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  • 101. Puillat, I.
    et al.
    Farcy, P.
    Durand, D.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Petihakis, G.
    Seppala, J.
    Sparnocchia, S.
    Progress in marine science supported by European joint coastal observation systems: The JERICO-RI research infrastructure2016Inngår i: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 162, s. 1-3Artikkel i tidsskrift (Fagfellevurdert)
  • 102.
    Wåhlström, Irene
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Pemberton, Per
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Impact of increasing inflow of warm Atlantic water on the sea-air exchange of carbon dioxide and methane in the Laptev Sea2016Inngår i: Journal of Geophysical Research - Biogeosciences, ISSN 2169-8953, E-ISSN 2169-8961, Vol. 121, nr 7, s. 1867-1883Artikkel i tidsskrift (Fagfellevurdert)
  • 103.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Invasive species in the Baltic Sea A model study of plankton transport2016Rapport (Annet vitenskapelig)
    Abstract [en]

    In this report, an ensemble of releases of passive particles at locations close to some

    selected ports around the Baltic Sea and Kattegat are modelled. The particles are

    transported with the currents. Maps of particle densities at 2, 4, 8, 16, 32 and 52

    weeks after the release are presented.

    The results indicate that many basins are narrow enough for the particles to cross

    from shore to shore within two weeks, e.g., in the Kattegat, Gulf of Finland and

    Kvarken. The results also show an asymmetry in the transport between different

    locations, which means that particles released from one location to another require

    substantially more time to reach the other location, if at all, than particles going

    in the opposite direction. Some potential barriers to transport are identified and

    discussed.

  • 104. Enmar, Linda
    et al.
    Lake, Irene
    SMHI, Forskningsavdelningen, Oceanografi.
    Lundberg, Peter
    Sigray, Peter
    A note on ADCP-based indirect observations of turbulence2016Inngår i: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 21, nr 1-2, s. 44-52Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 70-day data set from bottom-mounted ADCPs on the two sides of the Faroe-Bank Channel was analysed using the recorded flow variance and echo intensity in the deeper reaches of the passage as proxies for turbulence. A consistent picture emerged, not least since the data losses (which were ascribed to turbulence-induced activation of the fish-elimination option in the ADCP software) could be shown to co-vary with the internal M-2 tide affecting the vertical shear, which in turn proved to be correlated with the flow variance.

  • 105. 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 Sea2016Inngår i: Frontiers in Microbiology, ISSN 1664-302X, E-ISSN 1664-302X, Vol. 7, artikkel-id 679Artikkel i tidsskrift (Fagfellevurdert)
  • 106.
    Kuznetsov, Ivan
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Model study on the variability of ecosystem parameters in the Skagerrak-Kattegat area, effect of load reduction in the North Sea and possible effect of BSAP on Skagerrak-Kattegat area2016Rapport (Annet vitenskapelig)
    Abstract [en]

    Newly developed ecosystem model NEMO-Nordic-SCOBI was applied to Skagerrak - Kattegat area to investigate the variability of some indicators of the ecosystem. Also, two sensitivity runs were performed to investigate possible effect of the Baltic Sea Action Plan (BSAP) and a river loads reduction scenario on the Skagerrak - Kattegat area. The performed investigation could be used “to provide a basis to assist with the interpretation of measurement data before the Intermediate Assessments Eutrophication status assessment”. Comparison of simulation results with observations indicates acceptable model performance. Modeled sea surface salinity, temperature and dissolved inorganic phosphate (DIP) are in good agreement with observations. At the same time, the model has a bias in certain areas of the investigated region for dissolved inorganic nitrogen (DIN) and dissolved silicate during the winter season. However, the model in its current state shows good enough results for the performed investigation. Results of the two sensitivity studies show a decrease of sea surface nutrients concentrations during winter period in both regions. In the Skagerrak area the decrease is due to reduction in river nutrient loads in North Sea. In the Kattegat area there is a decrease of dissolved phosphate due to the implementation of BSAP. At the same time, in both scenarios, no significant changes were obtained for near bottom oxygen or surface layer Chl-a.

