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  • 101.
    Pemberton, Per
    et al.
    SMHI, Research Department, Oceanography.
    Nilsson, J.
    The response of the central Arctic Ocean stratification to freshwater perturbations2016In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 121, no 1, p. 792-817Article in journal (Refereed)
    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.

  • 102.
    Axell, Lars
    et al.
    SMHI, Research Department, Oceanography.
    Liu, Ye
    SMHI, Research Department, Oceanography.
    Application of 3-D ensemble variational data assimilation to a Baltic Sea reanalysis 1989-20132016In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 68, article id 24220Article in journal (Refereed)
    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.

  • 103.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Almroth-Rosell, Elin
    SMHI, Research Department, Oceanography.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    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 sites2015Report (Other academic)
    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.

  • 104. Schneider, Bernd
    et al.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Lukkari, Kaarina
    Muller-Karulis, Barbel
    Neumann, Thomas
    Environmental Impacts-Marine Biogeochemistry2015Chapter in book (Other academic)
    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.

  • 105.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Projected Change-Marine Physics2015Chapter in book (Other academic)
    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.

  • 106. Groger, Matthias
    et al.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Thermal air-sea coupling in hindcast simulations for the North Sea and Baltic Sea on the NW European shelf2015In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 26911Article in journal (Refereed)
    Abstract [en]

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

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

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

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

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

  • 109.
    Wang, Shiyu
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Doescher, Ralf
    SMHI, Research Department, Climate research - Rossby Centre.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Samuelsson, Patrick
    SMHI, Research Department, Climate research - Rossby Centre.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Development and evaluation of a new regional coupled atmosphere-ocean model in the North Sea and Baltic Sea2015In: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 67, article id 24284Article in journal (Refereed)
    Abstract [en]

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

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

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

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

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

  • 112.
    Hordoir, Robinson
    et al.
    SMHI, Research Department, Oceanography.
    Axell, Lars
    SMHI, Research Department, Oceanography.
    Löptien, Ulrike
    SMHI, Research Department, Oceanography.
    Dietze, Heiner
    Kuznetsov, Ivan
    SMHI, Research Department, Oceanography.
    Influence of sea level rise on the dynamics of salt inflows in the Baltic Sea2015In: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 120, no 10, p. 6653-6668Article in journal (Refereed)
    Abstract [en]

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

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

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

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

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

  • 115. Vuorinen, Ilppo
    et al.
    Hanninen, Jari
    Rajasilta, Marjut
    Laine, Paivi
    Eklund, Jan
    Montesino-Pouzols, Federico
    Corona, Francesco
    Junker, