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  • 251. Groger, Matthias
    et al.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Thermal air-sea coupling in hindcast simulations for the North Sea and Baltic Sea on the NW European shelf2015Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, artikel-id 26911Artikel i tidskrift (Refereegranskat)
    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.

  • 252. Gustafsson, Bo G.
    et al.
    Schenk, Frederik
    Blenckner, Thorsten
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Muller-Karulis, Barbel
    Neumann, Thomas
    Ruoho-Airola, Tuija
    Savchuk, Oleg P.
    Zorita, Eduardo
    Reconstructing the Development of Baltic Sea Eutrophication 1850-20062012Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, nr 6, s. 534-548Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A comprehensive reconstruction of the Baltic Sea state from 1850 to 2006 is presented: driving forces are reconstructed and the evolution of the hydrography and biogeochemical cycles is simulated using the model BALTSEM. Driven by high resolution atmospheric forcing fields (HiResAFF), BALTSEM reproduces dynamics of salinity, temperature, and maximum ice extent. Nutrient loads have been increasing with a noteworthy acceleration from the 1950s until peak values around 1980 followed by a decrease continuing up to present. BALTSEM shows a delayed response to the massive load increase with most eutrophic conditions occurring only at the end of the simulation. This is accompanied by an intensification of the pelagic cycling driven by a shift from spring to summer primary production. The simulation indicates that no improvement in water quality of the Baltic Sea compared to its present state can be expected from the decrease in nutrient loads in recent decades.

  • 253.
    Göransson, Bent
    et al.
    SMHI, Samhälle och säkerhet.
    Brandt, Maja
    SMHI, Samhälle och säkerhet.
    Wittgren, Hans Bertil
    SMHI, Forskningsavdelningen.
    Markläckage och vattendragstransport av kväve och fosfor i Roxen/Glan-systemet, Östergötland1991Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Markläckage, vattendragstransport och sjöretention av kväve har beräknats med en modell (PULS-N) i de delar av Motala Ströms avrinningsområde, som faller inom Linköpings, Finspångs och Norrköpings kommuner. Modelleringar har gjorts för åren 1975-89 och verifierats mot befintliga mätdata.

    Modellen använder tre olika typer av indata: meterologiska uppgifter om temperatur och nederbörd, geografiska uppgifter om vattendelarnas läge och arealens fördelning på olika markanvändning, samt kemiska data om typiska halter i avrinnande vatten från olika typer åv markanvändning

    Markläckaget av kväve domineras av bidrag från åker med sädesodling. Från de delar av avrinningsområdet, som ungefärligen motsvaras av Linköpings kommun, svarade sädesodling för 31 % av arealen men 76 % av markläckaget. För Finspång var motsvarande siffror 4 resp. 18 % och för Norrköping 9 resp. 32 %. Dessa procentuella uppgifter på markläckaget gäller 1989 men varierar inte nämnvärt mellan olika år.

    Kvävetransporten i vattendragen visar kraftiga mellanårsvariationer, som huvudsakligen förklaras av skillnader i nederbörd. I de fall, då modellerade värden avviker från värden beräknade ur uppmätta koncentrationer, är detta en indikation på förändringar som inte förklaras av väderfaktorer. Exempelvis var 1977 ett år med starkt förhöjd uttransport ur sjön Glan. Uttransporten kan inte förklaras tillfredställande av en motsvarande hög intransport, vilket tyder på en frisättning av kväve från sjösedimenten i Glan.

    Både Roxen och Glan fungerar som kvävefällor. I genomsnitt kvarhölls, på basis av sjöyta, 53 kg/ha·år (17 % ) i Roxen och 36 kg/ha·år (9 % ) i Glan under perioden 1975-89. En orsak till skillnaden är antagligen att nitrat-N-transporten till Roxen är högre än till Glan, trots att total-N-transporten är högre till Glan. Förhållandet mellan nitrat-N och organiskt N i sjöarna speglar att Glan inte är en lika utpräglad slättsjö som Roxen.

    Beräkningarna, med hänsyn tagen till retentionen i sjöarna, visar att punktkällorna (de stora reningsverken och Skärblacka bruk) stod för 27 % av Motala Ströms nettobelastning på Bråviken under perioden 1985-89. Det lokala bidraget från markläckage i de aktuella kommunerna stod för 22 % och intransporten till kommunerna för 51 % .

    Nettotransporterna av fosfor, räknat per ytenhet, är störst inom Linköpings kommuns delar av Svartåns och Motala Ströms (huvudfårans) avrinningsområden.

    Transporten av fosfor från Roxen var under 1975-89 klart större än transporterna till Roxen. Under samma period hade Glan en nettoimport av fosfor.

  • 254. Haapala, J
    et al.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Rinne, J
    Numerical investigations of future ice conditions in the Baltic Sea2001Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 30, nr 4-5, s. 237-244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Global climate change is expected to have an effect on the physical and ecological characteristics of the Baltic Sea. Estimates of future climate on the regional scale can be obtained by using either statistical or dynamical downscaling methods of global AOGCM scenario results. In this paper, we use 2 different coupled ice-ocean models of the Baltic Sea to simulate present and future ice conditions around 100 years from present. Two 10-year time slice experiments have been performed using the results of atmospheric climate model simulations as forcing, one representing pre-industrial climate conditions (control simulation), and the other global warming with a 150% increase in CO2 greenhouse gas concentration (scenario simulation). Present-day climatological ice conditions and interannual variability are realistically reproduced by the models. The simulated range of the maximum annual ice extent in the Baltic in both models together is 180 to 420.10(3) km(2) in the control simulation and 45 to 270.10(3) km(2) in the scenario simulation. The range of the maximum annual ice thickness is from 32 to 96 cm and from 11 to 60 cm in the control and scenario simulations, respectively. In contrast to earlier estimates, sea ice is still formed every winter in the Northern Bothnian Bay and in the most Eastern parts of the Gulf of Finland. Overall, the simulated changes of quantities such as ice extent and ice thickness, as well as their interannual variations are relatively similar in both models, which is remarkable, because the 2 coupled ice-ocean model systems have been. developed independently. This increases the reliability of future projections of ice conditions in the Baltic Sea.

  • 255. Haerter, Jan O.
    et al.
    Berg, Peter
    SMHI, Forskningsavdelningen, Hydrologi.
    Moseley, Christopher
    Precipitation onset as the temporal reference in convective self-organization2017Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, nr 12, s. 6450-6459Artikel i tidskrift (Refereegranskat)
  • 256. Haerter, Jan O.
    et al.
    Eggert, Bastian
    Moseley, Christopher
    Piani, Claudio
    Berg, Peter
    SMHI, Forskningsavdelningen, Hydrologi.
    Statistical precipitation bias correction of gridded model data using point measurements2015Ingår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, nr 6, s. 1919-1929Artikel i tidskrift (Refereegranskat)
    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.