  • 107.
    Andersson, Helén
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Eriksson Bram, Lena
    SMHI, Samhälle och säkerhet.
    Hjerdt, Niclas
    SMHI, Samhälle och säkerhet.
    Lindström, Göran
    SMHI, Forskningsavdelningen, Hydrologi.
    Löptien, Ulrike
    SMHI, Forskningsavdelningen, Oceanografi.
    Strömqvist, Johan
    SMHI, Forskningsavdelningen, Hydrologi.
    Översikt av beräkningsmodeller för bedömning av fiskodlingars näringsämnesbelastning på sjöar, vattendrag, magasin och kustvatten2016Rapport (Annet vitenskapelig)
    Abstract [sv]

    Den här rapporten är en kunskapssammanställning som utförts av SMHI på uppdrag av Havs- och Vattenmyndigheten. Den utgör inte något ställningstagande från Havs- och vattenmyndighetens sida. Rapporten försöker att sammanfatta den problematik som associeras med näringsämnesbelastningar från fiskodlingar i öppna kassar, vilka typer av beräkningar som kan behöva göras för att få en uppfattning om hur dessa kan påverka miljön samt några olika typer av modeller för detta ändamål.

    Fisk-, alg- och skaldjursodling är en växande industri runt om i världen som kan ge såväl näringsrik och hälsosam mat som arbetstillfällen. En nackdel med framförallt fiskodling i öppna kassar är att den kan innebära en påfrestning för vattenmiljön. De näringsämnen som ofta släpps ut från odlingen kan bidra till den övergödningsproblematik som redan finns i många sjöar och havsområden. Det är därför av största vikt att få en god uppskattning av den förväntade storleken på utsläppen förknippade med en öppen odling samt hur de kan tänkas förändra vattenkvaliteten på odlingsplatsen och dess närhet. Beräkningsmodeller kan vara till god hjälp vid bedömningen.

    Fiskar utsöndrar lösta näringsämnen och från odlingskassarna faller det också ut partikulärt organiskt material i form av fekalier och oätet foder. Storleken på näringsämneskällorna behöver beräknas och det finns modeller av olika komplexitet för att uppskatta detta. Storleken på det partikulära avfallet är viktigt dels för att det bidrarmed näringsämnen till vattnet och dels för att det kan ge upphov till ansamlingar av organiskt material på bottnen. När det organiska materialet bryts ner förbrukas syre och om ansamlingarna blir omfattande finns en risk för att det uppstår syrebrist vid bottnen. Om svavelväte bildas kan det orsaka skador på såväl den odlade fisken som det lokala ekosystemet. Odlingen kan också bidra till en försämrad vattenkvalitet i sin omgivning genom att tillgången av lösta näringsämnen blir större och därmed ge en ökad algproduktion. Den ökade algproduktionen skall i sin tur brytas ner och kan i förlängningen bidra till syrebristproblematiken.

    Det finns ett antal modeller som är specifikt utvecklade för fiskodlingar i öppna kassar och de tar i olika hög grad upp den beskrivna problematiken. Rapporten innehåller detaljerade genomgångar av några av modeller för att visa på styrkor och svagheter kring olika angreppsätt. Den innehåller också sammanfattningar av några vanligt förekommande modeller som använts internationellt vid bedömning av fiskodlingars miljöpåverkan. För att minska den negativa påverkan på vattenmiljön från har det också utvecklats recirkulerande system för odling. Rapporten tar inte upp belastning från den typen av fiskodlingar. Om utsläppen från ett sådant system är känt kan dock vattenkvalitetsmodeller användas för att se effekten av utsläpp från en punktkälla.

    Rapporten sammanfattar ett antal vattenkvalitetsmodeller för sjöar, vattendrag, kust och hav. En vattenkvalitetsmodell behöver inte nödvändigtvis vara utvecklad för att beskriva konsekvenser av fiskodlingar men bör kunna hantera frågeställningar som uppkommer vid bedömningar av övergödningsrisk vid utsläpp från en punktkälla. Den behöver därför kunna simulera parametrar såsom förändringen av näringsämneskoncentrationer, primärproduktion, siktdjup och syrgashalter på olika nivåer i vattenmassan. Modeller för den här typen av uppskattningar finns också i olika komplexitetsgrad och för olika skalor i tid och rum.

    Vid modellering är en god tillgång till observationer en förutsättning för pålitliga modellresultat och behövs såväl för att driva och kalibrera modellen som för validering av modellresultaten. Det är viktigt att tillgängliga data håller god kvalitet. En noggrann analys och beskrivning av den tillgängliga databasen hjälper därmed till att bedöma tillförlitligheten av modellsimuleringarna.

