen, K.
    Visualizing flood forecasting uncertainty: some current European EPS platforms-COST731 working group 32010Inngår i: Atmospheric Science Letters, ISSN 1530-261X, E-ISSN 1530-261X, Vol. 11, nr 2, s. 92-99Artikkel i tidsskrift (Fagfellevurdert)
    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

  • 313.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. Univ Zurich, Dept Geog, Zurich, Switzerland..
    Flood type specific construction of synthetic design hydrographs2017Inngår i: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 53, nr 2, s. 1390-1406Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 314.
    Brunner, Manuela Irene
    et al.
    Univ Zurich, Dept Geog, Zurich, Switzerland.;Univ Grenoble Alpes, ENSE, G INP, LTHE, Grenoble, France..
    Seibert, Jan
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära. 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 estimation2016Inngår i: Wine Economics and Policy, ISSN 1934-5070, E-ISSN 2049-1948, Vol. 3, nr 6, s. 819-833Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 315.
    Bryhn, Andreas C.
    et al.
    Swedish Univ Agr Sci, Dept Aquat Resources, Skolgatan 6, SE-74242 Oregrund, Sweden..
    Dimberg, Peter H.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    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 bodies2017Inngår i: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 114, nr 2, s. 664-670Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 316.
    Bryhn, Andreas Christoffer
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Trends in Total Phosphorus Loadings and Concentrations Regarding Surface Waters of the Baltic Sea, 1968-20072010Inngår i: The Open Oceanography Journal, ISSN 1874-2521, Vol. 4, s. 1-8Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 317.
    Brüchert, Volker
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologi och geokemi.
    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 shelf2009Inngår i: Progress in Oceanography, ISSN 0079-6611, E-ISSN 1873-4472, Vol. 83, nr 1-4, s. 169-179Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 318.
    Buapet, Pimchanok
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik. Prince Songkla University, Thailand.
    Gullström, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Björk, Mats
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    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 embayment2013Inngår i: Marine and Freshwater Research, ISSN 1323-1650, E-ISSN 1448-6059, Vol. 64, nr 11, s. 1040-1048Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 319. 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 effective2013Inngår i: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 13, s. 3013-3030Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 320. Buffam, Ishi
    et al.
    Laudon, Hjalmar
    Temnerud, Johan
    Örebro universitet, Institutionen för naturvetenskap.
    Morth, Carl-Magnus
    Bishop, Kevin
    Landscape-scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network2007Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, nr G1, s. G01022-Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 321. Bulbul, A.
    et al.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Huq, S.M.I.
    Gunaratna, K.R.
    Arsenic uptake by fresh water green alga, Chlamydomonas2008Inngår i: 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, s. 389-396Kapittel i bok, del av antologi (Fagfellevurdert)
  • 322.
    Bundschuh, Jochen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630).
    Bhattacharya, ProsunKTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik (flyttat 20130630), Miljögeokemi och ekoteknik.Chandrashekharam, D.
    Natural Arsenic in Groundwater: Occurrence, Remediation and Management2005Collection/Antologi (Fagfellevurdert)
  • 323.
    Bundschuh, Jochen
    et al.
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik.
    Bhattacharya, Prosun
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    von Brömssen, Mattias
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Jakariya, Md
    Jacks, Gunnar
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljögeokemi och ekoteknik.
    Thunvik, Roger
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    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?2009Inngår i: Natural Arsenic in Groundwater of Latin America: Occurrence, health impact and remediation, The Netherlands: CRC Press/Balkema , 2009, s. 677-685Kapittel i bok, del av antologi (Fagfellevurdert)
  • 324.
    Bunse, Carina
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Bacterioplankton in the light of seasonality and environmental drivers2017Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • 325.
    Bunse, Carina
    Linnéuniversitetet, Institutionen för biologi och miljö (BOM).
    Bacterioplankton in the light of seasonality and environmental drivers2017Doktoravhandling, med artikler (Annet vitenskapelig)
    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.

