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  • 451.
    Andersson, Jafet
    et al.
    SMHI, Research Department, Hydrology.
    Pechlivanidis, Ilias
    SMHI, Research Department, Hydrology.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Key factors for improving large-scale hydrological model performance2015In: European Water, ISSN 1792-085X, Vol. 49, p. 77-88Article in journal (Refereed)
  • 452. Groger, Matthias
    et al.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Thermal air-sea coupling in hindcast simulations for the North Sea and Baltic Sea on the NW European shelf2015In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 26911Article in journal (Refereed)
    Abstract [en]

    This article compares interactively coupled atmosphere-ocean hindcast simulations with stand-alone runs of the atmosphere and ocean models using the recently developed regional ocean-atmosphere model NEMO-Nordic for the North Sea and Baltic Sea. In the interactively coupled run, the ocean and the atmosphere components were allowed to exchange mass, momentum and heat every 3 h. Our results show that interactive coupling significantly improves simulated winter sea surface temperatures (SSTs) in the Baltic Sea. The ocean and atmosphere stand-alone runs, respectively, resulted in too low sea surface and air temperatures over the Baltic Sea. These two runs suffer from too cold prescribed ERA40 SSTs, which lower air temperatures and weaken winds in the atmosphere only run. In the ocean-only run, the weaker winds additionally lower the vertical mixing thereby lowering the upward transport of warmer subpycnocline waters. By contrast, in the interactively coupled run, the ocean-atmosphere heat exchange evolved freely and demonstrated good skills in reproducing observed surface temperatures. Despite the strong impact on oceanic and atmospheric variables in the coupling area, no far reaching influence on atmospheric variables over land can be identified. In perturbation experiments, the different dynamics of the two coupling techniques is investigated in more detail by implementing strong positive winter temperature anomalies in the ocean model. Here, interactive coupling results in a substantially higher preservation of heat anomalies because the atmosphere also warmed which damped the ocean to atmosphere heat transfer. In the passively coupled set-up, this atmospheric feedback is missing, which resulted in an unrealistically high oceanic heat loss. The main added value of interactive air-sea coupling is twofold: (1) the elimination of any boundary condition at the air-sea interface and (2) the more realistic dynamical response to perturbations in the ocean-atmosphere heat balance, which will be essential in climate warming scenarios.

  • 453. Aich, Valentin
    et al.
    Liersch, Stefan
    Vetter, Tobias
    Andersson, Jafet
    SMHI, Research Department, Hydrology.
    Mueller, Eva N.
    Hattermann, Fred F.
    Climate or Land Use?-Attribution of Changes in River Flooding in the Sahel Zone2015In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 7, no 6, p. 2796-2820Article in journal (Refereed)
    Abstract [en]

    This study intends to contribute to the ongoing discussion on whether land use and land cover changes (LULC) or climate trends have the major influence on the observed increase of flood magnitudes in the Sahel. A simulation-based approach is used for attributing the observed trends to the postulated drivers. For this purpose, the ecohydrological model SWIM (Soil and Water Integrated Model) with a new, dynamic LULC module was set up for the Sahelian part of the Niger River until Niamey, including the main tributaries Sirba and Goroul. The model was driven with observed, reanalyzed climate and LULC data for the years 1950-2009. In order to quantify the shares of influence, one simulation was carried out with constant land cover as of 1950, and one including LULC. As quantitative measure, the gradients of the simulated trends were compared to the observed trend. The modeling studies showed that for the Sirba River only the simulation which included LULC was able to reproduce the observed trend. The simulation without LULC showed a positive trend for flood magnitudes, but underestimated the trend significantly. For the Goroul River and the local flood of the Niger River at Niamey, the simulations were only partly able to reproduce the observed trend. In conclusion, the new LULC module enabled some first quantitative insights into the relative influence of LULC and climatic changes. For the Sirba catchment, the results imply that LULC and climatic changes contribute in roughly equal shares to the observed increase in flooding. For the other parts of the subcatchment, the results are less clear but show, that climatic changes and LULC are drivers for the flood increase; however their shares cannot be quantified. Based on these modeling results, we argue for a two-pillar adaptation strategy to reduce current and future flood risk: Flood mitigation for reducing LULC-induced flood increase, and flood adaptation for a general reduction of flood vulnerability.

  • 454. Thirel, G.
    et al.
    Andreassian, V.
    Perrin, C.
    Audouy, J. -N
    Berthet, L.
    Edwards, P.
    Folton, N.
    Furusho, C.
    Kuentz, A.
    Lerat, J.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Martin, E.
    Mathevet, T.
    Merz, R.
    Parajka, J.
    Ruelland, D.
    Vaze, J.
    Hydrology under change: an evaluation protocol to investigate how hydrological models deal with changing catchments2015In: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 60, no 7-8, p. 1184-1199Article in journal (Refereed)
    Abstract [en]

    Testing hydrological models under changing conditions is essential to evaluate their ability to cope with changing catchments and their suitability for impact studies. With this perspective in mind, a workshop dedicated to this issue was held at the 2013 General Assembly of the International Association of Hydrological Sciences (IAHS) in Goteborg, Sweden, in July 2013, during which the results of a common testing experiment were presented. Prior to the workshop, the participants had been invited to test their own models on a common set of basins showing varying conditions specifically set up for the workshop. All these basins experienced changes, either in physical characteristics (e.g. changes in land cover) or climate conditions (e.g. gradual temperature increase). This article presents the motivations and organization of this experimentthat isthe testing (calibration and evaluation) protocol and the common framework of statistical procedures and graphical tools used to assess the model performances. The basins datasets are also briefly introduced (a detailed description is provided in the associated Supplementary material).

  • 455. Malnes, E.
    et al.
    Buanes, A.
    Nagler, T.
    Bippus, G.
    Gustafsson, David
    SMHI, Research Department, Hydrology.
    Schiller, C.
    Metsamaki, S.
    Pulliainen, J.
    Luojus, K.
    Larsen, H. E.
    Solberg, R.
    Diamandi, A.
    Wiesmann, A.
    User requirements for the snow and land ice services - CryoLand2015In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 9, no 3, p. 1191-1202Article in journal (Refereed)
    Abstract [en]

    CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired.

  • 456. van Vliet, Michelle T. H.
    et al.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Strombäck, Lena
    SMHI, Research Department, Hydrology.
    Capell, Réne
    SMHI, Research Department, Hydrology.
    Ludwig, Fulco
    European scale climate information services for water use sectors2015In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 528, p. 503-513Article in journal (Refereed)
    Abstract [en]

    This study demonstrates a climate information service for pan-European water use sectors that are vulnerable to climate change induced hydrological changes, including risk and safety (disaster preparedness), agriculture, energy (hydropower and cooling water use for thermoelectric power) and environment (water quality). To study the climate change impacts we used two different hydrological models forced with an ensemble of bias-corrected general circulation model (GCM) output for both the lowest (2.6) and highest (8.5) representative concentration pathways (RCP). Selected indicators of water related vulnerability for each sector were then calculated from the hydrological model results. Our results show a distinct north-south divide in terms of climate change impacts; in the south the water availability will reduce while in the north water availability will increase. Across different climate models precipitation and streamflow increase in northern Europe and decrease in southern Europe, but the latitude at which this change occurs varies depending on the GCM. Hydrological extremes are increasing over large parts of Europe. The agricultural sector will be affected by reduced water availability (in the south) and increased drought. Both streamflow and soil moistures droughts are projected to increase in most parts of Europe except in northern Scandinavia and the Alps. The energy sector will be affected by lower hydropower potential in most European countries and reduced cooling water availability due to higher water temperatures and reduced summer river flows. Our results show that in particular in the Mediterranean the pressures are high because of increasing drought which will have large impacts on both the agriculture and energy sectors. In France and Italy this is combined with increased flood hazards. Our results show important impacts of climate change on European water use sectors indicating a clear need for adaptation. (C) 2015 Published by Elsevier B.V.

  • 457.
    Arheimer, Berit
    et al.
    SMHI, Research Department, Hydrology.
    Nilsson, Johanna
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Experimenting with Coupled Hydro-Ecological Models to Explore Measure Plans and Water Quality Goals in a Semi-Enclosed Swedish Bay2015In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 7, no 7, p. 3906-3924Article in journal (Refereed)
    Abstract [en]

    Measure plans are currently being developed for the Water Framework Directive (WFD) by European water authorities. In Sweden, such plans include measures for good ecological status in the coastal ecosystem. However, the effect of suggested measures is not yet known. We therefore experimented with different nutrient reduction measures on land and in the sea, using a model system of two coupled dynamic models for a semi-enclosed bay and its catchment. The science question was whether it is worthwhile to implement measures in the local catchment area to reach local environmental goals, or if the status of the Bay is more governed by the water exchange with the Sea. The results indicate that by combining several measures in the catchment, the nutrient load can be reduced by 15%-20%. To reach the same effect on nutrient concentrations in the Bay, the concentrations of the sea must be reduced by 80%. Hence, in this case, local measures have a stronger impact on coastal water quality. The experiment also show that the present targets for good ecological status set up by the Swedish water authorities may be unrealistic for this Bay. Finally, we discuss when and how to use hydro-ecological models for societal needs.

  • 458.
    Bergström, Sten
    et al.
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Core Services.
    Interpretation of runoff processes in hydrological modelling experience from the HBV approach2015In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 29, no 16, p. 3535-3545Article in journal (Refereed)
    Abstract [en]

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

  • 459.
    Berg, Peter
    et al.
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Model Consistent Pseudo-Observations of Precipitation and Their Use for Bias Correcting Regional Climate Models2015In: CLIMATE, ISSN 2225-1154, Vol. 3, no 1, p. 118-132Article in journal (Refereed)
    Abstract [en]

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

  • 460. Weigel, Benjamin
    et al.
    Andersson, Helén
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Blenckner, Thorsten
    Snickars, Martin
    Bonsdorff, Erik
    Long-term progression and drivers of coastal zoobenthos in a changing system2015In: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 528, p. 141-159Article in journal (Refereed)
    Abstract [en]

    Coastal zones are facing climate-driven change coupled with escalating eutrophication. With increasing shifts in hydrographic conditions during the past few decades, a focal task is to understand how environmental drivers affect zoobenthic communities, which play a crucial role in ecosystem functioning. By using long-term data, spanning 40 yr (1973 to 2013) in the northern Baltic Sea, we showed a disparity in zoobenthic responses with pronounced changes in community composition and a trend towards decreased biomass in sheltered areas, while biomasses increased in exposed areas of the coastal zone. We used generalized additive modeling to show that bottom oxygen saturation, sea surface temperature and organic load of the sediments were the main environmental drivers behind contrasting patterns in biomass progression. Oxygen saturation alone explained over one third of the deviation in the biomass developments in sheltered areas, while exposed areas were mainly limited by organic content of the sediments. We analyzed high-resolution climate-scenario simulations, following the Intergovernmental Panel on Climate Change scenarios for the Baltic Sea region in combination with different nutrient load scenarios, for the end of the 21st century. The scenario outcomes showed negative trends in bottom oxygen concentrations throughout the coastal and archipelago zone along with overall increasing temperatures and primary production, and decreasing salinity. Our results suggest that these projected future conditions will strengthen the observed pattern in decreasing zoobenthic production in the immediate coastal zones. Moreover, the potential intensification of unfavorable conditions ex-panding seaward may lead to an expansion of biomass loss to more exposed sites.

  • 461.
    Kuentz, Anna
    et al.
    SMHI, Core Services.
    Mathevet, T.
    Gailhard, J.
    Hingray, B.
    Building long-term and high spatio-temporal resolution precipitation and air temperature reanalyses by mixing local observations and global atmospheric reanalyses: the ANATEM model2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 6, p. 2717-2736Article in journal (Refereed)
    Abstract [en]

    Efforts to improve the understanding of past climatic or hydrologic variability have received a great deal of attention in various fields of geosciences such as glaciology, dendrochronology, sedimentology and hydrology. Based on different proxies, each research community produces different kinds of climatic or hydrologic reanalyses at different spatio-temporal scales and resolutions. When considering climate or hydrology, many studies have been devoted to characterising variability, trends or breaks using observed time series representing different regions or climates of the world. However, in hydrology, these studies have usually been limited to short temporal scales (mainly a few decades and more rarely a century) because they require observed time series (which suffer from a limited spatio-temporal density). This paper introduces ANATEM, a method that combines local observations and large-scale climatic information (such as the 20CR Reanalysis) to build long-term probabilistic air temperature and precipitation time series with a high spatio-temporal resolution (1 day and a few km(2)). ANATEM was tested on the reconstruction of air temperature and precipitation time series of 22 watersheds situated in the Durance River basin, in the French Alps. Based on a multi-criteria and multi-scale diagnosis, the results show that ANATEM improves the performance of classical statistical models - especially concerning spatial homogeneity - while providing an original representation of uncertainties which are conditioned by atmospheric circulation patterns. The ANATEM model has been also evaluated for the regional scale against independent long-term time series and was able to capture regional low-frequency variability over more than a century (1883-2010).

  • 462. Konigson, Sara J.
    et al.
    Fredriksson, Ronny E.
    Lunneryd, Sven-Gunnar
    Strömberg, Patrik
    SMHI, Core Services.
    Bergstrom, Ulf M.
    Cod pots in a Baltic fishery: are they efficient and what affects their efficiency?2015In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 72, no 5, p. 1545-1554Article in journal (Refereed)
    Abstract [en]

    With the growing grey seal population in the Baltic Sea, the inshore cod fishery has suffered dramatic increases in both catch losses and damage to fishing gear. To mitigate this situation, cod pots were evaluated as an alternative to traditional gillnets and longlines. During a 3-year study, cod pots were used by commercial fishers in two areas off the coast of Sweden. Using the data from this study, we evaluated catches from pots in relation to other gear types and investigated the effects of environmental and fisheries-related variables such as depth and soak time. The comparison of pots with other gear types showed that, during the first half of the year, the pot fishery generated lower daily catches than the gillnet and longline fisheries at comparable fishing efforts. During the second half of the year, catches in the pot fishery exceeded or were equal to those in the traditional fisheries. Using generalized additive models to evaluate the impact of environmental and fisheries-related variables on pot catches, we showed that, in both areas, the catch per unit effort (cpue) of legal-sized cod was affected by the water depth, the time of year (months), and the soak time. In one of the areas, cpue was also affected by the direction of the water current in relation to the orientation of the string of pots. The cpue of undersized cod was affected by topographic variables such as the slope and the complexity of the bottom, in addition to the water depth, month of the year, and soak time. The results from the study indicate that pots can be a useful alternative gear in the Baltic cod fishery, at least during part of the year. By using our information on how catches are affected by environmental and fisheries-related variables, the pot fishery may be further optimized to increase catches.

  • 463. Wilk, Julie
    et al.
    Hjerpe, Mattias
    Yang, Wei
    SMHI, Research Department, Hydrology.
    Fan, Hua
    Farm-scale adaptation under extreme climate and rapid economic transition2015In: Environment, Development and Sustainability, ISSN 1387-585X, E-ISSN 1573-2975, Vol. 17, no 3, p. 393-407Article in journal (Refereed)
    Abstract [en]

    This paper aims to analyse what shapes farmers' vulnerability and adaptation strategies in the context of rapid change. Xinjiang is semi-arid, with extremes of temperature, growing seasons and winds. Favourable socioeconomic conditions have boosted the wellbeing of farmers in the past decades. Interviews with forty-seven farmers led to the categorization of five groups according to the predominant type of farming activity: animal farmers, government farmers (leasing land from the Xinjiang Production and Construction Group), crop farmers, agri-tourism operators and entrepreneurs. High government support has aided farmers to deal with climate challenges, through advanced technology, subsidies and loans. Farmers, however, greatly contribute to their own high adaptive capacity through inventiveness, flexibility and a high knowledge base. Although the future climate will entail hotter temperatures, farmers can be seen as generally well equipped to deal with these challenges because of the high adaptive capacity they currently have and utilize. Those that are most vulnerable are those that have difficulty to access credit e.g. animal farmers and those that do not want to change their agricultural systems e.g. from pastoral lifestyles to include tourism-based operations.

  • 464.
    Riml, Joakim
    et al.
    SMHI.
    Worman, Anders
    Spatiotemporal decomposition of solute dispersion in watersheds2015In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 51, no 4, p. 2377-2392Article in journal (Refereed)
    Abstract [en]

    Information about the effect of different dispersion mechanisms on the solute response in watersheds is crucial for understanding the temporal dynamics of many water quality problems. However, to quantify these processes from stream water quality time series may be difficult because the governing mechanisms responsible for the concentration fluctuations span a wide range of temporal and spatial scales. In an attempt to address the quantification problem, we propose a novel methodology that includes a spectral decomposition of the watershed solute response using a distributed solute transport model for the network of transport pathways in surface and subsurface water. Closed form solutions of the transport problem in both the Laplace and Fourier domains are used to derive formal expressions of (i) the central temporal moments of a solute pulse response and (ii) the power spectral response of a solute concentration time series. By evaluating high-frequency hydrochemical data from the Upper Hafren Watershed, Wales, we linked the watershed dispersion mechanisms to the damping of the concentration fluctuations in different frequency intervals reflecting various environments responsible for the damping. The evaluation of the frequency-dependent model parameters indicate that the contribution of the different environments to the concentration fluctuations at the watershed effluent varies with period. For the longest periods (predominantly groundwater transport pathways) we found that the frequency typical transport time of chloride was 100 times longer and that sodium had a 2.5 times greater retardation factor compared with the shortest periods (predominantly shallow groundwater and surface water transport pathways).