  • 257. Hajdu, S
    et al.
    Edler, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Olenina, I
    Witek, B
    Spreading and establishment of the potentially toxic dinoflagellate Prorocentrum minimum in the Baltic Sea2000Ingår i: International review of hydrobiology, ISSN 1434-2944, E-ISSN 1522-2632, Vol. 85, nr 5-6, s. 561-575Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the last two decades the potentially toxic dinoflagellate Prorocentrum minimum (PAVILLARD) SCHILLER has successfully established itself in the Baltic Sea. It is now a dominant summer species in the southern Baltic proper, and reaches as far into the low salinity of the northern Baltic as the central Gulf of Finland. In the 1990s, it developed several coastal blooms in the eastern and northern Baltic proper, but occurred irregularly between years. Field data show that P. minimum can grow at salinities below 5 PSU, confirming its potential to penetrate farther into the low saline part of the Baltic Sea. Biometric data show that P. minimum cells differ significantly in size between areas in the Baltic Sea.

  • 258. Hakonen, Aron
    et al.
    Anderson, Leif G.
    Engelbrektsson, Johan
    Hulth, Stefan
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    A potential tool for high-resolution monitoring of ocean acidification2013Ingår i: Analytica Chimica Acta, ISSN 0003-2670, E-ISSN 1873-4324, Vol. 786, s. 1-7Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Current anthropogenic carbon dioxide emissions generate besides global warming unprecedented acidification rates of the oceans. Recent evidence indicates the possibility that ocean acidification and low oceanic pH may be a major reason for several mass extinctions in the past. However, a major bottleneck for research on ocean acidification is long-term monitoring and the collection of consistent high-resolution pH measurements. This study presents a low-power (<1 W) small sample volume (25 mu L) semiconductor based fluorescence method for real-time ship-board pH measurements at high temporal and spatial resolution (approximately 15 s and 100 m between samples). A 405 nm light emitting diode and the blue and green channels from a digital camera was used for swift detection of fluorescence from the pH sensitive dye 6,8-Dihydroxypyrene-1,3-disulfonic acid in real-time. Main principles were demonstrated by automated continuous measurements of pH in the surface water across the Baltic Sea and the Kattegat region with a large range in salinity (similar to 3-30) and temperature (similar to 0-25 degrees C). Ship-board precision of salinity and temperature adjusted pH measurements were estimated as low as 0.0001 pH units. (C) 2013 Elsevier B. V. All rights reserved.

  • 259. Hall, J.
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Aronica, T.
    Bilibashi, A.
    Bohac, M.
    Bonacci, O.
    Borga, M.
    Burlando, P.
    Castellarin, A.
    Chirico, G. B.
    Claps, P.
    Fiala, K.
    Gaal, L.
    Gorbachova, L.
    Gul, A.
    Hannaford, J.
    Kiss, A.
    Kjeldsen, T.
    Kohnova, S.
    Koskela, J. J.
    Macdonald, N.
    Mavrova-Guirguinova, M.
    Ledvinka, O.
    Mediero, L.
    Merz, B.
    Merz, R.
    Molnar, P.
    Montanari, A.
    Osuch, M.
    Parajka, J.
    Perdigao, R. A. P.
    Radevski, I.
    Renard, B.
    Rogger, M.
    Salinas, J. L.
    Sauquet, E.
    Sraj, M.
    Szolgay, J.
    Viglione, A.
    Volpi, E.
    Wilson, D.
    Zaimi, K.
    Bloeschl, G.
    A European Flood Database: facilitating comprehensive flood research beyond administrative boundaries2015Ingår i: CHANGES IN FLOOD RISK AND PERCEPTION IN CATCHMENTS AND CITIES, 2015, s. 89-95Konferensbidrag (Refereegranskat)
    Abstract [en]

    The current work addresses one of the key building blocks towards an improved understanding of flood processes and associated changes in flood characteristics and regimes in Europe: the development of a comprehensive, extensive European flood database. The presented work results from ongoing cross-border research collaborations initiated with data collection and joint interpretation in mind. A detailed account of the current state, characteristics and spatial and temporal coverage of the European Flood Database, is presented. At this stage, the hydrological data collection is still growing and consists at this time of annual maximum and daily mean discharge series, from over 7000 hydrometric stations of various data series lengths. Moreover, the database currently comprises data from over 50 different data sources. The time series have been obtained from different national and regional data sources in a collaborative effort of a joint European flood research agreement based on the exchange of data, models and expertise, and from existing international data collections and open source websites. These ongoing efforts are contributing to advancing the understanding of regional flood processes beyond individual country boundaries and to a more coherent flood research in Europe.

  • 260. Hall, J.
    et al.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Borga, M.
    Brazdil, R.
    Claps, P.
    Kiss, A.
    Kjeldsen, T. R.
    Kriauciuniene, J.
    Kundzewicz, Z. W.
    Lang, M.
    Llasat, M. C.
    Macdonald, N.
    McIntyre, N.
    Mediero, L.
    Merz, B.
    Merz, R.
    Molnar, P.
    Montanari, A.
    Neuhold, C.
    Parajka, J.
    Perdigao, R. A. P.
    Plavcova, L.
    Rogger, M.
    Salinas, J. L.
    Sauquet, E.
    Schaer, C.
    Szolgay, J.
    Viglione, A.
    Bloeschl, G.
    Understanding flood regime changes in Europe: a state-of-the-art assessment2014Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 18, nr 7, s. 2735-2772Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    There is growing concern that flooding is becoming more frequent and severe in Europe. A better understanding of flood regime changes and their drivers is therefore needed. The paper reviews the current knowledge on flood regime changes in European rivers that has traditionally been obtained through two alternative research approaches. The first approach is the data-based detection of changes in observed flood events. Current methods are reviewed together with their challenges and opportunities. For example, observation biases, the merging of different data sources and accounting for nonlinear drivers and responses. The second approach consists of modelled scenarios of future floods. Challenges and opportunities associated with flood change scenarios are discussed such as fully accounting for uncertainties in the modelling cascade and feedbacks. To make progress in flood change research, we suggest that a synthesis of these two approaches is needed. This can be achieved by focusing on long duration records and flood-rich and flood-poor periods rather than on short duration flood trends only, by formally attributing causes of observed flood changes, by validating scenarios against observed flood regime dynamics, and by developing low-dimensional models of flood changes and feedbacks. The paper finishes with a call for a joint European flood change research network.