  • 326.
    Bunse, Carina
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Lundin, Daniel
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Lindh, Markus V.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Lund University.
    Sjöstedt, Johanna
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Israelsson, Stina
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Martínez-García, Sandra
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Universidade de Vigo, Spain.
    Baltar, Federico
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). University of Otago, New Zealand.
    Muthusamy, Sarala Devi
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Pontiller, Benjamin
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Karlsson, Christofer M. G.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Legrand, Catherine
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Pinhassi, Jarone
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Seasonality and co-occurrences of free-living Baltic Sea bacterioplanktonManuskript (preprint) (Annet vitenskapelig)
  • 327. Burchard, Hans
    et al.
    Craig, Peter D.
    Gemmrich, Johannes R.
    van Haren, Hans
    Mathieu, Pierre-Philippe
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    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 mixing2008Inngår i: Progress in Oceanography, ISSN 0079-6611, E-ISSN 1873-4472, Vol. 76, nr 4, s. 399-442Artikkel, forskningsoversikt (Fagfellevurdert)
    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.

  • 328. Bäckstrom, M.
    et al.
    Karlsson, S.
    Bäckman, L.
    Folkeson, Lennart
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Miljöbedömning och -förvaltning.
    Lind, B.
    Mobilisation of heavy metals by deicing salts in a roadside environment2004Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 38, nr 3, s. 720-732Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 329. Cael, B. B.
    et al.
    Seekell, David A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    The size-distribution of Earth's lakes2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikkel-id 29633Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 330. Cai, Minggang
    et al.
    Hong, Qingquan
    Sun, Jionghui
    Sundqvist, Kristina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Wiberg, Karin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. 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, China2016Inngår i: Marine Chemistry, ISSN 0304-4203, E-ISSN 1872-7581, Vol. 185, s. 74-81Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 331.
    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 universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    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 turbulence2017Inngår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 122, nr 2, s. 1513-1528Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 332.
    Campagne, Antoine
    et al.
    LEGI, Université Grenoble Alpes.
    Alfredsson, Henrik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Chassagne, Rémi
    LEGI, Université Grenoble Alpes.
    Micard, Diane
    LMFA, École Centrale de Lyon.
    Mordant, Nicolas
    LEGI, Université Grenoble Alpes.
    Segalini, Antonio
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Sommeria, Joel
    LEGI, Université Grenoble Alpes.
    Viboud, Samuel
    LEGI, Université Grenoble Alpes.
    Mohanan, Ashwin Vishnu
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Lindborg, Erik
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Mekanik.
    Augier, Pierre
    LEGI, Université Grenoble Alpes.
    First report of the MILESTONE experiment: strongly stratified turbulence and mixing efficiency in the Coriolis platform2016Inngår i: VIIIth International Symposium on Stratified Flows (ISSF), 2016, 2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Strongly stratified turbulence is a possible interpretation of oceanic and atmospheric mea-surements. However, this regime has never been produced in a laboratory experiment be-cause of the two conditions of very small horizontal Froude number Fh and large buoyancy Reynolds number R which require a verily large experimental facility. We present a new attempt to study strongly stratified turbulence experimentally in the Coriolis platform.The flow is forced by a slow periodic movement of an array of six vertical cylinders of 25 cm diameter with a mesh of 75 cm. Five cameras are used for 3D-2C scanned horizontalparticles image velocimetry (PIV) and stereo 2D vertical PIV. Five density-temperatureprobes are used to measure vertical and horizontal profiles and signals at fixed positions.The first preliminary results indicate that we manage to produce strongly stratified tur-bulence at very small Fh and large R in a laboratory experiment.

  • 333. Campedel, M.
    et al.
    Antonioni, G.
    Cozzani, V.
    Di Baldassarre, Giuliano
    Martorell, S
    Soares, C G
    Barnett, J
    A framework for the assessment of the industrial risk caused by floods2009Inngår i: Safety, reliability and risk analysis: theory, methods and applications / [ed] Sebastián Martorell, C Guedes Soares & Julie Barnett, Dr., 2009, s. 2749-2756Konferansepaper (Fagfellevurdert)
  • 334.
    Carlberg, Stig
    SMHI, Forskningsavdelningen, Oceanografi.
    Conservation of marine ecological quality - a current European perspective2005Inngår i: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 15, nr 3, s. 211-214Artikkel i tidsskrift (Annet vitenskapelig)
  • 335.
    Carlsson, Bengt
    SMHI, Forskningsavdelningen, Hydrologi.
    Alkalinitets- och pH-förändringar i Ume-älven orsakade av minimitappning1993Rapport (Annet vitenskapelig)
    Abstract [sv]

    Med beräknat idrifttagande 1994 bygger Vattenfall f n en kraftstation vid Klippen i Umeälven söder om Överurnan. I samband med idrifttagandet kommer vattenföringen på en knappt 10 km lång älvsträcka mellan Umeälvens utlopp ur Överurnan och Klippen att minskas. Ingreppet kommer att medföra en minskning av alkalinitet och pH-värdena på älvsträckan ifråga. För att i möjligaste mån lindra konsekvenserna har en minimitappning på 2,0 m3/s från 1 juni till 15 september och 0,5 m3 /s under resten av året, föreslagits. Modellsimuleringar av pH och alk:alinitet har skett för tiden 1984-91. Resultaten visar att alk:aliniteten minskar från årslägsta värden på 0,05 - 0,06 mekv/1 till 0,02 - 0,03 mekv/1, vilket motsvarar en sänkning av pH från 6,6 - 6,7 till 6,2 - 6,3.

  • 336.
    Carlsson, Bengt
    SMHI, Forskningsavdelningen, Hydrologi.
    Hydrokemiska data från de svenska fältforskningsområdena1985Rapport (Annet vitenskapelig)
    Abstract [sv]

    En viktig uppgift för SMHI är att övervaka och fortlöpande geupplysningar om hydrologiska data i Sverige. I och med övertagandet1979 av ansvaret för de av NFR upprättade FältForsknings~mrådena (FFO) har även hydrokemin kommit att utgöra ennaturlig del av SMHis verksamhetsområde.Denna rapport utgör en första publicering av de hydrokemiskadata med korresponderande vattenföringsdata, som idag, 1985,finns på SMHI i FFO-arkivet. Materialet presenteras här iform av tidsdiagram samt en tabell över de analyserade variablernasmedelvärden. Ytterligare en del äldre material frånIHD-områden finns fortfarande utspritt på andra institutionermen skall så småningom läggas in i FFO-arkivet. Rapporteninnehåller också en kortfattad beskrivning av varje område.Inga försök till utvärdering har gjorts. Dock har observeratsen viss skillnad i haltnivå för bl a Cl och N0 2 från IHDperioden1965-75 (analyserade av MISU) jämfört med perioden1979-84 (analyserade av SMHI). Orsaken skall utredas. Avsiktenär att på ett överskådligt sätt redovisa vilka data, somfinns tillgängliga för forskningsändamål.

  • 337.
    Carlsson, Bengt
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Sanner, Håkan
    SMHI, Samhälle och säkerhet.
    Influence of river regulation on runoff to the Gulf of Bothnia: Gulf of Bothnia Year 19911994Rapport (Annet vitenskapelig)
  • 338.
    Carlsson, Bengt
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Sanner, Håkan
    SMHI.
    Modelling influence of river regulation on runoff to the Gulf of Bothnia1996Inngår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 27, nr 5, s. 337-350Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Runoff from a land area of approximately 490,000 km(2) enters the Gulf of Bothnia. This runoff is of essential importance for the flushing of the Gulf. a change in the volume of runoff effects the residence time. There are many natural as well as man made changes in the runoff, both in the form of long-term changes over many years and those occurring within one year. The most significant man made changes come from hydropower regulation. This report describes the effect on runoff from the development of the hydropower plants in Sweden and Finland by means of comparing recorded regulated runoff and simulated natural runoff. A recent time period, 1980-91, and a time period before regulation, 1925-36, were simulated. The monthly magnitudes of the redistributed flows were found to be on average 1,700 m(3)/s. The maximum redistributed monthly flow in May - June reached 5,000-6,000 m(3)/s.