  • 465. Ceola, S.
    et al.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Baratti, E.
    Bloeschl, G.
    Capell, Réne
    SMHI, Research Department, Hydrology.
    Castellarin, A.
    Freer, J.
    Han, D.
    Hrachowitz, M.
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Hutton, C.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Montanari, A.
    Nijzink, R.
    Parajka, J.
    Toth, E.
    Viglione, A.
    Wagener, T.
    Virtual laboratories: new opportunities for collaborative water science2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 4, p. 2101-2117Article in journal (Refereed)
    Abstract [en]

    Reproducibility and repeatability of experiments are the fundamental prerequisites that allow researchers to validate results and share hydrological knowledge, experience and expertise in the light of global water management problems. Virtual laboratories offer new opportunities to enable these prerequisites since they allow experimenters to share data, tools and pre-defined experimental procedures (i.e. protocols). Here we present the outcomes of a first collaborative numerical experiment undertaken by five different international research groups in a virtual laboratory to address the key issues of reproducibility and repeatability. Moving from the definition of accurate and detailed experimental protocols, a rainfall-runoff model was independently applied to 15 European catchments by the research groups and model results were collectively examined through a web-based discussion. We found that a detailed modelling protocol was crucial to ensure the comparability and reproducibility of the proposed experiment across groups. Our results suggest that sharing comprehensive and precise protocols and running the experiments within a controlled environment (e.g. virtual laboratory) is as fundamental as sharing data and tools for ensuring experiment repeatability and reproducibility across the broad scientific community and thus advancing hydrology in a more coherent way.

  • 466. Hytteborn, Julia K.
    et al.
    Temnerud, Johan
    SMHI, Research Department, Hydrology.
    Alexander, Richard B.
    Boyer, Elizabeth W.
    Futter, Martyn N.
    Froberg, Mats
    Dahne, Joel
    SMHI, Professional Services.
    Bishop, Kevin H.
    Patterns and predictability in the intra-annual organic carbon variability across the boreal and hemiboreal landscape2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 520, p. 260-269Article in journal (Refereed)
    Abstract [en]

    Factors affecting total organic carbon (TOC) concentrations in 215 watercourses across Sweden were investigated using parameter parsimonious regression approaches to explain spatial and temporal variabilities of the TOC water quality responses. We systematically quantified the effects of discharge, seasonality, and long-term trend as factors controlling intra-annual (among year) and inter-annual (within year) variabilities of TOC by evaluating the spatial variability in model coefficients and catchment characteristics (e.g. land cover, retention time, soil type). Catchment area (0.18-47,000 km(2)) and land cover types (forests, agriculture and alpine terrain) are typical for the boreal and hemiboreal zones across Fennoscandia. Watercourses had at least 6 years of monthly water quality observations between 1990 and 2010. Statistically significant models (p < 0.05) describing variation of TOC in streamflow were identified in 209 of 215 watercourses with a mean Nash-Sutcliffe efficiency index of 0.44. Increasing long-term trends were observed in 149 (70%) of the watercourses, and intra-annual variation in TOC far exceeded inter-annual variation. The average influences of the discharge and seasonality terms on intra-annual variations in daily TOC concentration were 1.4 and 1.3 mg l(-1) (13 and 12% of the mean annual TOC), respectively. The average increase in TOC was 0.17 mg l(-1) year(-1) (1.6% year(-1)). Multivariate regression with over 90 different catchment characteristics explained 21% of the spatial variation in the linear trend coefficient, less than 20% of the variation in the discharge coefficient and 73% of the spatial variation in mean TOC. Specific discharge, water residence time, the variance of daily precipitation, and lake area, explained 45% of the spatial variation in the amplitude of the TOC seasonality. Because the main drivers of temporal variability in TOC are seasonality and discharge, first-order estimates of the influences of climatic variability and change on TOC concentration should be predictable if the studied catchments continue to respond similarly. (C) 2015 Elsevier B.V. All rights reserved.

  • 467. Falter, Daniela
    et al.
    Schroeter, Kai
    Dung, Nguyen Viet
    Vorogushyn, Sergiy
    Kreibich, Heidi
    Hundecha, Yeshewatesfa
    SMHI, Research Department, Hydrology.
    Apel, Heiko
    Merz, Bruno
    Spatially coherent flood risk assessment based on long-term continuous simulation with a coupled model chain2015In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 524, p. 182-193Article in journal (Refereed)
    Abstract [en]

    A novel approach for assessing flood risk in river catchments in a spatially consistent way is presented. The approach is based on a set of coupled models representing the complete flood risk chain, including a multisite, multivariate weather generator, a hydrological model, a coupled 1D-2D hydrodynamic model and a flood loss model. The approach is exemplarily developed for the meso-scale Mulde catchment in Germany. 10,000 years of meteorological fields at daily resolution are generated and used as input to the subsequent models, yielding 10,000 years of spatially consistent river discharge series, inundation patterns and damage values. This allows estimating flood risk directly from the simulated damage. The benefits of the presented approach are: (1) in contrast to traditional flood risk assessments, where homogenous return periods are assumed for the entire catchment, the approach delivers spatially heterogeneous patterns of precipitation, discharge, inundation and damage patterns which respect the spatial correlations of the different processes and their spatial interactions. (2) Catchment and floodplain processes are represented in a holistic way, since the complete chain of flood processes is represented by the coupled models. For instance, the effects of spatially varying antecedent catchment conditions on flood hydrographs are implicitly taken into account. (3) Flood risk is directly derived from damage yielding a more realistic representation of flood risk. Traditionally, the probability of discharge is used as proxy for the probability of damage. However, non-linearities and threshold behaviour along the flood risk chain contribute to substantial variability between damage probabilities and corresponding discharge probabilities. (C) 2015 Elsevier B.V. All rights reserved.

  • 468. Sein, Dmitry V.
    et al.
    Mikolajewicz, Uwe
    Gröger, Matthias
    SMHI, Research Department, Oceanography.
    Fast, Irina
    Cabos, William
    Pinto, Joaquim G.
    Hagemann, Stefan
    Semmler, Tido
    Izquierdo, Alfredo
    Jacob, Daniela
    Regionally coupled atmosphere-ocean-sea ice-marine biogeochemistry model ROM: 1. Description and validation2015In: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 7, no 1, p. 268-304Article in journal (Refereed)
    Abstract [en]

    The general circulation models used to simulate global climate typically feature resolution too coarse to reproduce many smaller-scale processes, which are crucial to determining the regional responses to climate change. A novel approach to downscale climate change scenarios is presented which includes the interactions between the North Atlantic Ocean and the European shelves as well as their impact on the North Atlantic and European climate. The goal of this paper is to introduce the global ocean-regional atmosphere coupling concept and to show the potential benefits of this model system to simulate present-day climate. A global ocean-sea ice-marine biogeochemistry model (MPIOM/HAMOCC) with regionally high horizontal resolution is coupled to an atmospheric regional model (REMO) and global terrestrial hydrology model (HD) via the OASIS coupler. Moreover, results obtained with ROM using NCEP/NCAR reanalysis and ECHAM5/MPIOM CMIP3 historical simulations as boundary conditions are presented and discussed for the North Atlantic and North European region. The validation of all the model components, i.e., ocean, atmosphere, terrestrial hydrology, and ocean biogeochemistry is performed and discussed. The careful and detailed validation of ROM provides evidence that the proposed model system improves the simulation of many aspects of the regional climate, remarkably the ocean, even though some biases persist in other model components, thus leaving potential for future improvement. We conclude that ROM is a powerful tool to estimate possible impacts of climate change on the regional scale.

  • 469. Pechlivanidis, G. I.
    et al.
    Keramaris, E.
    Pechlivanidis, Ilias
    SMHI, Research Department, Hydrology.
    Samaras, G. A.
    Shear stress estimation in the linear zone over impermeable and permeable beds in open channels2015In: Desalination and Water Treatment, ISSN 1944-3994, E-ISSN 1944-3986, Vol. 54, no 8, p. 2181-2189Article in journal (Refereed)
    Abstract [en]

    This paper investigates the shear stresses in the linear zone of open channel flows with permeable and impermeable bed. The permeable bed is simulated using a flexible vegetation of 2 cm thickness. Laboratory experiments were used for the calculation of the turbulent velocity profiles. The measurements were obtained using a two-dimensional (2D) particle image velocimetry (PIV). This optical method of fluid visualization is used to obtain instantaneous velocity measurements related properties in the fluids. The PIV method assumes that the particles of a fluid faithfully follow the flow dynamics; hence the motion of these seeding particles is used to calculate the dynamic characteristics of the flow. The measurements were conducted at a 12 x 10 cm(2) region located 4 m away from the channel's entrance, where the flow is considered fully developed. The uniformity of the flow was checked measuring the flow depth at two cross-sections (2 m distance between the two regions). The total discharge was estimated using a calibrated venture apparatus. Measurements of velocity were taken for the horizontal channel slope. Results showed that the type of bed can significantly influence the shear stress definition in the linear zone.

  • 470. Haerter, Jan O.
    et al.
    Eggert, Bastian
    Moseley, Christopher
    Piani, Claudio
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Statistical precipitation bias correction of gridded model data using point measurements2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 6, p. 1919-1929Article in journal (Refereed)
    Abstract [en]

    It is well known that climate model output data cannot be used directly as input to impact models, e.g., hydrology models, due to climate model errors. Recently, it has become customary to apply statistical bias correction to achieve better statistical correspondence to observational data. As climate model output should be interpreted as the space-time average over a given model grid box and output time step, the status quo in bias correction is to employ matching gridded observational data to yield optimal results. Here we show that when gridded observational data are not available, statistical bias correction can be carried out using point measurements, e.g., rain gauges. Our nonparametric method, which we call scale-adapted statistical bias correction (SABC), is achieved by data aggregation of either the available modeled or gauge data. SABC is a straightforward application of the well-known Taylor hypothesis of frozen turbulence. Using climate model and rain gauge data, we show that SABC performs significantly better than equal-time period statistical bias correction.