  • 261. Hall, Per O. J.
    et al.
    Almroth-Rosell, Elin
    SMHI, Forskningsavdelningen, Oceanografi.
    Bonaglia, Stefano
    Dale, Andrew W.
    Hylén, Astrid
    Kononets, Mikhail
    Nilsson, Madeleine
    Sommer, Stefan
    van de Velde, Sebastiaan
    Viktorsson, Lena
    SMHI, Samhälle och säkerhet.
    Influence of Natural Oxygenation of Baltic Proper Deep Water on Benthic Recycling and Removal of Phosphorus, Nitrogen, Silicon and Carbon2017Ingår i: Frontiers in Marine Science, ISSN 2296-7745, Vol. 4, nr 27Artikel i tidskrift (Refereegranskat)
  • 262. Hankin, Barry
    et al.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Burgess, Chris
    Pers, Charlotta
    SMHI, Forskningsavdelningen, Hydrologi.
    Bielby, Sally
    Revilla-Romero, Beatriz
    Pope, Linda
    A New National Water Quality Model to Evaluate the Effectiveness of Catchment Management Measures in England2019Ingår i: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, nr 8, artikel-id 1612Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This investigation reports on a new national model to evaluate the effectiveness of catchment sensitive farming in England, and how pollution mitigation measures have improved water quality between 2006 and 2016. An adapted HYPE (HYdrological Predictions for the Environment) model was written to use accurate farm emissions data so that the pathway impact could be accounted for in the land phase of transport. Farm emissions were apportioned into different runoff fractions simulated in surface and soil layers, and travel time and losses were taken into account. These were derived from the regulator's catchment change matrix' and converted to monthly load time series, combined with extensive point source load datasets. Very large flow and water quality monitoring datasets were used to calibrate the model nationally for flow, nitrogen, phosphorus, suspended sediments and faecal indicator organisms. The model was simulated with and without estimated changes to farm emissions resulting from catchment measures, and spatial and temporal changes to water quality concentrations were then assessed.

  • 263. Hansen, A. L.
    et al.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Refsgaard, J. C.
    Karlsson, I. B.
    Simulation of nitrate reduction in groundwater - An upscaling approach from small catchments to the Baltic Sea basin2018Ingår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 111, s. 58-69Artikel i tidskrift (Refereegranskat)
  • 264.
    Hansson, Lars J.
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Hansson, Lars Johan
    SMHI.
    Craig, Sean F.
    Hughes, Roger N.
    Bishop, John D. D.
    Microscale genetic differentiation in a sessile invertebrate with cloned larvae: investigating the role of polyembryony2007Ingår i: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 153, nr 1, s. 71-82Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Microscale genetic differentiation of sessile organisms can arise from restricted dispersal of sexual propagules, leading to isolation by distance, or from localised cloning. Cyclostome bryozoans offer a possible combination of both: the localised transfer of spermatozoa between mates with limited dispersal of the resulting larvae, in association with the splitting of each sexually produced embryo into many clonal copies (polyembryony). We spatially sampled 157 colonies of Crisia denticulata from subtidal rock overhangs from one shore in Devon, England at a geographic scale of ca. 0.05 to 130 m plus a further 21 colonies from Pembrokeshire, Wales as an outgroup. Analysis of molecular variance (AMOVA) revealed that the majority (67%) of genetic variation was distributed among individuals within single rock overhangs, with only 16% of variation among different overhangs within each shore and 17% of variation between the ingroup and outgroup shores. Despite local genetic variation, pairwise genetic similarity analysed by spatial autocorrelation was greatest at the smallest inter-individual distance we tested (5 cm) and remained significant and positive across generally within-overhang comparisons (< 4 m). Spatial autocorrelation and AMOVA analyses both indicated that patches of C. denticulata located on different rock overhangs tended to be genetically distinct, with the switch from positive to negative autocorrelation, which is often considered to be the distance within which individuals reproduce with their close relatives or the radius of a patch, occurring at the 4-8 m distance class. Rerunning analyses with twenty data sets that only included one individual of each multilocus genotype (n = 97) or the single data set that contained just the unique genotypes (n = 67) revealed that the presence of repeat genotypes had an impact on genetic structuring (PhiPT values were reduced when shared genotypes were removed from the dataset) but that it was not great and only statistically evident at distances between individuals of 1-2 m. Comparisons to a further 20 randomisations of the data set that were performed irrespective of genotype (n = 97) suggested that this conclusion is not an artefact of reduced sample size. A resampling procedure using kinship coefficients, implemented by the software package GENCLONE gave broadly similar results but the greater statistical power allowed small but significant impacts of repeat genotypes on genetic structure to be also detected at 0.125-0.5 and 4-16 m. Although we predict that a proportion of the repeat multilocus genotypes are shared by chance, such generally within-overhang distances may represent a common distance of cloned larval dispersal. These results suggests that closely situated potential mates include a significant proportion of the available genetic diversity within a population, making it unlikely that, as previously hypothesised, the potential disadvantage of producing clonal broods through polyembryony is offset by genetic uniformity within the mating neighbourhood. We also report an error in the published primer note of Craig et al. (Mol Ecol Notes 1:281-282, 2001): loci Cd5 and Cd6 appear to be the same microsatellite.

  • 265.
    Hansson, Martin
    et al.
    SMHI, Samhälle och säkerhet.
    Andersson, Lars
    SMHI, Samhälle och säkerhet.
    Oxygen Survey in the Baltic Sea 2016 - Extent of Anoxia and Hypoxia, 1960-20162016Rapport (Övrigt vetenskapligt)
  • 266. Hansson, Martin
    et al.
    Håkansson, Bertil
    SMHI, Forskningsavdelningen, Oceanografi.
    The Baltic Algae Watch System - a remote sensing application for monitoring cyanobacterial blooms in the Baltic Sea2007Ingår i: Journal of Applied Remote Sensing, ISSN 1931-3195, E-ISSN 1931-3195, Vol. 1, artikel-id 011507Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nowcasting of harmful algal blooms is important both for the public and for environmental management purposes. In the Baltic Sea summer blooms of nitrogen-fixing cyanobacteria are regular phenomena but the past years intense and widespread blooms have caused major environmental concern due to its nuisance, increased nitrogen input and toxicity. The Swedish Meteorological and Hydrological Institute have developed a monitoring application that use satellite data to detect blooms and that assembles essential sources of information at one website. A supervised classifications algorithm has been applied to NOAA-AVHRR data during 1997-2006 and the dataset collected has been evaluated and analyzed. Subsequently, definitions of normalized bloom duration, extent and intensity have been developed to enable comparison between different years. Results suggest that the most intense blooms during 1997-2006 were recorded in 2006, while both 2005 and 2006 had the longest duration. The largest extent was noted in 1998. The experience from the 10 years of monitoring has shown that the combination of satellite imagery, observations, forecasts and tools assembled at one website, is a powerful nowcasting tool for monitoring and prediction of cyanobacterial blooms.