  • 339.
    Carlsson, Björn
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Papadimitrakis, Yiannis
    Water Resources and Environmental Engineering Div., School of Civil Engineering, National Technical University of Athens, Greece.
    Rutgersson, Anna
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Geovetenskapliga sektionen, Institutionen för geovetenskaper, Luft-, vatten och landskapslära.
    Evaluation of a roughness length model and sea surface properties with data from the Baltic Sea2010Inngår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 40, nr 9, s. 2007-2024Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The exchange of momentum between the oceans and atmosphere is important for many atmospheric and oceanic processes and is mainly governed by the roughness of sea surface. The roughness can be expressed by a roughness length z0. A roughness length model, based on the concept that z0 is determined by stochastic wave breaking, is presented. The model performance is evaluated using measurements from the Östergarnsholm site, in the Baltic Sea, and pertinent information from other recent investigations. The wave field and the roughness length variations are investigated during various sea state conditions dominated by wind-driven waves. It is found that several parameters, describing the characteristics of the wave field, are dependent on the amount of energy that long waves have relative to the energy of short, wind-driven waves of the sea spectrum (called the swell ratio). The impact of swell ratio on z0 can explain the discrepancies found in various results among relevant investigations. The roughness length model can well reproduce the observed roughness length.

  • 340.
    Carlund, Thomas
    et al.
    SMHI, Samhälle och säkerhet.
    Håkansson, Bertil
    SMHI, Forskningsavdelningen, Oceanografi.
    Land, P
    Aerosol optical depth over the Baltic Sea derived from AERONET and SeaWiFS measurements2005Inngår i: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 26, nr 2, s. 233-245Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Three years of data on aerosol optical depth (tau(a)) from the Aerosol Robotic Network (AERONET) station on the island of Gotland in the Baltic Sea have been analysed and compared with Sea-viewing Wide Field of view Sensor (SeaWiFS) data. Normally, the atmosphere over Gotland could be considered as clear, with a daily median value Of tau(a) at 500 nm of about 0.08. The median value of Angstrom's wavelength exponent (alpha) for wavelengths between 440 nm and 870 nm was 1.37, indicating that the dominant aerosol is more of a continental than of a pure maritime type. SeaWiFS GAC level 2 data on tau(a) and alpha were compared to data from the ground-based AERONET station. For the 37 cases of simultaneous satellite and ground-based measurements under cloud-free skies it was found that, on average, the value of tau(a)(865 nm) from SeaWiFS was about 0.02 higher than tau(a)(870 nm) from the AERONET station. At the same time approximate tau(a)(440 nm) from SeaWiFS was about 0.03 lower than tau(a)(440 nm) of AERONET. alpha(510, 865) from SeaWiFS was, on average, 1.2 lower than alpha(500, 870) from the AERONET measurements. These results cannot explain the very frequent occurences of negative values of normalized water-leaving radiance at 412 nm and 443 nm in the SeaWiFS reprocessing #3 data.

  • 341.
    Carney Almroth, Bethanie M.
    et al.
    University of Gothenburg.
    Åström, Linn
    University of Gothenburg.
    Roslund, Sofia
    Petersson, Hanna
    Johansson, Mats
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Persson, Nils-Krister
    Högskolan i Borås, Akademin för textil, teknik och ekonomi.
    Quantifying shedding of synthetic fibers from textiles; a source ofmicroplastics released into the environment2017Inngår i: Environmental science and pollution research international, ISSN 0944-1344, E-ISSN 1614-7499, artikkel-id 10.1007/s11356-017-0528-7Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Microplastics in the environment are a subject of intense research as they pose a potential threat to marine organisms. Plastic fibers from textiles have been indicated as a major source of this type of contaminant, entering the oceans via wastewater and diverse non-point sources. Their presence is also documented in terrestrial samples. In this study, the amount of microfibers shedding from synthetic textiles was measured for three materials (acrylic, nylon, polyester), knit using different gauges and techniques. All textiles were found to shed, but polyester fleece fabrics shed the greatest amounts, averaging 7360 fibers/m−2/L−1 in one wash, compared with polyester fabrics which shed 87 fibers/m−2/L−1. We found that loose textile constructions shed more, as did worn fabrics, and high twist yarns are to be preferred for shed reduction. Since fiber from clothing is a potentially important source of microplastics, we suggest that smarter textile construction, prewashing and vacuum exhaustion at production sites, and use of more efficient filters in household washing machines could help mitigate this problem.