  • 471.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Kawamura, Akira
    Impact of RCM Spatial Resolution on the Reproduction of Local, Subdaily Precipitation2015In: Journal of Hydrometeorology, ISSN 1525-755X, E-ISSN 1525-7541, Vol. 16, no 2, p. 534-547Article in journal (Refereed)
    Abstract [en]

    Many hydrological hazards are closely connected to local precipitation (extremes), especially in small and urban catchments. The use of regional climate model (RCM) data for small-scale hydrological climate change impact assessment has long been nearly unfeasible because of the low spatial resolution. The RCM resolution is, however, rapidly increasing, approaching the size of small catchments and thus potentially increasing the applicability of RCM data for this purpose. The objective of this study is to explore to what degree subhourly temporal precipitation statistics in an RCM converge to observed point statistics when gradually increasing the resolution from 50 to 6 km. This study uses precipitation simulated by RCA3 at seven locations in southern Sweden during 1995-2008. A positive impact of higher resolution was most clearly manifested in 10-yr intensity-duration-frequency (IDF) curves. At 50 km the intensities are underestimated by 50%-90%, but at 6 km they are nearly unbiased, when averaged over all locations and durations. Thus, at 6 km, RCA3 apparently generates low-frequency subdaily extremes that resemble the values found in point observations. Also, the reproduction of short-term variability and less extreme maxima were overall improved with increasing resolution. For monthly totals, a slightly increased overestimation with increasing resolution was found. The bias in terms of wet fraction and wet spell characteristics was overall not strongly dependent on resolution. These metrics are, however, influenced by the cutoff threshold used to separate between wet and dry time steps as well as the wet spell definition.

  • 472.
    Wang, Shiyu
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Development and evaluation of a new regional coupled atmosphere-ocean model in the North Sea and Baltic Sea2015In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 24284Article in journal (Refereed)
    Abstract [en]

    A new regional coupled model system for the North Sea and the Baltic Sea is developed, which is composed of the regional setup of ocean model NEMO, the Rossby Centre regional climate model RCA4, the sea ice model LIM3 and the river routing model CaMa-Flood. The performance of this coupled model system is assessed using a simulation forced with ERA-Interim reanalysis data at the lateral boundaries during the period 1979-2010. Compared to observations, this coupled model system can realistically simulate the present climate. Since the active coupling area covers the North Sea and Baltic Sea only, the impact of the ocean on the atmosphere over Europe is small. However, we found some local, statistically significant impacts on surface parameters like 2m air temperature and sea surface temperature (SST). A precipitation-SST correlation analysis indicates that both coupled and uncoupled models can reproduce the air-sea relationship reasonably well. However, the coupled simulation gives slightly better correlations even when all seasons are taken into account. The seasonal correlation analysis shows that the air-sea interaction has a strong seasonal dependence. Strongest discrepancies between the coupled and the uncoupled simulations occur during summer. Due to lack of air-sea interaction, in the Baltic Sea in the uncoupled atmosphere-standalone run the correlation between precipitation and SST is too small compared to observations, whereas the coupled run is more realistic. Further, the correlation analysis between heat flux components and SST tendency suggests that the coupled model has a stronger correlation. Our analyses show that this coupled model system is stable and suitable for different climate change studies.

  • 473. Archfield, Stacey A.
    et al.
    Clark, Martyn
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Hay, Lauren E.
    McMillan, Hilary
    Kiang, Julie E.
    Seibert, Jan
    Hakala, Kirsti
    Bock, Andrew
    Wagener, Thorsten
    Farmer, William H.
    Andreassian, Vazken
    Attinger, Sabine
    Viglione, Alberto
    Knight, Rodney
    Markstrom, Steven
    Over, Thomas
    Accelerating advances in continental domain hydrologic modeling2015In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 51, no 12, p. 10078-10091Article in journal (Refereed)
    Abstract [en]

    In the past, hydrologic modeling of surface water resources has mainly focused on simulating the hydrologic cycle at local to regional catchment modeling domains. There now exists a level of maturity among the catchment, global water security, and land surface modeling communities such that these communities are converging toward continental domain hydrologic models. This commentary, written from a catchment hydrology community perspective, provides a review of progress in each community toward this achievement, identifies common challenges the communities face, and details immediate and specific areas in which these communities can mutually benefit one another from the convergence of their research perspectives. Those include: (1) creating new incentives and infrastructure to report and share model inputs, outputs, and parameters in data services and open access, machine-independent formats for model replication or reanalysis; (2) ensuring that hydrologic models have: sufficient complexity to represent the dominant physical processes and adequate representation of anthropogenic impacts on the terrestrial water cycle, a process-based approach to model parameter estimation, and appropriate parameterizations to represent large-scale fluxes and scaling behavior; (3) maintaining a balance between model complexity and data availability as well as uncertainties; and (4) quantifying and communicating significant advancements toward these modeling goals.

  • 474.
    Yang, Wei
    et al.
    SMHI, Research Department, Hydrology.
    Gardelin, Marie
    SMHI, Professional Services.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Multi-variable bias correction: application of forest fire risk in present and future climate in Sweden2015In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 15, no 9, p. 2037-2057Article in journal (Refereed)
    Abstract [en]

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

  • 475. Golbeck, Inga
    et al.
    Li, Xin
    Janssen, Frank
    Bruening, Thorger
    Nielsen, Jacob W.
    Huess, Vibeke
    Soderkvist, Johan
    Buchmann, Bjarne
    Siiria, Simo-Matti
    Vaha-Piikkio, Olga
    Hackett, Bruce
    Kristensen, Nils M.
    Engedahl, Harald
    Blockley, Ed
    Sellar, Alistair
    Lagemaa, Priidik
    Ozer, Jose
    Legrand, Sebastien
    Ljungemyr, Patrik
    SMHI, Core Services.
    Axell, Lars
    SMHI, Research Department, Oceanography.
    Uncertainty estimation for operational ocean forecast products-a multi-model ensemble for the North Sea and the Baltic Sea2015In: Ocean Dynamics, ISSN 1616-7341, E-ISSN 1616-7228, Vol. 65, no 12, p. 1603-1631Article in journal (Refereed)
    Abstract [en]

    Multi-model ensembles for sea surface temperature (SST), sea surface salinity (SSS), sea surface currents (SSC), and water transports have been developed for the North Sea and the Baltic Sea using outputs from several operational ocean forecasting models provided by different institutes. The individual models differ in model code, resolution, boundary conditions, atmospheric forcing, and data assimilation. The ensembles are produced on a daily basis. Daily statistics are calculated for each parameter giving information about the spread of the forecasts with standard deviation, ensemble mean and median, and coefficient of variation. High forecast uncertainty, i.e., for SSS and SSC, was found in the Skagerrak, Kattegat (Transition Area between North Sea and Baltic Sea), and the Norwegian Channel. Based on the data collected, longer-term statistical analyses have been done, such as a comparison with satellite data for SST and evaluation of the deviation between forecasts in temporal and spatial scale. Regions of high forecast uncertainty for SSS and SSC have been detected in the Transition Area and the Norwegian Channel where a large spread between the models might evolve due to differences in simulating the frontal structures and their movements. A distinct seasonal pattern could be distinguished for SST with high uncertainty between the forecasts during summer. Forecasts with relatively high deviation from the multi-model ensemble (MME) products or the other individual forecasts were detected for each region and each parameter. The comparison with satellite data showed that the error of the MME products is lowest compared to those of the ensemble members.

  • 476. Wells, Mark L.
    et al.
    Trainer, Vera L.
    Smayda, Theodore J.
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Trick, Charles G.
    Kudela, Raphael M.
    Ishikawa, Akira
    Bernard, Stewart
    Wulff, Angela
    Anderson, Donald M.
    Cochlan, William P.
    Harmful algal blooms and climate change: Learning from the past and present to forecast the future2015In: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 49, p. 68-93Article in journal (Refereed)
    Abstract [en]

    Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB "best practices" manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human wellbeing. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts. (C) 2015 Elsevier B.V. All rights reserved.