  • 267.
    Hansson, Martin
    et al.
    SMHI, Samhälle och säkerhet.
    Viktorsson, Lena
    SMHI, Samhälle och säkerhet.
    Andersson, Lars
    SMHI, Samhälle och säkerhet.
    Oxygen Survey in the Baltic Sea 2017 - Extent of Anoxia and Hypoxia, 1960-20172018Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En klimatologisk atlas över syresituationen i Östersjöns djupvatten publicerades 2011 i SMHIs Report Oceanography No 42. Sedan 2011 har årliga uppdateringar gjorts då kompletterande data från länder runt Östersjön har rapporerats till ICES. I denna rapport har resultaten från 2016 uppdaterats. De preliminära resultaten för 2017 baseras på data insamlade under Baltic International Acoustic Survey (BIAS) och nationell miljöövervakning med bidrag från Sverige, Finland och Polen.

    Förekomsten av hypoxi (syrebrist) och anoxi (helt syrefria förhållanden) under höstperioden, har undersökts i varje mätprofil. Djupet där hypoxi eller anoxi först påträffas i en profil har interpolerats mellan provtagningsstationer och kombinerats med en djupdatabas för beräkning av utbredning och volym av hypoxiska och anoxiska förhållanden. Resultaten har överförts till kartor och diagram för att visualisera syresituationen i Östersjöns djupvatten.

    Resultaten för 2016 och de preliminära resultaten för 2017 visar att de extremasyreförhållanden som observerats i Egentliga Östersjön fortsätter. Utbredningen av anoxi fortsätter att vara konstant förhöjd till nivåer som bara observerats i Östersjön enstaka år före 1999. Trots ett flertal inflöden under perioden 2014-2016 beräknas ungefär 18% av bottnarna i Egentliga Östersjön, Finska viken och Rigabukten vara påverkade av anoxiska förhållanden och omkring 28% av hypoxi under 2017. Inflödena 2014-2016 har minskat poolen av svavelväte så att den nästan helt försvunnit i Östra och Norra Gotlandsbassängen. Dock är syrgashalterna fortsatt noll eller mycket nära noll i djupvattnet och tecken på ökade halter av svavelväte har noterats under 2017.

  • 268.
    Hansson, Martin
    et al.
    SMHI, Samhälle och säkerhet.
    Viktorsson, Lena
    SMHI, Samhälle och säkerhet.
    Andersson, Lars
    SMHI, Samhälle och säkerhet.
    Oxygen Survey in the Baltic Sea 2018 - Extent of Anoxia and Hypoxia, 1960-20182018Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En klimatologisk atlas över syresituationen i Östersjöns djupvatten publicerades 2011 i SMHIs Report Oceanography No 42. Sedan 2011 har årliga uppdateringar gjorts då kompletterande data från länder runt Östersjön har rapporerats till ICES datacenter. I denna rapport har resultaten från 2017 uppdaterats och preliminära resultat för 2018 tagits fram. Resultaten för 2018 baseras på data insamlade under internationella fiskeriundersökningar, nationell miljöövervakning och forskningsprojekt med bidrag från Danmark, Estland, Lettland, Sverige, Finland, Ryssland och Polen. Förekomsten av hypoxi (syrebrist) och anoxi (helt syrefria förhållanden) under höstperioden, har undersökts i varje mätprofil. Djupet där hypoxi eller anoxi först påträffas i en profil har interpolerats mellan provtagningsstationer och kombinerats med en djupdatabas för beräkning av utbredning och volym av hypoxiska och anoxiska förhållanden. Resultaten har överförts till kartor och diagram för att visualisera syresituationen i Östersjöns djupvatten. Resultaten för 2017 och de preliminära resultaten för 2018 visar att de extrema syreförhållanden som observerats i Egentliga Östersjön, efter regimskiftet 1999, fortsätter. Utbredningen av anoxi fortsätter att vara konstant förhöjd till nivåer som bara observerats i Östersjön enstaka år före 1999. Trots ett flertal inflöden under perioden 2014-2016 beräknas ungefär 22% av bottnarna i Egentliga Östersjön, Finska viken och Rigabukten vara påverkade av anoxiska förhållanden och omkring 32% av hypoxi under 2018. De preliminära resultaten från 2018 indikerar att de anoxiska områdena är de största som har noterats under den analyserade perioden, som startar 1960. Mängden svavelväte, som på grund av inflödena 2014- 2016, helt försvann från Östra och Norra Gotlandsbassängerna, ökar åter i dessa bassängers djupvatten.

  • 269.
    Harlin, Joakim
    SMHI.
    DEVELOPMENT OF A PROCESS ORIENTED CALIBRATION SCHEME FOR THE HBV HYDROLOGICAL MODEL1991Ingår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 22, nr 1, s. 15-36Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A process oriented calibration scheme (POC), developed for the HBV hydrological model is presented. Twelve parameters were calibrated in two steps. Firstly, initial parameter estimates were made from recession analysis of observed runoff. Secondly, the parameters were calibrated individually in an iteration loop starting with the snow routine, over the soil routine and finally the runoff-response function. This was done by minimizing different objective functions for different parameters and only over subperiods where the parameters were active. Approximately three hundred and fifty objective function evaluations were needed to find the optimal parameter set, which resulted in a computer time of about 17 hours on a 386 processor PC for a ten-year calibration period. Experiments were also performed with fine tuning as well as direct search of the response surface, where the parameters were allowed to change simultaneously. A calibration period length of between two and six years was found sufficient to find optimal parameters in the test basins. The POC scheme yielded as good model performance as after a manual calibration.

  • 270.
    Harlin, Joakim
    SMHI.
    Hydrological modelling of extreme floods in Sweden1992Rapport (Övrigt vetenskapligt)
    Abstract [en]

    The Swedish guidelines for design flood determination are examined with emphasis on sensitivity analyses of modelling aspects. The research is mainly based on conceptual hydrological modelling with the HBV model. An automatic calibration methodology is presented and discussed. The influence of model calibration, model structure and climatic variability on the design flood simulation as well as the preset meteorological and hydrological conditions suggested in the guidelines are studied. The thesis also includes a discussion of the annual exceedance probability of the Swedish design floods by comparisons with observed extreme floods and frequency analyses.

    The design precipitation and snowpack magnitude are the most important rescriptions in the Swedish guidelines for design flood determination. Consequently, the regional design precipitation sequence and all suggested correction factors to the design rainfall sequence (area, altitude and season) are crucial. In application, the most important factors are: choice of  hydrological model, model calibration and selected climate period. These factors can lead to an uncertainty in the order of plus/minus 20 % on the design flood peak in catchments with good quality data and good model performance. In catchments with poor data quality, the uncertainty in design flood simulation will be larger. The corresponding uncertainty on reservoir water stage development will depend on local conditions.

  • 271.
    Harlin, Joakim
    SMHI.
    MODELING THE HYDROLOGICAL RESPONSE OF EXTREME FLOODS IN SWEDEN1992Ingår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 23, nr 4, s. 227-244Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hydrological models are today used for simulating extreme floods with the purpose of designing dams and spillways. In doing so, an extrapolation beyond the floods of the calibration period is made. This paper addresses this problem in connection to the HBV hydrological model. The model component describing flood dynamics, the runoff-response function, is studied. The methodology has been to calibrate different runoff-response functions over small to moderately large floods and to verify the performance over independent periods containing large experienced floods. Furthermore, the different model versions were run with extreme rainfall in order to generate design floods. It was found that the five-parameter response function of the original HBV model could be replaced by nonlinear functions including fewer parameters. However, it was difficult to select any response function formulation as significantly better than the others when extreme floods larger than those of the calibration period were simulated.

  • 272.
    Harlin, Joakim
    et al.
    SMHI.
    KUNG, CS
    PARAMETER UNCERTAINTY AND SIMULATION OF DESIGN FLOODS IN SWEDEN1992Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 137, nr 1-4, s. 209-230Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper examines the effects of parameter uncertainty on the simulation of recorded floods and design floods, using the HBV hydrological model. Two Swedish catchments with hydropower development were studied. A Monte Carlo procedure was used to generate parameter sets of different levels of uncertainty. The results showed that the most sensitive parameters in the calibration process were the snowfall correction factor and the recession parameters. Furthermore, when the model was extrapolated to simulate design flood and water stage hydrographs, the single most sensitive parameter was the highest recession coefficient. In addition, it was found that parameter uncertainty was associated with combinations of parameters rather than the absolute values of each.

  • 273.
    Harlin, Joakim
    et al.
    SMHI.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Sundby, Mikael
    SMHI.
    Brandesten, Claes-Olof
    Vattenfall Hydropower AB.
    Känslighetsanalys av Flödeskommitténs riktlinjer för dimensionering av hel älv1992Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    En känslighetsanalys av Flödeskommittens riktlinjer för beräkning av dimensionerande

    flöden tillämpade på flermagasinssystemet i Ljusnan redovisas. Simuleringarna har gjorts med hjälp av ett modell.system baserat på HBV-modellen, som kompletterats med regleringsstrategier. Det 14 560 km 2 stora avrinningsområdet delades in i 16 delområden. Vid tre kraftverksdammar studerades känsligheten hos de dimensionerande vattennivåerna med hänsyn tagen till ändringar i de föreskrivna riktlinjerna, regleringsstrategier

    och modellparametrar. Förändringar i den dimensionerande nederbörden, snömagasinet

    eller utskovskapaciteten hade betydande inverkan på högsta vattenståndet i alla tre

    magasinen. Ändringar i regleringsstrategierna hade mindre effekt. Den högsta recessionsparametern i HBV-modellen,

    Ko, hade stor inverkan på de dimensionerande vattennivåerna. Efter det att magasinet fyllts, syntes ett klart samband mellan högsta tillrinning och maximal vattennivå. Studien visar, att det är svårt att förutbestämma den integrerade effekten av extrem nederbörd, snösmältning, markfuktighetstillstånd och reglering i ett system.

  • 274. Hattermann, F. F.
    et al.
    Krysanova, V.
    Gosling, S. N.
    Dankers, R.
    Daggupati, P.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Floerke, M.
    Huang, S.
    Motovilov, Y.
    Buda, S.
    Yang, T.
    Mueller, C.
    Leng, G.
    Tang, Q.
    Portmann, F. T.
    Hagemann, S.
    Gerten, D.
    Wada, Y.
    Masaki, Y.
    Alemayehu, T.
    Satoh, Y.
    Samaniego, L.
    Cross-scale intercomparison of climate change impacts simulated by regional and global hydrological models in eleven large river basins2017Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, nr 3, s. 561-576Artikel i tidskrift (Refereegranskat)
  • 275. Hattermann, F. F.
    et al.
    Vetter, T.
    Breuer, L.
    Su, Buda
    Daggupati, P.
    Donnelly, Chantal
    SMHI, Forskningsavdelningen, Hydrologi.
    Fekete, B.
    Floerke, F.
    Gosling, S. N.
    Hoffmann, P.
    Liersch, S.
    Masaki, Y.
    Motovilov, Y.
    Mueller, C.
    Samaniego, L.
    Stacke, T.
    Wada, Y.
    Yang, T.
    Krysnaova, V.
    Sources of uncertainty in hydrological climate impact assessment: a cross-scale study2018Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, nr 1, artikel-id 015006Artikel i tidskrift (Refereegranskat)
  • 276. Hejzlar, J.
    et al.
    Anthony, S.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Behrendt, H.
    Bouraoui, F.
    Grizzetti, B.
    Groenendijk, P.
    Jeuken, M. H. J. L.
    Johnsson, H.
    Lo Porto, A.
    Kronvang, B.
    Panagopoulos, Y.
    Siderius, C.
    Silgram, M.
    Venohr, M.
    Zaloudik, J.
    Nitrogen and phosphorus retention in surface waters: an inter-comparison of predictions by catchment models of different complexity2009Ingår i: Journal of Environmental Monitoring, ISSN 1464-0325, E-ISSN 1464-0333, Vol. 11, nr 3, s. 584-593Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nitrogen and phosphorus retention estimates in streams and standing water bodies were compared for four European catchments by a series of catchment-scale modelling tools of different complexity, ranging from a simple, equilibrium input-output type to dynamic, physical-based models: source apportionment, MONERIS, EveNFlow, TRK, SWAT, and NL-CAT. The four catchments represent diverse climate, hydrology, and nutrient loads from diffuse and point sources in Norway, the UK, Italy, and the Czech Republic. The models' retention values varied largely, with tendencies towards higher scatters for phosphorus than for nitrogen, and for catchments with lakes (Vansjo-Hobol, Z. elivka) compared to mostly or entirely lakeless catchments (Ouse or Enza, respectively). A comparison of retention values with the size of nutrient sources showed that the modelled nutrient export from diffuse sources was directly proportional to retention estimates, hence implying that the uncertainty in quantification of diffuse catchment sources of nutrients was also related to the uncertainty in nutrient retention determination. This study demonstrates that realistic modelling of nutrient export from large catchments is very difficult without a certain level of measured data. In particular, even complex process oriented models require information on the retention capabilities of water bodies within the receiving surface water system and on the nutrient export from micro-catchments representing the major types of diffuse sources to surface waters.

  • 277. Hense, Inga
    et al.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Sonntag, Sebastian
    Projected climate change impact on Baltic Sea cyanobacteria Climate change impact on cyanobacteria2013Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 119, nr 2, s. 391-406Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Compared to other phytoplankton groups, nitrogen-fixing cyanobacteria generally prefer high water temperatures for growth and are therefore expected to benefit from global warming. We use a coupled biological-physical model with an advanced cyanobacteria life cycle model to compare the abundance of cyanobacteria in the Baltic Sea during two different time periods (1969-1998; 2069-2098). For the latter, we find prolonged growth and a more than twofold increase in the climatologically (30 years) averaged cyanobacteria biomass and nitrogen fixation. Additional sensitivity experiments indicate that the biological-physical feedback mechanism through light absorption becomes more important with global warming. In general, we find a nonlinear response of cyanobacteria to changes in the atmospheric forcing fields as a result of life-cycle related feedback mechanisms. Overall, the sensitivity of the cyanobacteria-driven system suggests that biological-physical and life-cycle related feedback mechanisms are important and must therefore be included in future projection studies.

  • 278.
    Hieronymus, Jenny
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Hieronymus, Magnus
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Saraiva, Sofia
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Causes of simulated long-term changes in phytoplankton biomass in the Baltic proper: a wavelet analysis2018Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 15, nr 16, s. 5113-5129Artikel i tidskrift (Refereegranskat)
  • 279.
    Hieronymus, Magnus
    SMHI, Forskningsavdelningen, Oceanografi.
    An update on the thermosteric sea level rise commitment to global warming2019Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, nr 5, artikel-id 054018Artikel i tidskrift (Refereegranskat)
  • 280.
    Hieronymus, Magnus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    The effects of mean sea level rise and strengthened winds on extreme sea levels in the Baltic Sea2018Ingår i: Theoretical and Applied Mechanics Letters, ISSN 2095-0349, Vol. 8, nr 6, s. 366-371Artikel i tidskrift (Refereegranskat)
  • 281.
    Hieronymus, Magnus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Hieronymus, Jenny
    SMHI, Forskningsavdelningen, Oceanografi.
    Arneborg, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Sea level modelling in the Baltic and the North Sea: The respective role of different parts of the forcing2017Ingår i: Ocean Modelling, ISSN 1463-5003, E-ISSN 1463-5011, Vol. 118, s. 59-72Artikel i tidskrift (Refereegranskat)
  • 282.
    Hieronymus, Magnus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Hieronymus, Jenny
    SMHI, Forskningsavdelningen, Oceanografi.
    Hieronymus, Fredrik
    On the Application of Machine Learning Techniques to Regression Problems in Sea Level Studies2019Ingår i: Journal of Atmospheric and Oceanic Technology, ISSN 0739-0572, E-ISSN 1520-0426, Vol. 36, nr 9, s. 1889-1902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Long sea level records with high temporal resolution are of paramount importance for future coastal protection and adaptation plans. Here we discuss the application of machine learning techniques to some regression problems commonly encountered when analyzing such time series. The performance of artificial neural networks is compared with that of multiple linear regression models on sea level data from the Swedish coast. The neural networks are found to be superior when local sea level forcing is used together with remote sea level forcing and meteorological forcing, whereas the linear models and the neural networks show similar performance when local sea level forcing is excluded. The overall performance of the machine learning algorithms is good, often surpassing that of the much more computationally costly numerical ocean models used at our institute.

  • 283.
    Hieronymus, Magnus
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Nycander, Jonas
    Nilsson, Johan
    Doos, Kristofer
    Hallberg, Robert
    Oceanic Overturning and Heat Transport: The Role of Background Diffusivity2019Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 32, nr 3, s. 701-716Artikel i tidskrift (Refereegranskat)
  • 284. Hoeltinger, Stefan
    et al.
    Mikovits, Christian
    Schmidt, Johannes
    Baumgartner, Johann
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Wetterlund, Elisabeth
    The impact of climatic extreme events on the feasibility of fully renewable power systems: A case study for Sweden2019Ingår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 178, s. 695-713Artikel i tidskrift (Refereegranskat)
  • 285. Ho-Hagemann, Ha Thi Minh
    et al.
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Rockel, Burkhardt
    Zahn, Matthias
    Geyer, Beate
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Effects of air-sea coupling over the North Sea and the Baltic Sea on simulated summer precipitation over Central Europe2017Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 49, nr 11-12, s. 3851-3876Artikel i tidskrift (Refereegranskat)
  • 286. Hojberg, Anker Lajer
    et al.
    Hansen, Anne Lausten
    Wachniew, Przemyslaw
    Zurek, Anna J.
    Virtanen, Seija
    Arustiene, Jurga
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Rankinen, Katri
    Refsgaard, Jens Christian
    Review and assessment of nitrate reduction in groundwater in the Baltic Sea Basin2017Ingår i: JOURNAL OF HYDROLOGY-REGIONAL STUDIES, ISSN 2214-5818, Vol. 12, s. 50-68Artikel i tidskrift (Refereegranskat)
  • 287. Holopainen, Reetta
    et al.
    Lehtiniemi, Maiju
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Albertsson, Jan
    Gorokhova, Elena
    Kotta, Jonne
    Viitasalo, Markku
    Impacts of changing climate on the non-indigenous invertebrates in the northern Baltic Sea by end of the twenty-first century2016Ingår i: Biological Invasions, ISSN 1387-3547, E-ISSN 1573-1464, Vol. 18, nr 10, s. 3015-3032Artikel i tidskrift (Refereegranskat)
  • 288. Hood, Lon
    et al.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, Thomas
    Bal, Sourabh
    Cubasch, Ulrich
    The Surface Climate Response to 11-Yr Solar Forcing during Northern Winter: Observational Analyses and Comparisons with GCM Simulations2013Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 26, nr 19, s. 7489-7506Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The surface climate response to 11-yr solar forcing during northern winter is first reestimated by applying a multiple linear regression (MLR) statistical model to Hadley Centre sea level pressure (SLP) and sea surface temperature (SST) data over the 1880-2009 period. In addition to a significant positive SLP response in the North Pacific found in previous studies, a positive SST response is obtained across the midlatitude North Pacific. Negative but insignificant SLP responses are obtained in the Arctic. The derived SLP response at zero lag therefore resembles a positive phase of the Arctic Oscillation (AO). Evaluation of the SLP and SST responses as a function of phase lag indicates that the response evolves from a negative AO-like mode a few years before solar maximum to a positive AO-like mode at and following solar maximum. For comparison, a similar MLR analysis is applied to model SLP and SST data from a series of simulations using an atmosphere-ocean general circulation model with a well-resolved stratosphere. The simulations differed only in the assumed solar cycle variation of stratospheric ozone. It is found that the simulation that assumed an ozone variation estimated from satellite data produces solar SLP and SST responses that are most consistent with the observational results, especially during a selected centennial period. In particular, a positive SLP response anomaly is obtained in the northeastern Pacific and a corresponding positive SST response anomaly extends across the midlatitude North Pacific. The model response versus phase lag also evolves from a mainly negative AO-like response before solar maximum to a mainly positive AO response at and following solar maximum.