  • 342.
    Carpman, Nicole
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Marine Current Resource Assessment: Measurements and Characterization2015Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The increasing interest in converting energy from renewable resources into electricity has led to an increase in research covering the field of marine current energy, mainly concerning tidal currents and in-stream tidal turbines. Tides have the advantage of being predictable decades ahead. However, the tidal resource is intermittent and experiences local variations that affect the power output from a conversion system. The variability is mainly due to four aspects: the tidal regime, the tidal cycle, bathymetry at the site and weather effects. Each potential site is unique, the velocity flow field at tidal sites is highly influenced by local bathymetry and turbulence. Hence, characterizing the resource requires careful investigations and providing high quality velocity data from measurement surveys is of great importance. In this thesis, measurements of flow velocities have been performed at three kinds of sites.

    A tidal site has been investigated for its resource potential in one of all of the numerous fjords in Norway. Measurements have been performed to map the spatial and temporal variability of the resource. Results show that currents in the order of 2 m/s are present in the center of the channel. Furthermore, the flow is highly bi-directional between ebb and flood flows. The site thus have potential for in-stream energy conversion. A model is proposed that predicts peak current speed from information on tidal range at the site. A corresponding model can be set up and implemented at other similar sites affected by tides, i.e. fjord inlets connecting the ocean to a fjord or a basin.

    A river site serves as an experimental site for a marine current energy converter that has been designed at Uppsala University and deployed in Dalälven, Söderfors. The flow rate at the site is regulated by an upstream hydrokinetic power plant nearby, making the site suitable for experiments on the performance of the vertical axis turbine in its natural environment. The turbine has been run in uniform flow and measurements have been performed to characterize the extent of the wake.

    An ocean current site was a target of investigation for its potential for providing utilizable renewable energy. A measurement campaign was conducted, mapping the flow both spatially and temporally. However, the site was shown to not be suitable for energy conversion using present technique.

  • 343.
    Carpman, Nicole
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Thomas, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Tidal current phasing along the coast of Norway2016Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Tidal currents provide an intermittent source of renewable energy. A high degree of intermittency is unfavorable in the existing power system. However, by aggregating tidal power from sites with variable tidal phase a more firm power outpu tmay be achieved. In this paper, the tidal current phasing between 114 potential tidal energy sites along the Norwegian coast is investigated. Time series of tidal currents are generated with a model that considers the variation in current strength due to the variability in the semi-diurnal tidal cycle (spring to neap, flood to ebb, first to second daily tide etc.). From these, available kinetic energy in the natural flow is calculated. A constant conversion rate is then applied to give the power output at each site. Three scenarios, with varying number of sites and energy extraction, are investigated. The variability in each scenario is quantified on different time scales by filtering the aggregated power and calculate standard deviation and step change. It is found that the variability can be lowered by choosing sites with an advantageous time lag and limit the power output from the most energetic sites. As expected, smoothing is most distinct on short time scales.

  • 344.
    Carpman, Nicole
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Thomas, Karin
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för teknikvetenskaper, Elektricitetslära.
    Tidal resource characterization in the Folda Fjord, Norway2016Inngår i: International Journal of Marine Energy, ISSN 2214-1669, Vol. 13, s. 27-44Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    For tidal-stream energy industry to be fully realized, lower velocity sites and fjords should be developed. Finding new prospective sites for in-stream energy extraction from tidal currents is an area of ongoing research. In this paper, the tidal flow at a fjord inlet has been characterized using acoustic Doppler current profiler (ADCP) measurements. This work is based on two survey measurement techniques: transect measurements to map the spatial variability, and seabed measurements to map the temporal variability. The data was analyzed in terms of characterizing metrics, to ensure they are comparable with other resource assessments. Results show that currents exceed 1 m/s for 38% of the time with peak currents of 2.06 m/s at hub height (middle of the water column) and the directional asymmetry is less than 1° between ebb and flood, indicating a truly bi-directional flow. A simple prediction model is proposed which allows peak current speeds to be accurately predicted in the channel center from tidal range data using a linear relationship. The relationship is shown to be strong, with a correlation coefficient of 0.98 at hub height, and a standard variation typically less than 10 cm/s. Furthermore, it is show that a minimum of 9 days of measurements are required to set up the model, although it takes 29 days to reduce the error in peak speed to less than 1%. However, the error is expected to vary depending on where in the monthly tidal cycle the survey begins, it is thus recommended to measure around spring tide if the measurement period is short.