  • 108.
    Koenigk, Torben
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Caian, Mihaela
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Nikulin, Grigory
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Regional Arctic sea ice variations as predictor for winter climate conditions2016Inngår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 46, nr 1-2, s. 317-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seasonal prediction skill of winter mid and high northern latitudes climate from sea ice variations in eight different Arctic regions is analyzed using detrended ERA-interim data and satellite sea ice data for the period 1980-2013. We find significant correlations between ice areas in both September and November and winter sea level pressure, air temperature and precipitation. The prediction skill is improved when using November sea ice conditions as predictor compared to September. This is particularly true for predicting winter NAO-like patterns and blocking situations in the Euro-Atlantic area. We find that sea ice variations in Barents Sea seem to be most important for the sign of the following winter NAO-negative after low ice-but amplitude and extension of the patterns are modulated by Greenland and Labrador Seas ice areas. November ice variability in the Greenland Sea provides the best prediction skill for central and western European temperature and ice variations in the Laptev/East Siberian Seas have the largest impact on the blocking number in the Euro-Atlantic region. Over North America, prediction skill is largest using September ice areas from the Pacific Arctic sector as predictor. Composite analyses of high and low regional autumn ice conditions reveal that the atmospheric response is not entirely linear suggesting changing predictive skill dependent on sign and amplitude of the anomaly. The results confirm the importance of realistic sea ice initial conditions for seasonal forecasts. However, correlations do seldom exceed 0.6 indicating that Arctic sea ice variations can only explain a part of winter climate variations in northern mid and high latitudes.

  • 109. Fransner, Filippa
    et al.
    Nycander, Jonas
    Morth, Carl-Magnus
    Humborg, Christoph
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Gustafsson, Erik
    Deutsch, Barbara
    Tracing terrestrial DOC in the Baltic SeaA 3-D model study2016Inngår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 30, nr 2, s. 134-148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The fate of terrestrial organic matter brought to the coastal seas by rivers and its role in the global carbon cycle are still not very well known. Here the degradation rate of terrestrial dissolved organic carbon (DOCter) is studied in the Baltic Sea, a subarctic semienclosed sea, by releasing it as a tracer in a 3-D circulation model and applying linear decay constants. A good agreement with available observational data is obtained by parameterizing the degradation in two rather different ways: one by applying a decay time on the order of 10years to the whole pool of DOCter and one by dividing the DOCter into onerefractory pool and one pool subject to a decay time on the order of 1year. The choice ofparameterization has asignificant effect on where in the Baltic Sea the removal takes place, which can be of importance whenmodeling the full carbon cycle and the CO2 exchange with the atmosphere. In both cases the biogeochemical decayoperates on time scales less than the water residence time. Therefore, only a minor fraction of the DOCter reaches the North Sea, whereas approximately 80% is removed by internal sinks within the Baltic Sea. This further implies that DOCter mineralization is an important link in land-sea-atmosphere cycling of carbon in coastal and shelf seas that are heavily influenced by riverine DOC.

  • 110.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Nilsson, J.
    The response of the central Arctic Ocean stratification to freshwater perturbations2016Inngår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 121, nr 1, s. 792-817Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Using a state-of-the-art coupled ice-ocean-circulation model, we perform a number of sensitivity experiments to examine how the central Arctic Ocean stratification responds to changes in river runoff and precipitation. The simulations yield marked changes in the cold halocline and the Arctic Atlantic layer. Increased precipitation yields a warming of the Atlantic layer, which primarily is an advective signal, propagated through the St. Anna Trough, reflecting air-sea heat flux changes over the Barents Sea. As the freshwater supply is increased, the anticyclonic Beaufort Gyre is weakened and a greater proportion of the Arctic Ocean freshwater is exported via the Fram Strait, with nearly compensating export decreases through the Canadian Arctic Archipelago. The corresponding reorganization of the freshwater pool appears to be controlled by advective processes, rather than by the local changes in the surface freshwater flux. A simple conceptual model of the Arctic Ocean, based on a geostrophically controlled discharge of the low-salinity water, is introduced and compared with the simulations. Key predictions of the conceptual model are that the halocline depth should decrease with increasing freshwater input and that the Arctic Ocean freshwater storage should increase proportionally to the square root of the freshwater input, which are in broad qualitative agreement with the sensitivity experiments. However, the model-simulated rate of increase of the freshwater storage is weaker, indicating that effects related to wind forcing and rerouting of the freshwater-transport pathways play an important role for the dynamics of the Arctic Ocean freshwater storage.