  • 289.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Fransner, Filippa
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Pemberton, Per
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Ljungemyr, Patrik
    SMHI, Samhälle och säkerhet.
    Nygren, Petter
    SMHI, Samhälle och säkerhet.
    Falahat, Saeed
    SMHI, Samhälle och säkerhet.
    Nord, Adam
    SMHI, Samhälle och säkerhet.
    Jönsson, Anette
    SMHI, Samhälle och säkerhet.
    Lake, Irene
    SMHI, Samhälle och säkerhet. SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doos, Kristofer
    Hieronymus, Magnus
    SMHI, Forskningsavdelningen, Oceanografi.
    Dietze, Heiner
    Loeptien, Ulrike
    Kuznetsov, Ivan
    Westerlund, Antti
    Tuomi, Laura
    Haapala, Jari
    Nemo-Nordic 1.0: a NEMO-based ocean model for the Baltic and North seas - research and operational applications2019Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, nr 1, s. 363-386Artikel i tidskrift (Refereegranskat)
  • 290.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Löptien, Ulrike
    SMHI, Forskningsavdelningen, Oceanografi.
    Dietze, Heiner
    Kuznetsov, Ivan
    SMHI, Forskningsavdelningen, Oceanografi.
    Influence of sea level rise on the dynamics of salt inflows in the Baltic Sea2015Ingår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 120, nr 10, s. 6653-6668Artikel i tidskrift (Refereegranskat)
    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.

  • 291.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Basu, Chandan
    Dietze, Heiner
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Freshwater outflow of the Baltic Sea and transport in the Norwegian current: A statistical correlation analysis based on a numerical experiment2013Ingår i: Continental Shelf Research, ISSN 0278-4343, E-ISSN 1873-6955, Vol. 64, s. 1-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Based on the results of a numerical ocean model, we investigate statistical correlations between wind forcing, surface salinity and freshwater transport out of the Baltic Sea on one hand, and Norwegian coastal current freshwater transport on the other hand. These correlations can be explained in terms of physics and reveal how the two freshwater transports are linked with wind forcing, although this information proves to be non-sufficient when it comes to the dynamics of the Norwegian coastal current. Based on statistical correlations, the Baltic Sea freshwater transport signal is reconstructed and shows a good correlation but a poor variability when compared with the measured signal, at least when data filtered on a two-daily time scale is used. A better variability coherence is reached when data filtered on a weekly or monthly time scale is used. In the latest case, a high degree of precision is reached for the reconstructed signal. Using the same kind of methods for the case of the Norwegian coastal current, the negative peaks of the freshwater transport signal can be reconstructed based on wind data only, but the positive peaks are under-represented although some of them exist mostly because the meridional wind forcing along the Norwegian coast is taken into account. Adding Norwegian coastal salinity data helps improving the reconstruction of the positive peaks, but a major improvement is reached when adding non-linear terms in the statistical reconstruction. All coefficients used to re-construct both freshwater transport signals are provided for use in European Shelf or climate modeling configurations. (c) 2013 Elsevier Ltd. All rights reserved.

  • 292.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Pemberton, Per
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Sensitivity of the overturning circulation of the Baltic Sea to climate change, a numerical experiment2018Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 50, nr 3-4, s. 1425-1437Artikel i tidskrift (Refereegranskat)
  • 293.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Effect of climate change on the thermal stratification of the baltic sea: a sensitivity experiment2012Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, nr 9-10, s. 1703-1713Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The evolution in time of the thermal vertical stratification of the Baltic Sea in future climate is studied using a 3D ocean model. Comparing periods at the end of the twentieth and twenty first centuries we found a strong increase in stratification at the bottom of the mixed layer in the northern Baltic Sea. In order to understand the causes of this increase, a sensitivity analysis is performed. We found that the increased vertical stratification is explained by a major change in re-stratification during spring solely caused by the increase of the mean temperature. As in present climate winter temperatures in the Baltic are often below the temperature of maximum density, warming causes thermal convection. Re-stratification during the beginning of spring is then triggered by the spreading of freshwater. This process is believed to be important for the onset of the spring bloom. In future climate, temperatures are expected to be usually higher than the temperature of maximum density and thermally induced stratification will start without prior thermal convection. Thus, freshwater controlled re-stratification during spring is not an important process anymore. We employed a simple box model and used sensitivity experiments with the 3D ocean model to delineate the processes involved and to quantify the impact of changing freshwater supply on the thermal stratification in the Baltic Sea. It is suggested that these stratification changes may have an important impact on vertical nutrient fluxes and the intensity of the spring bloom in future climate of the Baltic Sea.

  • 294.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Freshwater fluxes in the Baltic Sea: A model study2010Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 115, artikel-id C08028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The dynamics of "juvenile" freshwater, which is released during spring into the Baltic proper, is studied using a numerical three-dimensional circulation model. Two methods are used. First, freshwater heights are calculated using simulated salinity fields, and their seasonal variability is analyzed. When compared to climatological observations, the model represents the seasonal variability of freshwater heights well. However, the method does not allow a proper study of the dynamics of juvenile freshwater fluxes. Consequently, a second method is used where a passive tracer, which marks freshwater, is utilized. This method provides a better description of the seasonal spreading of juvenile freshwater in the Baltic proper, although further investigations are still necessary to trace juvenile freshwater. The results from this second method show that juvenile freshwater does not reach the center of the Baltic proper before late summer. During one season, only a small amount of juvenile freshwater may reach the entrance of the Baltic Sea. The increased vertical stratification generated by the arrival of juvenile freshwater and the subsequent baroclinic adjustment may trigger the onset of the spring bloom in accordance to earlier suggestions. Further, the seasonal cycle and inter-annual variability of the freshwater outflow from the Baltic Sea are studied. Seasonal changes of the freshwater outflow are closely connected with that of the zonal wind, although the annual mean outflow is given by the total runoff into the Baltic Sea. Thus, the inter-annual variability of the seasonal freshwater outflow maximum is highly correlated with the North Atlantic Oscillation.