  • 345. Carstens, C.
    et al.
    Cvetkovic, V.
    Destouni, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Groundwater flow partitioning in near-coastal catchments of central Scandinavia2011Inngår i: Geophysical Research Abstracts,  Vol. 13, EGU2011-7880, 2011Konferansepaper (Fagfellevurdert)
  • 346.
    Carstens, Christoffer
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Mark- och vattenteknik, Vattenvårdsteknik.
    In the Pipe or End of Pipe?: Transport and Dispersion of Water-borne Pollutants and Feasibility of Abatement Measures2012Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Eutrophication is one of the key environmental problems of today, both in terms of complexity and magnitude. For the Baltic Sea (BS), eutrophication is an acute problem, leading to hypoxic conditions at the bottom; a situation that is sustained and amplified, when phosphorus is released from hypoxic sediments. Reducing nutrient loading is a top political priority but the present situation is believed to require active measures within the catchments and recipients to reduce both loading and adverse effects. Implementation of effective and cost-efficient abatement methods requires understanding of natural processes in watersheds, streams and recipients as well as technological expertise in order to compare the effects of measures of different kinds and locations. This thesis tries to combine process understanding of catchment transport behaviour, especially in coastal zones, and feasibility of certain technologies for reducing nutrient loading and effects of eutrophication in-situ. The over-arching theme is the fate of the individual contaminant, from injection to removal. Transport and dispersion in catchments are investigated, combining physically-based, distributed, numerical groundwater models with Lagrangian stochastic advective reactive solute (LaSAR) transport modelling. The approach is powerful in the sense that it incorporates catchment structural, geomorphological dispersion in the numerical model with hydrodynamic and sub-scale dispersion as well as uncertainty in the LaSAR framework. The study exemplifies the complex nature of transport time distributions in catchments in general and when varying source size and location, importance of dispersion parameters and retention due to molecular diffusion. It is shown that geomorphological control on dispersion is present even for relatively heterogeneous systems and that neither the mean residence time nor a statistical distribution may provide accurate representations of hydrological systems. To combat internal loading of P from sediments in-situ, large-scale aeration of deep waters, halocline ventilation, has been suggested. This study further investigates the feasibility of wave-powered devices to meet the energy demands for such an operation. It is shown that the required amount of oxygen needed to keep the sediments at oxic conditions could be provided, cheaply and efficiently, through the use of wave power.

  • 347.
    Casas-Ruiz, Joan P.
    et al.
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain..
    Tittel, Joerg
    UFZ Helmholtz Ctr Environm Res, Dept Lake Res, Bruckstr 3a, D-39114 Magdeburg, Germany..
    von Schiller, Daniel
    Univ Basque Country, Fac Sci & Technol, Dept Plant Biol & Ecol, Apdo 644, Bilbao 48080, Spain..
    Catalan, Nuria
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi.
    Obrador, Biel
    Univ Barcelona, Dept Ecol, Av Diagonal 643, E-08028 Barcelona, Spain..
    Gomez-Gener, Lluis
    Univ Barcelona, Dept Ecol, Av Diagonal 643, E-08028 Barcelona, Spain..
    Zwirnmann, Elke
    Leibniz Inst Freshwater Ecol & Inland Fisheries, Muggelseedamm 301, D-12587 Berlin, Germany..
    Sabater, Sergi
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain.;Univ Girona, Inst Aquat Ecol, Girona 17071, Spain..
    Marce, Rafael
    Catalan Inst Water Res ICRA, Emili Grahit 101, Girona 17003, Spain..
    Drought-induced discontinuities in the source and degradation of dissolved organic matter in a Mediterranean river2016Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 127, nr 1, s. 125-139Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The composition of dissolved organic matter (DOM) in rivers results from the different sources and in-stream transformations along the land to ocean aquatic continuum. Riverine DOM sources are highly dependent on the hydrological connection between the river channel and the surrounding terrestrial ecosystems, but how the lack of this connectivity (e.g., during drought episodes) affects the sources and biodegradation of DOM in rivers remains unclear. Here we identified the DOM sources as well as the different DOM pools that are respired along a Mediterranean river during drought by combining absorbance-fluorescence spectroscopy, size-exclusion chromatography, biodegradation assays, and stable and radiocarbon isotopes. DOM composition was highly heterogeneous along the river in response to different sources and in-stream processes in each distinct aquatic environment (i.e., isolated water pools, running waters, and impounded waters in weirs). The reduced hydrological connectivity with terrestrial ecosystems promoted the influence of autochthonous DOM sources. Still, tree leaves from overhanging canopies stood out as an important terrestrial DOM source, especially in sites where water residence time was high such as isolated pools and weirs. Degradation of leaf leachates was a relevant process in these sites, whereas autochthonous DOM and groundwater millennial DOM (> 1300 year B.P.) seemed to be degraded in running waters. Overall, our results highlight that the drought-induced hydrological disconnection entails a great spatial heterogeneity in the sources of DOM, which at the same time determines the different DOM pools that are respired in each environment along the river.