  • 111.
    Axell, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Application of 3-D ensemble variational data assimilation to a Baltic Sea reanalysis 1989-20132016Inngår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 68, artikkel-id 24220Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 3-D ensemble variational (3DEnVar) data assimilation method has been implemented and tested for oceanographic data assimilation of sea surface temperature (SST), sea surface salinity (SSS), sea ice concentration (SIC), and salinity and temperature profiles. To damp spurious long-range correlations in the ensemble statistics, horizontal and vertical localisation was implemented using empirical orthogonal functions. The results show that the 3DEnVar method is indeed possible to use in oceanographic data assimilation. So far, only a seasonally dependent ensemble has been used, based on historical model simulations. Near-surface experiments showed that the ensemble statistics gave inhomogeneous and anisotropic horizontal structure functions, and assimilation of real SST and SIC fields gave smooth, realistic increment fields. The implementation was multivariate, and results showed that the cross-correlations between variables work in an intuitive way, for example, decreasing SST where SIC was increased and vice versa. The profile data assimilation also gave good results. The results from a 25-year reanalysis showed that the vertical salinity and temperature structure were significantly improved, compared to both dependent and independent data.

  • 112.
    Eilola, Kari
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Almroth-Rosell, Elin
    SMHI, Forskningsavdelningen, Oceanografi.
    Edman, Moa
    SMHI, Forskningsavdelningen, Oceanografi.
    Eremina, Tatjana 
    Russian State Hydrometeorological University, Sankt-Petersburg, Russia.
    Larsen, Janus
    Aarhus University, Roskilde, Denmark.
    Janas, Urszula 
    Institute of Oceanography, Gdansk University, Poland.
    Timmermann, Karen 
    Aarhus University, Roskilde, Denmark.
    Tedesco, Letizia 
    Finnish Environment Institute, Helsinki, Finland.
    Voloshchuk, Ekaterina 
    Russian State Hydrometeorological University, Sankt-Petersburg, Russia.
    Model set-up at COCOA study sites2015Rapport (Annet vitenskapelig)
    Abstract [en]

    COCOA will investigate physical, biogeochemical and biological processes in a combined and coordinated fashion to improve the understanding of the interaction of these processes on the removal of nutrients along the land-sea interface. The results from the project will be used to estimate nutrient retention capacity in the coastal zone of the entire Baltic Sea coast. An ensemble of biogeochemical models will be used in combination with field studies at seven different coastal study sites around the Baltic Sea. The present report is a deliverable of COCOA work package 5 (WP5). Within the objective of WP5 process understanding and process descriptions will be improved in state-of-the-art biogeochemical models of the Baltic Sea coastal zone. This report presents brief information about the models available for the COCOA project and defines the needed input to the models that will be set-up at several learning sites. The aim is to perform ensemble modelling at several sites, using at least two different models at each site. A pilot study to estimate nutrient retention capacity in the Stockholm Archipelago with the existing Swedish model system is ongoing and first results are presented and the concept of nutrient retention is briefly discussed. The existing models for different learning sites presented in the report are; 1) The Swedish model system SCM (Öre river estuary and the Stockholm archipelago) - A multi-box-model approach 2) The Danish model system FLEXSEM (Roskilde fjord) - A combined box-model and 3-D model approach 3) The Finnish model system ESIM-BFMSI (Tvärminne Archipelago) - A 1D box-model approach 4) The Polish model system M3D UG/ProDeMo (Puck Bay) - A 3-D model approach. Operational model. 5) The Lithuanian model system SYFEM/AQUABC (Curonian Lagoon) - A combined box-model and 3-D model approach 6) The Swedish open Baltic model system RCO-SCOBI (for the open Baltic Sea and the Gulf of Gdansk/Vistula). - A 3-D model approach In addition a biogeochemical model (Boudreau, 1996) for the Gulf of Finland (Russian State Hydrometeorological University model) is used to study the quantitative effect of Marenzelleria on the Gulf of Finland ecosystem. Process studies at selected sites will be performed with a reactive transport model developed at Utrecht University. Focus will be on the role of iron and phosphorus cycling. Process studies with the Danish model system will support the development of new parameterizations of nutrient fluxes taking benthic habitat into account. The new parameterizations of the nutrient fluxes will in addition also be implemented into SCM and the models will be used to estimate nutrient fluxes, retention times and the filter capacity of the coastal zones. The In Kind contributions from previously (in the literature) well described open Baltic Sea models RCO-SCOBI, BALTSEM, ERGOM and SPBEM that will be used for the description of open sea conditions are also briefly mentioned in the report with references to the relevant literature. 6) The Swedish open Baltic model system RCO-SCOBI (for the open Baltic Sea and the Gulf of Gdansk/Vistula). - A 3-D model approach In addition a biogeochemical model (Boudreau, 1996) for the Gulf of Finland (Russian State Hydrometeorological University model) is used to study the quantitative effect of Marenzelleria on the Gulf of Finland ecosystem. Process studies at selected sites will be performed with a reactive transport model developed at Utrecht University. Focus will be on the role of iron and phosphorus cycling. Process studies with the Danish model system will support the development of new parameterizations of nutrient fluxes taking benthic habitat into account. The new parameterizations of the nutrient fluxes will in addition also be implemented into SCM and the models will be used to estimate nutrient fluxes, retention times and the filter capacity of the coastal zones. The In Kind contributions from previously (in the literature) well described open Baltic Sea models RCO-SCOBI, BALTSEM, ERGOM and SPBEM that will be used for the description of open sea conditions are also briefly mentioned in the report with references to the relevant literature.