  • 477.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Large-scale hydrological modelling by using modified PUB recommendations: the India-HYPE case2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 11, p. 4559-4579Article in journal (Refereed)
    Abstract [en]

    The scientific initiative Prediction in Ungauged Basins (PUB) (2003-2012 by the IAHS) put considerable effort into improving the reliability of hydrological models to predict flow response in ungauged rivers. PUB's collective experience advanced hydrologic science and defined guidelines to make predictions in catchments without observed runoff data. At present, there is a raised interest in applying catchment models to large domains and large data samples in a multi-basin manner, to explore emerging spatial patterns or learn from comparative hydrology. However, such modelling involves additional sources of uncertainties caused by the inconsistency between input data sets, i.e. particularly regional and global databases. This may lead to inaccurate model parameterisation and erroneous process understanding. In order to bridge the gap between the best practices for flow predictions in single catchments and multi-basins at the large scale, we present a further developed and slightly modified version of the recommended best practices for PUB by Takeuchi et al. (2013). By using examples from a recent HYPE (Hydrological Predictions for the Environment) hydrological model set-up across 6000 subbasins for the Indian subcontinent, named India-HYPE v1.0, we explore the PUB recommendations, identify challenges and recommend ways to overcome them. We describe the work process related to (a) errors and inconsistencies in global databases, unknown human impacts, and poor data quality; (b) robust approaches to identify model parameters using a stepwise calibration approach, remote sensing data, expert knowledge, and catchment similarities; and (c) evaluation based on flow signatures and performance metrics, using both multiple criteria and multiple variables, and independent gauges for "blind tests". The results show that despite the strong physiographical gradient over the subcontinent, a single model can describe the spatial variability in dominant hydrological processes at the catchment scale. In addition, spatial model deficiencies are used to identify potential improvements of the model concept. Eventually, through simultaneous calibration using numerous gauges, the median Kling-Gupta efficiency for river flow increased from 0.14 to 0.64. We finally demonstrate the potential of multi-basin modelling for comparative hydrology using PUB, by grouping the 6000 subbasins based on similarities in flow signatures to gain insights into the spatial patterns of flow generating processes at the large scale.

  • 478.
    Hordoir, Robinson
    et al.
    SMHI, Research Department, Oceanography.
    Axell, Lars
    SMHI, Research Department, Oceanography.
    Löptien, Ulrike
    SMHI, Research Department, Oceanography.
    Dietze, Heiner
    Kuznetsov, Ivan
    SMHI, Research Department, Oceanography.
    Influence of sea level rise on the dynamics of salt inflows in the Baltic Sea2015In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 120, no 10, p. 6653-6668Article in journal (Refereed)
    Abstract [en]

    The Baltic Sea is a marginal sea, located in a highly industrialized region in Central Northern Europe. Saltwater inflows from the North Sea and associated ventilation of the deep exert crucial control on the entire Baltic Sea ecosystem. This study explores the impact of anticipated sea level changes on the dynamics of those inflows. We use a numerical oceanic general circulation model covering both the Baltic and the North Sea. The model successfully retraces the essential ventilation dynamics throughout the period 1961-2007. A suite of idealized experiments suggests that rising sea level is associated with intensified ventilation as saltwater inflows become stronger, longer, and more frequent. Expressed quantitatively as a salinity increase in the deep central Baltic Sea, we find that a sea level rise of 1 m triggers a saltening of more than 1 PSU. This substantial increase in ventilation is the consequence of the increasing cross section in the Danish Straits amplified by a reduction of vertical mixing.

  • 479. Andersson, Agneta
    et al.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Ripszam, Matyas
    Rowe, Owen
    Wikner, Johan
    Haglund, Peter
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Legrand, Catherine
    Figueroa, Daniela
    Paczkowska, Joanna
    Lindehoff, Elin
    Tysklind, Mats
    Elmgren, Ragnar
    Projected future climate change and Baltic Sea ecosystem management2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, p. S345-S356Article in journal (Refereed)
    Abstract [en]

    Climate change is likely to have large effects on the Baltic Sea ecosystem. Simulations indicate 2-4 degrees C warming and 50-80 % decrease in ice cover by 2100. Precipitation may increase similar to 30 % in the north, causing increased land runoff of allochthonous organic matter (AOM) and organic pollutants and decreased salinity. Coupled physical-biogeochemical models indicate that, in the south, bottom-water anoxia may spread, reducing cod recruitment and increasing sediment phosphorus release, thus promoting cyanobacterial blooms. In the north, heterotrophic bacteria will be favored by AOM, while phytoplankton production may be reduced. Extra trophic levels in the food web may increase energy losses and consequently reduce fish production. Future management of the Baltic Sea must consider the effects of climate change on the ecosystem dynamics and functions, as well as the effects of anthropogenic nutrient and pollutant load. Monitoring should have a holistic approach, encompassing both autotrophic (phytoplankton) and heterotrophic (e.g., bacterial) processes.

  • 480. Deng, Junjie
    et al.
    Harff, Jan
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A method for assessing the coastline recession due to the sea level rise by assuming stationary wind-wave climate2015In: OCEANOLOGICAL AND HYDROBIOLOGICAL STUDIES, ISSN 1730-413X, Vol. 44, no 3, p. 362-380Article in journal (Refereed)
    Abstract [en]

    The method introduced in this study for future projection of coastline changes hits the vital need of communicating the potential climate change impact on the coast in the 21th century. A quantitative method called the Dynamic Equilibrium Shore Model (DESM) has been developed to hindcast historical sediment mass budgets and to reconstruct a paleo Digital Elevation Model (DEM). The forward mode of the DESM model relies on paleo-scenarios reconstructed by the DESM model assuming stationary wind-wave climate. A linear relationship between the sea level, coastline changes and sediment budget is formulated and proven by the least square regression method. In addition to its forward prediction of coastline changes, this linear relationship can also estimate the sediment budget by using the information on the coastline and relative sea level changes. Wind climate change is examined based on regional climate model data. Our projections for the end of the 21st century suggest that the wind and wave climates in the southern Baltic Sea may not change compared to present conditions and that the investigated coastline along the Pomeranian Bay may retreat from 10 to 100 m depending on the location and on the sea level rise which was assumed to be in the range of 0.12 to 0.24 m.

  • 481. Vuorinen, Ilppo
    et al.
    Hanninen, Jari
    Rajasilta, Marjut
    Laine, Paivi
    Eklund, Jan
    Montesino-Pouzols, Federico
    Corona, Francesco
    Junker, Karin
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Dippner, Joachim W.
    Scenario simulations of future salinity and ecological consequences in the Baltic Sea and adjacent North Sea areas - Implications for environmental monitoring (vol 50, pg 196, 2015)2015In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 53, p. 294-294Article in journal (Refereed)
  • 482. Fosser, G.
    et al.
    Khodayar, S.
    Berg, Peter
    SMHI, Research Department, Hydrology.
    Benefit of convection permitting climate model simulations in the representation of convective precipitation2015In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 44, no 1-2, p. 45-60Article in journal (Refereed)
    Abstract [en]

    A major source of uncertainty in regional climate model (RCM) simulations arises from the parameterisation of sub-grid scale convection. With increasing model resolution, approaching the so-called convection permitting scale, it is possible to switch off most of the convection parameterisations. A set of simulations using COSMO-CLM model has been carried out at different resolutions in order to investigate possible improvements and limitations resulting from increased horizontal resolution. For our analysis, 30 years were simulated in a triple nesting setup with 50, 7 and 2.8 km resolutions, with ERA40 reanalysis data at the lateral boundaries of the coarsest nest. The investigation area covers the state of Baden-Wurttemberg in southwestern Germany, which is a region known for abundant orographically induced convective precipitation. A very dense network of high temporal resolution rain gauges is used for evaluation of the model simulations. The purpose of this study is to examine the differences between the 7 and 2.8 km resolutions in the representation of precipitation at sub-daily timescales, and the atmospheric conditions leading to convection. Our results show that the highest resolution of RCM simulations significantly improves the representation of both hourly intensity distribution and diurnal cycle of precipitation. In addition, at convection permitting scale the atmospheric fields related to convective precipitation show a better agreement with each other. The results imply that higher spatial resolution partially improves the representation of the precipitation field, which must be the way forward for regional climate modelling.

  • 483.
    Olsson, Jonas
    et al.
    SMHI, Research Department, Hydrology.
    Simonsson, Lennart
    SMHI, Research Department, Hydrology.
    Ridal, Martin
    SMHI, Research Department, Meteorology.
    Rainfall nowcasting: predictability of short-term extremes in Sweden2015In: Urban Water Journal, ISSN 1573-062X, Vol. 12, no 1, p. 3-13Article in journal (Refereed)
    Abstract [en]

    Our current knowledge of the character of rainfall events in Sweden associated with extreme short-term accumulations and their predictability by forecasting, is very limited. In this study, observations from automatic stations and weather radars in Sweden were analysed to identify and characterise extreme short-term events. Often shorter-duration (1-6 h) extreme events were associated with small-scale structures, dominated by single cells, and longer-duration (12-24 h) events with less variable, larger-scale fields. For lead time 3 h, similar to 20% of the events were forecasted at the correct place with an error of <25% by the operational Swedish nowcasting system. If allowing for a 25 km displacement of the forecasted events, the hit rate increased by 10-15 percentage points. Some predictability was found for lead time 8 h but not for 24 h. The results suggest a potential added gain of increasing the temporal resolution of the Swedish flood forecasting system to sub-daily steps.