  • 348. Casini, Michele
    et al.
    Kall, Filip
    Hansson, Martin
    SMHI, Samhälle och säkerhet.
    Plikshs, Maris
    Baranova, Tatjana
    Karlsson, Olle
    Lundstrom, Karl
    Neuenfeldt, Stefan
    Gardmark, Anna
    Hjelm, Joakim
    Hypoxic areas, density-dependence and food limitation drive the body condition of a heavily exploited marine fish predator2016Inngår i: Royal Society Open Science, E-ISSN 2054-5703, Vol. 3, nr 10, artikkel-id 160416Artikkel i tidsskrift (Fagfellevurdert)
  • 349.
    Cassidy, Lynn
    et al.
    University of Botswana.
    Wilk, Julie
    Linköpings universitet, Institutionen för tema, Centrum för klimatpolitisk forskning. Linköpings universitet, Institutionen för tema, Tema vatten i natur och samhälle. Linköpings universitet, Filosofiska fakulteten.
    Kgathi, Donald
    University of Botswana.
    Bendsen, Hannelore
    University of Botswana.
    Ngwenya, Barbara
    University of Botswana.
    Indigenous Knowledge, Livelihoods and Government Policy2011Inngår i: Rural Livelihoods, Risk and Political Economy of Access to Natural Resources in the Okavango Delta, Botswana / [ed] Kgathi, D.L., Ngwenya, B.N. and Darkoh, M.K.B., Nova Publishers , 2011Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    The Okavango Delta, a globally renowned wetland, is characterized by a mosaic of meandering watercourses, floodplains and islands, and is home to a variety of wildlife and vegetation species. It is a major source of livelihoods for the local communities and also an important attraction for tourism, the second most important economic activity in Botswana after diamonds, contributing 5% to the gross domestic product (GDP). As a globally renowned Ramsar Site and major tourist attraction, the Okavango Delta is a resource of national, regional and international importance. This book examines the results of empirical micro-level studies undertaken in the Okavango Delta and contributes to the formulation of relevant policies for sustainable development in the Okavango Delta. (Imprint: Nova Press)

  • 350. CASTELLARIN, A
    et al.
    Di Baldassarre, Giuliano
    Postdoctoral Researcher, School of Civil Engineering, Dept. DISTART, Univ. of Bologna, Bologna 40136, Italy .
    BATES, PD
    BRATH, A
    Optimal Cross-Sectional Spacing in Preissmann Scheme 1D Hydrodynamic Models2009Inngår i: Journal of Hydraulic Engineering, ISSN 0733-9429, E-ISSN 1943-7900, Vol. 135, nr 2, s. 96-105Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Choosing a suitable set of cross sections for the representation of the natural geometry of a river is important for the efficiency of one-dimensional (1D) hydraulic models, but only few guidelines are available for the selection of the most suitable distance between cross sections, depending on the hydraulic problem at hand. This issue is investigated by examining models of a ∼55km reach of the River Po, Italy, and a ∼16km reach of the River Severn, United Kingdom, for both of which high quality laser scanning altimetry are available. The high-resolution digital terrain models of the two river reaches enabled the construction of a series of hypothetical topographical ground surveys with different spacing between cross sections, which could be used as input to a standard 1D model (UNET). Both historical and synthetic flood events for the two river reaches were simulated, and the results were then analyzed to quantify the accuracy associated with each resolution and to assess how survey resolution impacts the performance of standard 1D models. The study results agree with the available suggestions in the literature and provide useful guidelines for 1D hydrodynamic modeling.

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