  • 113. Schneider, Bernd
    et al.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Lukkari, Kaarina
    Muller-Karulis, Barbel
    Neumann, Thomas
    Environmental Impacts-Marine Biogeochemistry2015Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Marine biogeochemistry deals with the budgets and transformations of biogeochemically reactive elements such as carbon, nitrogen and phosphorus. Inorganic nitrogen and phosphorus compounds are the major nutrients and control organic matter (biomass) production in the surface water. Due to various anthropogenic activities, the input of these nutrients into the Baltic Sea has increased drastically during the last century and has enhanced the net organic matter production by a factor of 2-4 (eutrophication). This has led to detrimental oxygen depletion and hydrogen sulphide production in the deep basins of the Baltic Sea. Model simulations based on the Baltic Sea Action Plan (BSAP) indicate that current eutrophication and thus extension of oxygen-depleted areas cannot be reversed within the next hundred years by the proposed nutrient reduction measures. Another environmental problem is related to decreasing pH (acidification) that is caused by dissolution of the rising atmospheric CO2. Estimates indicate a decrease in pH by about 0.15 during the last 1-2 centuries, and continuation of this trend may have serious ecological consequences. However, the concurrent increase in the alkalinity of the Baltic Sea may have significantly counteracted acidification.

  • 114.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Projected Change-Marine Physics2015Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This chapter assesses recent results of changes in water temperature, salinity, sea ice, storm surges and wind waves during the twenty-first century in scenario simulations for the Baltic Sea. There have been several improvements since the first Baltic Sea assessment of climate change: the number of relevant scenario simulations has increased, ensembles of transient simulations with improved models based upon the scenarios and global models of IPCC's Fourth Assessment Report (AR4) have been analysed, and changes in biogeochemical cycles are now considered. The scenario simulations project that water temperatures will increase in the future, with the greatest changes in the northern Baltic Sea during summer. In agreement with earlier studies, sea-ice cover is projected to decrease drastically. Salinity is projected to decrease due to increased river run-off, whereas the impact of wind changes on salinity is negligible because the latter is relatively small. However, uncertainty in salinity projections is large owing to considerable bias in the simulated water balance. According to one study, salt transport into the Baltic Sea is unchanged. Sea-level rise has greater potential to increase surge levels in the Baltic Sea than increased wind speed, and changes in wind waves are projected to be small.

  • 115. 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 shelf2015Inngår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, artikkel-id 26911Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 116. Weigel, Benjamin
    et al.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Blenckner, Thorsten
    Snickars, Martin
    Bonsdorff, Erik
    Long-term progression and drivers of coastal zoobenthos in a changing system2015Inngår i: Marine Ecology Progress Series, ISSN 0171-8630, E-ISSN 1616-1599, Vol. 528, s. 141-159Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 117. Sein, Dmitry V.
    et al.
    Mikolajewicz, Uwe
    Gröger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    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 validation2015Inngår i: Journal of Advances in Modeling Earth Systems, ISSN 1942-2466, Vol. 7, nr 1, s. 268-304Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 118.
    Wang, Shiyu
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Development and evaluation of a new regional coupled atmosphere-ocean model in the North Sea and Baltic Sea2015Inngår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, artikkel-id 24284Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 119. 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, Samhälle och säkerhet.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Uncertainty estimation for operational ocean forecast products-a multi-model ensemble for the North Sea and the Baltic Sea2015Inngår i: Ocean Dynamics, ISSN 1616-7341, E-ISSN 1616-7228, Vol. 65, nr 12, s. 1603-1631Artikkel i tidsskrift (Fagfellevurdert)
    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.

  • 120. Wells, Mark L.
    et al.
    Trainer, Vera L.
    Smayda, Theodore J.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    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 future2015Inngår i: Harmful Algae, ISSN 1568-9883, E-ISSN 1878-1470, Vol. 49, s. 68-93Artikkel i tidsskrift (Fagfellevurdert)
    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.

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