  • 484.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Kuznetsov, Ivan
    Hall, Per O. J.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A new approach to model oxygen dependent benthic phosphate fluxes in the Baltic Sea2015In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 144, p. 127-141Article in journal (Refereed)
    Abstract [en]

    The new approach to model the oxygen dependent phosphate release by implementing formulations of the oxygen penetration depths (OPD) and mineral bound inorganic phosphorus pools to the Swedish Coastal and Ocean Biogeochemical model (SCOBI) is described. The phosphorus dynamics and the oxygen concentrations in the Baltic proper sediment are studied during the period 1980-2008 using SCOBI coupled to the 3D-Rossby Centre Ocean model. Model data are compared to observations from monitoring stations and experiments. The impact from oxygen consumption on the determination of the OPD is found to be largest in the coastal zones where also the largest OPD are found. In the deep water the low oxygen concentrations mainly determine the OPD. Highest modelled release rate of phosphate from the sediment is about 59 x 10(3) t P year(-1) and is found on anoxic sediment at depths between 60-150 m, corresponding to 17% of the Baltic proper total area. The deposition of organic and inorganic phosphorus on sediments with oxic bottom water is larger than the release of phosphorus, about 43 x 10(3) t P year(-1). For anoxic bottoms the release of total phosphorus during the investigated period is larger than the deposition, about 19 x 10(3) t P year(-1). In total the net Baltic proper sediment sink is about 23.7 x 10(3) t P year(-1). The estimated phosphorus sink efficiency of the entire Baltic Sea is on average about 83% during the period. (C) 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

  • 485.
    Pechlivanidis, Ilias
    et al.
    SMHI, Research Department, Hydrology.
    Olsson, Jonas
    SMHI, Research Department, Hydrology.
    Sharma, D.
    Bosshard, Thomas
    SMHI, Research Department, Hydrology.
    Sharma, K. C.
    ASSESSMENT OF THE CLIMATE CHANGE IMPACTS ON THE WATER RESOURCES OF THE LUNI REGION, INDIA2015In: GLOBAL NEST JOURNAL, ISSN 1790-7632, Vol. 17, no 1, p. 29-40Article in journal (Refereed)
    Abstract [en]

    Climate change is expected to have a strong impact on water resources at the local, regional and global scales. In this study, the impact of climate change on the hydro-climatology of the Luni region, India, is investigated by comparing statistics of current and projected future fluxes resulting from three representative concentration pathways (RCP2.6, RCP4.5, and RCP8.5). The use of different scenarios allows for the estimation of uncertainty of future impacts. The projections are based on the CORDEX-South Asia framework and are bias-corrected using the DBS method before being entered into the HYPE (HYdrological Predictions for the Environment) hydrological model to generate predictions of runoff, evapotranspiration, soil moisture deficit, and applied irrigation water to soil. Overall, the high uncertainty in the climate projections is propagated in the impact model, and as a result the spatiotemporal distribution of change is subject to the climate change scenario. In general, for all scenarios, results show a -20 to +20% change in the long-term average precipitation and evapotranspiration, whereas more pronounced impacts are expected for runoff (-40 to +40% change). Climate change can also affect other hydro-climatic components, however, at a lower impact. Finally, the flow dynamics in the Luni River are substantially affected in terms of shape and magnitude.

  • 486.
    Pemberton, Per
    et al.
    SMHI, Research Department, Oceanography.
    Nilsson, Johan
    Hieronymus, Magnus
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Arctic Ocean Water Mass Transformation in S-T Coordinates2015In: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 45, no 4, p. 1025-1050Article in journal (Refereed)
    Abstract [en]

    In this paper, watermass transformations in the Arctic Ocean are studied using a recently developed salinity-temperature (S-T) framework. The framework allows the water mass transformations to be succinctly quantified by computing the surface and internal diffusive fluxes in S-T coordinates. This study shows how the method can be applied to a specific oceanic region, in this case the Arctic Ocean, by including the advective exchange of water masses across the boundaries of the region. Based on a simulation with a global ocean circulation model, the authors examine the importance of various parameterized mixing processes and surface fluxes for the transformation of water across isohaline and isothermal surfaces in the ArcticOcean. The model-based results reveal a broadly realistic Arctic Ocean where the inflowing Atlantic and Pacific waters are primarily cooled and freshened before exiting back to the North Atlantic. In the model, the water mass transformation in the T direction is primarily accomplished by the surface heat flux. However, the surface freshwater flux plays a minor role in the transformation of water toward lower salinities, which is mainly driven by a downgradient mixing of salt in the interior ocean. Near the freezing line, the seasonal melt and growth of sea ice influences the transformation pattern.

  • 487.
    Arheimer, Berit
    et al.
    SMHI, Research Department, Hydrology.
    Lindström, Göran
    SMHI, Research Department, Hydrology.
    Climate impact on floods: changes in high flows in Sweden in the past and the future (1911-2100)2015In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 19, no 2, p. 771-784Article in journal (Refereed)
    Abstract [en]

    There is an ongoing discussion whether floods occur more frequently today than in the past, and whether they will increase in number and magnitude in the future. To explore this issue in Sweden, we merged observed time series for the past century from 69 gauging sites throughout the country (450 000 km(2)) with high-resolution dynamic model projections of the upcoming century. The results show that the changes in annual maximum daily flows in Sweden oscillate between dry and wet periods but exhibit no significant trend over the past 100 years. Temperature was found to be the strongest climate driver of changes in river high flows, which are related primarily to snowmelt in Sweden. Annual daily high flows may decrease by on average -1% per decade in the future, mainly due to lower peaks from snowmelt in the spring (-2% per decade) as a result of higher temperatures and a shorter snow season. In contrast, autumn flows may increase by + 3% per decade due to more intense rainfall. This indicates a shift in floodgenerating processes in the future, with greater influence of rain-fed floods. Changes in climate may have a more significant impact on some specific rivers than on the average for the whole country. Our results suggest that the temporal pattern in future daily high flow in some catchments will shift in time, with spring floods in the northern-central part of Sweden occurring about 1 month earlier than today. High flows in the southern part of the country may become more frequent. Moreover, the current boundary between snow-driven floods in northern-central Sweden and rain-driven floods in the south may move toward higher latitudes due to less snow accumulation in the south and at low altitudes. The findings also indicate a tendency in observations toward the modeled projections for timing of daily high flows over the last 25 years. Uncertainties related to both the observed data and the complex model chain of climate impact assessments in hydrology are discussed.

  • 488. Vuorinen, Ilppo
    et al.
    Hanninen, Jari
    Rajasilta, Marjut
    Laine, Paivi
    Eklund, Jan
    Montesino-Pouzols, Federico
    Corona, Francesco
    Junker, Karin
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Dippner, Joachim W.
    Scenario simulations of future salinity and ecological consequences in the Baltic Sea and adjacent North Sea areas-implications for environmental monitoring2015In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 50, p. 196-205Article in journal (Refereed)
    Abstract [en]

    Substantial ecological changes occurred in the 1970s in the Northern Baltic during a temporary period of low salinity (S). This period was preceded by an episodic increase in the rainfall over the Baltic Sea Watershed area. Several climate models, both global and regional, project an increase in the runoff of the Northern latitudes due to proceeding climate change. The aim of this study is to model, firstly, the effects on Baltic Sea salinity of increased runoff due to projected global change and, secondly, the effects of salinity change on the distribution of marine species. The results suggest a critical shift in the S range 5-7, which is a threshold for both freshwater and marine species distributions and diversity. We discuss several topics emphasizing future monitoring, modelling, and fisheries research. Environmental monitoring and modelling are investigated because the developing alternative ecosystems do not necessarily show the same relations to environment quality factors as the retiring ones. An important corollary is that the observed and modelled S changes considered together with species' ranges indicate what may appear under a future climate. Consequences could include a shift in distribution areas of marine benthic foundation species and some 40-50 other species, affiliated to these. This change would extend over hundreds of kilometres, in the Baltic Sea and the adjacent North Sea areas. Potential cascading effects, in coastal ecology, fish ecology and fisheries would be extensive, and point out the necessity to develop further the "ecosystem approach in the environmental monitoring". (C) 2014 The Authors. Published by Elsevier Ltd.

  • 489. Borsche, M.
    et al.
    Kaiser-Weiss, A. K.
    Undén, Per
    SMHI, Research Department, Meteorology.
    Kaspar, F.
    Methodologies to characterize uncertainties in regional reanalyses2015In: Advances in Science and Research, ISSN 1992-0628, E-ISSN 1992-0636, Vol. 12, p. 207-218Article in journal (Refereed)
    Abstract [en]

    When using climate data for various applications, users are confronted with the difficulty to assess the uncertainties of the data. For both in-situ and remote sensing data the issues of representativeness, homogeneity, and coverage have to be considered for the past, and their respective change over time has to be considered for any interpretation of trends. A synthesis of observations can be obtained by employing data assimilation with numerical weather prediction (NWP) models resulting in a meteorological reanalysis. Global reanalyses can be used as boundary conditions for regional reanalyses (RRAs), which run in a limited area (Europe in our case) with higher spatial and temporal resolution, and allow for assimilation of more regionally representative observations. With the spatially highly resolved RRAs, which exhibit smaller scale information, a more realistic representation of extreme events (e.g. of precipitation) compared to global reanalyses is aimed for. In this study, we discuss different methods for quantifying the uncertainty of the RRAs to answer the question to which extent the smaller scale information (or resulting statistics) provided by the RRAs can be relied on. Within the European Union's seventh Framework Programme (EU FP7) project Uncertainties in Ensembles of Regional Re-Analyses (UERRA) ensembles of RRAs (both multi-model and single model ensembles) are produced and their uncertainties are quantified. Here we explore the following methods for characterizing the uncertainties of the RRAs: (A) analyzing the feedback statistics of the assimilation systems, (B) validation against station measurements and (C) grids derived thereof, and (D) against gridded satellite data products. The RRA ensembles (E) provide the opportunity to derive ensemble scores like ensemble spread and other special probabilistic skill scores. Finally, user applications (F) are considered. The various methods are related to user questions they can help to answer.