  • 295. Hrachowitz, M.
    et al.
    Savenije, H. H. G.
    Bloeschl, G.
    McDonnell, J. J.
    Sivapalan, M.
    Pomeroy, J. W.
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Blume, T.
    Clark, M. P.
    Ehret, U.
    Fenicia, F.
    Freer, J. E.
    Gelfan, A.
    Gupta, H. V.
    Hughes, D. A.
    Hut, R. W.
    Montanari, A.
    Pande, S.
    Tetzlaff, D.
    Troch, P. A.
    Uhlenbrook, S.
    Wagener, T.
    Winsemius, H. C.
    Woods, R. A.
    Zehe, E.
    Cudennec, C.
    A decade of Predictions in Ungauged Basins (PUB)a review2013Ingår i: Hydrological Sciences Journal, ISSN 0262-6667, E-ISSN 2150-3435, Vol. 58, nr 6, s. 1198-1255Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Prediction in Ungauged Basins (PUB) initiative of the International Association of Hydrological Sciences (IAHS), launched in 2003 and concluded by the PUB Symposium 2012 held in Delft (23-25 October 2012), set out to shift the scientific culture of hydrology towards improved scientific understanding of hydrological processes, as well as associated uncertainties and the development of models with increasing realism and predictive power. This paper reviews the work that has been done under the six science themes of the PUB Decade and outlines the challenges ahead for the hydrological sciences community.

  • 296. Hu, Yue O. O.
    et al.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Charvet, Sophie
    Andersson, Anders F.
    Diversity of Pico- to Mesoplankton along the 2000 km Salinity Gradient of the Baltic Sea2016Ingår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, artikel-id 679Artikel i tidskrift (Refereegranskat)
  • 297. Huang, Shaochun
    et al.
    Kumar, Rohini
    Floerke, Martina
    Yang, Tao
    Hundecha, Yeshewatesfa
    SMHI, Forskningsavdelningen, Hydrologi.
    Kraft, Philipp
    Gao, Chao
    Gelfan, Alexander
    Liersch, Stefan
    Lobanova, Anastasia
    Strauch, Michael
    van Ogtrop, Floris
    Reinhardt, Julia
    Haberlandt, Uwe
    Krysanova, Valentina
    Evaluation of an ensemble of regional hydrological models in 12 large-scale river basins worldwide2017Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, nr 3, s. 381-397Artikel i tidskrift (Refereegranskat)
  • 298. Huang, Shaochun
    et al.
    Kumar, Rohini
    Floerke, Martina
    Yang, Tao
    Hundecha, Yeshewatesfa
    SMHI, Forskningsavdelningen, Hydrologi.
    Kraft, Philipp
    Gao, Chao
    Gelfan, Alexander
    Liersch, Stefan
    Lobanova, Anastasia
    Strauch, Michael
    van Ogtrop, Floris
    Reinhardt, Julia
    Haberlandt, Uwe
    Krysanova, Valentina
    Evaluation of an ensemble of regional hydrological models in 12 large-scale river basins worldwide (vol 141, pg 381, 2017)2017Ingår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 141, nr 3, s. 399-400Artikel i tidskrift (Refereegranskat)
  • 299. Hughes, Denis A.
    et al.
    Andersson, Lotta
    SMHI, Samhälle och säkerhet.
    Wilk, Julie
    Savenije, Hubert H. G.
    Regional calibration of the Pitman model for the Okavango River2006Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 331, nr 1-2, s. 30-42Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper reports on the application of a monthly rainfall-runoff model for the Okavango River Basin. Streamflow is mainly generated in Angola where the Cuito and Cubango rivers arise. They then join and cross the Namibia/Angola border, flowing into the Okavango wetland in Botswana. The model is a modified version of the Pitman model, including more explicit ground and surface water interactions. Significant limitations in access to climatological data, and lack of sufficiently long records of observed flow for the eastern sub-basins represent great challenges to model calibration. The majority of the runoff is generated in the wetter headwater tributaries, while the lower sub-basins are dominated by channel loss processes with very little incremental flow contributions, even during wet years. The western tributaries show significantly higher seasonal variation in flow, compared to the baseflow dominated eastern tributaries: observations that are consistent with their geological differences. The basin was sub-divided into 24 sub-basins, of which 18 have gauging stations at their outlet. Satisfactory simulations were achieved with sub-basin parameter value differences that correspond to the spatial variability in basin physiographic characteristics. The limited length of historical rainfall and river discharge data over Angola precluded the use of a split sample calibration/validation test. However, satellite generated rainfall data, revised to reflect the same frequency characteristics as the historical rainfall data, were used to validate the model against the available downstream flow data during the 1990s. The overall conclusion is that the model, in spite of the limited data access, adequately represents the hydrological response of the basin and that it can be used to assess the impact of future development scenarios. (c) 2006 Elsevier B.V. All rights reserved.

  • 300. Huisman, J. A.
    et al.
    Breuer, L.
    Bormann, H.
    Bronstert, A.
    Croke, B. F. W.
    Frede, H. -G
    Graeff, T.
    Hubrechts, L.
    Jakeman, A. J.
    Kite, G.
    Lanini, J.
    Leavesley, G.
    Lettenmaier, D. P.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Seibert, J.
    Sivapalan, M.
    Viney, N. R.
    Willems, P.
    Assessing the impact of land use change on hydrology by ensemble modeling (LUCHEM) III: Scenario analysis2009Ingår i: Advances in Water Resources, ISSN 0309-1708, E-ISSN 1872-9657, Vol. 32, nr 2, s. 159-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An ensemble of 10 hydrological models was applied to the same set of land use change scenarios. There was general agreement about the direction of changes in the mean annual discharge and 90% discharge percentile predicted by the ensemble members, although a considerable range in the magnitude of predictions for the scenarios and catchments under consideration was obvious. Differences in the magnitude of the increase were attributed to the different mean annual actual evapotranspiration rates for each land use type. The ensemble of model runs was further analyzed with deterministic and probabilistic ensemble methods. The deterministic ensemble method based on a trimmed mean resulted in a single somewhat more reliable scenario prediction. The probabilistic reliability ensemble averaging (REA) method allowed a quantification of the model structure uncertainty in the scenario predictions. It was concluded that the use of a model ensemble has greatly increased our confidence in the reliability of the model predictions. (C) 2008 Elsevier Ltd. All rights reserved.

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