  • 490. Jerez, Sonia
    et al.
    Tobin, Isabelle
    Vautard, Robert
    Pedro Montavez, Juan
    Maria Lopez-Romero, Jose
    Thais, Francoise
    Bartok, Blanka
    Christensen, Ole Bossing
    Colette, Augustin
    Deque, Michel
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Kotlarski, Sven
    van Meijgaard, Erik
    Teichmann, Claas
    Wild, Martin
    The impact of climate change on photovoltaic power generation in Europe2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 10014Article in journal (Refereed)
    Abstract [en]

    Ambitious climate change mitigation plans call for a significant increase in the use of renewables, which could, however, make the supply system more vulnerable to climate variability and changes. Here we evaluate climate change impacts on solar photovoltaic (PV) power in Europe using the recent EURO-CORDEX ensemble of high-resolution climate projections together with a PV power production model and assuming a well-developed European PV power fleet. Results indicate that the alteration of solar PV supply by the end of this century compared with the estimations made under current climate conditions should be in the range (-14%; +2%), with the largest decreases in Northern countries. Temporal stability of power generation does not appear as strongly affected in future climate scenarios either, even showing a slight positive trend in Southern countries. Therefore, despite small decreases in production expected in some parts of Europe, climate change is unlikely to threaten the European PV sector.

  • 491. Jung, Thomas
    et al.
    Doblas-Reyes, Francisco
    Goessling, Helge
    Guemas, Virginie
    Bitz, Cecilia
    Buontempo, Carlo
    Caballero, Rodrigo
    Jakobson, Erko
    Jungclaus, Johann
    Karcher, Michael
    Koenigk, Torben
    SMHI, Research Department, Climate research - Rossby Centre.
    Matei, Daniela
    Overland, James
    Spengler, Thomas
    Yang, Shuting
    POLAR LOWER-LATITUDE LINKAGES AND THEIR ROLE IN WEATHER AND CLIMATE PREDICTION2015In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, no 11, p. ES197-ES200Article in journal (Refereed)
  • 492. Silva, F. C.
    et al.
    Borrego, C.
    Keizer, J. J.
    Amorim, Jorge Humberto
    SMHI, Research Department, Air quality.
    Verheijen, F. G. A.
    Effects of moisture content on wind erosion thresholds of biochar2015In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 123, p. 121-128Article in journal (Refereed)
    Abstract [en]

    Biochar, i.e. pyrolysed biomass, as a soil conditioner is gaining increasing attention in research and industry, with guidelines and certifications being developed for biochar production, storage and handling, as well as for application to soils. Adding water to biochar aims to reduce its susceptibility to become airborne during and after the application to soils, thereby preventing, amongst others, human health issues from inhalation. The Bagnold model has previously been modified to explain the threshold friction velocity of coal particles at different moisture contents, by adding an adhesive effect. However, it is unknown if this model also works for biochar particles. We measured the threshold friction velocities of a range of biochar particles (woody feedstock) under a range of moisture contents by using a wind tunnel, and tested the performance of the modified Bagnold model. Results showed that the threshold friction velocity can be significantly increased by keeping the gravimetric moisture content at or above 15% to promote adhesive effects between the small particles. For the specific biochar of this study, the modified Bagnold model accurately estimated threshold friction velocities of biochar particles up to moisture contents of 10%. (C) 2015 Elsevier Ltd. All rights reserved.

  • 493.
    Norin, Lars
    et al.
    SMHI, Research Department, Atmospheric remote sensing.
    Devasthale, Abhay
    SMHI, Research Department, Atmospheric remote sensing.
    L'Ecuyer, T. S.
    Wood, N. B.
    Smalley, M.
    Intercomparison of snowfall estimates derived from the CloudSat Cloud Profiling Radar and the ground-based weather radar network over Sweden2015In: Atmospheric Measurement Techniques, ISSN 1867-1381, E-ISSN 1867-8548, Vol. 8, no 12, p. 5009-5021Article in journal (Refereed)
    Abstract [en]

    Accurate snowfall estimates are important for both weather and climate applications. Ground-based weather radars and space-based satellite sensors are often used as viable alternatives to rain gauges to estimate precipitation in this context. In particular, the Cloud Profiling Radar (CPR) on board CloudSat is proving to be a useful tool to map snowfall globally, in part due to its high sensitivity to light precipitation and its ability to provide near-global vertical structure. CloudSat snowfall estimates play a particularly important role in the high-latitude regions as other ground-based observations become sparse and passive satellite sensors suffer from inherent limitations. In this paper, snowfall estimates from two observing systems-Swerad, the Swedish national weather radar network, and CloudSat - are compared. Swerad offers a well-calibrated data set of precipitation rates with high spatial and temporal resolution, at very high latitudes. The measurements are anchored to rain gauges and provide valuable insights into the usefulness of CloudSat CPR's snowfall estimates in the polar regions. In total, 7 : 2 x 10(5) matchups of CloudSat and Swerad observations from 2008 through 2010 were intercompared, covering all but the summer months (June to September). The intercomparison shows encouraging agreement between the two observing systems despite their different sensitivities and user applications. The best agreement is observed when CloudSat passes close to a Swerad station (46-82 km), where the observational conditions for both systems are comparable. Larger disagreements outside this range suggest that both platforms have difficulty with shallow snow but for different reasons. The correlation between Swerad and CloudSat degrades with increasing distance from the nearest Swerad station, as Swerad's sensitivity decreases as a function of distance. Swerad also tends to overshoot low-level precipitating systems further away from the station, leading to an underestimation of snowfall rate and occasionally to missing precipitation altogether. Several statistical metrics-including the probability of detection, false alarm rate, hit rate, and Pierce's skill score - are calculated. The sensitivity of these metrics to the snowfall rate, as well as to the distance from the nearest radar station, are summarised. This highlights the strengths and the limitations of both observing systems at the lower and upper ends of the snowfall distributions as well as the range of uncertainties that can be expected from these systems in high-latitude regions.

  • 494. Navarro-Ortega, Alicia
    et al.
    Acuna, Vicenc
    Bellin, Alberto
    Burek, Peter
    Cassiani, Giorgio
    Choukr-Allah, Redouane
    Doledec, Sylvain
    Elosegi, Arturo
    Ferrari, Federico
    Ginebreda, Antoni
    Grathwohl, Peter
    Jones, Colin
    SMHI, Research Department, Climate research - Rossby Centre.
    Rault, Philippe Ker
    Kok, Kasper
    Koundouri, Phoebe
    Ludwig, Ralf Peter
    Merz, Ralf
    Milacic, Radmila
    Munoz, Isabel
    Nikulin, Grigory
    SMHI, Research Department, Climate research - Rossby Centre.
    Paniconi, Claudio
    Paunovic, Momir
    Petrovic, Mira
    Sabater, Laia
    Sabater, Sergi
    Skoulikidis, Nikolaos Th.
    Slob, Adriaan
    Teutsch, Georg
    Voulvoulis, Nikolaos
    Barcelo, Damia
    Managing the effects of multiple stressors on aquatic ecosystems under water scarcity. The GLOBAQUA project2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 503, p. 3-9Article in journal (Refereed)
    Abstract [en]

    Water scarcity is a serious environmental problem in many European regions, and will likely increase in the near future as a consequence of increased abstraction and climate change. Water scarcity exacerbates the effects of multiple stressors, and thus results in decreased water quality. It impacts river ecosystems, threatens the services they provide, and it will force managers and policy-makers to change their current practices. The EU-FP7 project GLOBAQUA aims at identifying the prevalence, interaction and linkages between stressors, and to assess their effects on the chemical and ecological status of freshwater ecosystems in order to improve water management practice and policies. GLOBAQUA assembles a multidisciplinary team of 21 European plus 2 non-European scientific institutions, as well as water authorities and river basin managers. The project includes experts in hydrology, chemistry, biology, geomorphology, modelling, socio-economics, governance science, knowledge brokerage, and policy advocacy. GLOBAQUA studies six river basins (Ebro, Adige, Sava, Evrotas, Anglian and Souss Massa) affected by water scarcity, and aims to answer the following questions: how does water scarcity interact with other existing stressors in the study river basins? How will these interactions change according to the different scenarios of future global change? Which will be the foreseeable consequences for river ecosystems? How will these in turn affect the services the ecosystems provide? How should management and policies be adapted to minimise the ecological, economic and societal consequences? These questions will be approached by combining data-mining, field- and laboratory-based research, and modelling. Here, we outline the general structure of the project and the activities to be conducted within the fourteen work-packages of GLOBAQUA. (C) 2014 The Authors. Published by Elsevier B.V.

  • 495. Watson, Laura
    et al.
    Lacressonniere, Gwendoline
    Gauss, Michael
    Engardt, Magnuz
    SMHI, Research Department, Air quality.
    Andersson, Camilla
    SMHI, Research Department, Air quality.
    Josse, Beatrice
    Marecal, Virginie
    Nyiri, Agnes
    Sobolowski, Stefan
    Siour, Guillaume
    Vautard, Robert
    The impact of meteorological forcings on gas phase air pollutants over Europe2015In: Atmospheric Environment, ISSN 1352-2310, E-ISSN 1873-2844, Vol. 119, p. 240-257Article in journal (Refereed)
    Abstract [en]

    The impact of meteorological forcings on gas phase air pollutants (ozone and nitrogen dioxide) over Europe was studied using four offline chemistry transport models (CTMs) as part of the IMPACT2C project. This study uses long (20- and 30-year) simulations to evaluate the present-day performance of the CTMs, which is a necessary first step before undertaking any analysis of future air quality impacts. Two sets of meteorological forcings were used for each model: reanalysis of past observation data (ERA-Interim) and Global Climate Model (GCM) output. The results for the simulations forced by reanalysis data were assessed in relation to AirBase v7 measurement data, and it was determined that all four models slightly overpredict annual O-3 values (mean biases range between 0.7 and 6.6 ppb) and three out of the four models underpredict observed annual NO2 (mean biases range between -3.1 and -5.2 ppb). The simulations forced by climate models result in spatially averaged monthly concentrations of O-3 that are generally between 0 and 5 ppb higher than the values obtained from simulations forced by reanalysis data; therefore it was concluded that the use of climate models introduces an additional bias to the results, but this bias tends not to be significant in the majority of cases. The bias in O-3 results appears to be correlated mainly to differences in temperature and boundary layer height between the two types of simulations, whereas the less significant bias in NO2 is negatively correlated to temperature and boundary layer height. It is also clear that the selection of chemical boundary conditions is an important factor in determining the variability of O-3 model results. These results will be used as a baseline for the interpretation of future work, which will include an analysis of future climate scenarios upon European air quality. (C) 2015 Elsevier Ltd. All rights reserved.

  • 496. Friman, Mathias
    et al.
    Hjerpe, Mattias
    Agreement, significance, and understandings of historical responsibility in climate change negotiations2015In: Climate Policy, ISSN 1469-3062, E-ISSN 1752-7457, Vol. 15, no 3, p. 302-320Article in journal (Refereed)
    Abstract [en]

    For over 20 years, Parties to the UN Framework Convention on Climate Change have struggled with the normative significance of history for the differentiation of responsibilities. Negotiations on 'historical responsibility' have been marked by considerable conflict between developed and developing countries. However, in 2010, the Parties acknowledged the concept in a consensus decision. This article analyses UN Climate Change Conference delegates' agreement with the decision, whether it reconciled conflict between interpretations of historical responsibility, and the significance that delegates ascribe to the decision for future agreements. The decision has not eliminated conflict between different interpretations. Delegates who understand historical responsibility as linking countries' historical contributions to climate change to their responsibilities to act agree more with the decision and foresee it having a stronger influence on future agreements than do those viewing the concept in more conceptual terms. The decision marks the start of negotiations concerning how rather than whether historical responsibility should guide operative text. This article demonstrates that (1) the divergent interpretations pose clear challenges for a necessary but demanding agreement on operationalization, and (2) focusing on an ambiguous version of proportionality between contribution to change and responsibility can become a first step for convergence between divergent positions.

  • 497. Milano, Marianne
    et al.
    Reynard, Emmanuel
    Koplin, Nina
    SMHI.
    Weingartner, Rolf
    Climatic and anthropogenic changes in Western Switzerland: Impacts on water stress2015In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 536, p. 12-24Article in journal (Refereed)
    Abstract [en]

    Recent observed hydro-climatic changes in mountainous areas are of concern as they may directly affect capacity to fulfill water needs. The canton of Vaud in Western Switzerland is an example of such a region as it has experienced water shortage episodes during the past decade. Based on an integrated modeling framework, this study explores how hydro-climatic conditions and water needs could evolve in mountain environments and assesses their potential impacts on water stress by the 2060 horizon. Flows were simulated based on a daily semi-distributed hydrological model. Future changes were derived from Swiss climate scenarios based on two regional climate models. Regarding water needs, the authorities of the canton of Vaud provided a population growth scenario while irrigation and livestock trends followed a business-as-usual scenario. Currently, the canton of Vaud experiences moderate water stress from June to August, except in its Alpine area where no stress is noted. In the 2060 horizon, water needs could exceed 80% of the rivers' available resources in low-to mid-altitude environments in mid-summer. This arises from the combination of drier and warmer climate that leads to longer and more severe low flows, and increasing urban (+40%) and irrigation (+25%) water needs. Highlighting regional differences supports the development of sustainable development pathways to reduce water tensions. Based on a quantitative assessment, this study also calls for broader impact studies including water quality issues. (C) 2015 Elsevier B.V. All rights reserved.

  • 498. Couvreux, F.
    et al.
    Roehrig, R.
    Rio, C.
    Lefebvre, M. -P
    Caian, Mihaela
    SMHI, Research Department, Climate research - Rossby Centre.
    Komori, T.
    Derbyshire, S.
    Guichard, F.
    Favot, F.
    D'Andrea, F.
    Bechtold, P.
    Gentine, P.
    Representation of daytime moist convection over the semi-arid Tropics by parametrizations used in climate and meteorological models2015In: Quarterly Journal of the Royal Meteorological Society, ISSN 0035-9009, E-ISSN 1477-870X, Vol. 141, no 691, p. 2220-2236Article in journal (Refereed)
    Abstract [en]

    A case of daytime development of deep convection over tropical semi-arid land is used to evaluate the representation of convection in global and regional models. The case is based on observations collected during the African Monsoon Multidisciplinary Analysis (AMMA) field campaign and includes two distinct transition phases, from clear sky to shallow cumulus and from cumulus to deep convection. Different types of models, run with identical initial and boundary conditions, are intercompared: a reference large-eddy simulation (LES), single-column model (SCM) version of four different Earth system models that participated in the Coupled Model Intercomparison Project 5 exercise, the SCM version of the European Centre for Medium-range Weather Forecasts operational forecast model, the SCM version of a mesoscale model and a bulk model. Surface fluxes and radiative heating are prescribed preventing any atmosphere-surface and cloud-radiation coupling in order to simplify the analyses so that it focuses only on convective processes. New physics packages are also evaluated within this framework. As the LES correctly reproduces the observed growth of the boundary layer, the gradual development of shallow clouds, the initiation of deep convection and the development of cold pools, it provides a basis to evaluate in detail the representation of the diurnal cycle of convection by the other models and to test the hypotheses underlying convective parametrizations. Most SCMs have difficulty in representing the timing of convective initiation and rain intensity, although substantial modifications to boundary-layer and deep-convection parametrizations lead to improvements. The SCMs also fail to represent the mid-level troposphere moistening during the shallow convection phase, which we analyse further. Nevertheless, beyond differences in timing of deep convection, the SCM models reproduce the sensitivity to initial and boundary conditions simulated in the LES regarding boundary-layer characteristics, and often the timing of convection triggering.

  • 499.
    Rummukainen, Markku
    et al.
    SMHI, Core Services.
    Rockel, Burkhardt
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Jens Hesselbjerg
    Reckermann, Marcus
    Twenty-First-Century Challenges in Regional Climate Modeling2015In: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 96, no 8, p. ES135-ES138Article in journal (Refereed)
  • 500. Sanchez, E.
    et al.
    Solman, S.
    Remedio, A. R. C.
    Berbery, H.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Da Rocha, R. P.
    Mourao, C.
    Li, L.
    Marengo, J.
    de Castro, M.
    Jacob, D
    Regional climate modelling in CLARIS-LPB: a concerted approach towards twentyfirst century projections of regional temperature and precipitation over South America2015In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 45, no 7-8, p. 2193-2212Article in journal (Refereed)
    Abstract [en]

    The results of an ensemble of regional climate model (RCM) simulations over South America are presented. This is the first coordinated exercise of regional climate modelling studies over the continent, as part of the CLARIS-LPB EU FP7 project. The results of different future periods, with the main focus on (2071-2100) is shown, when forced by several global climate models, all using the A1B greenhouse gases emissions scenario. The analysis is focused on the mean climate conditions for both temperature and precipitation. The common climate change signals show an overall increase of temperature for all the seasons and regions, generally larger for the austral winter season. Future climate shows a precipitation decrease over the tropical region, and an increase over the subtropical areas. These climate change signals arise independently of the driving global model and the RCM. The internal variability of the driving global models introduces a very small level of uncertainty, compared with that due to the choice of the driving model and the RCM. Moreover, the level of uncertainty is larger for longer horizon projections for both temperature and precipitation. The uncertainty in the temperature changes is larger for the subtropical than for the tropical ones. The current analysis allows identification of the common climate change signals and their associated uncertainties for several subregions within the South American continent.

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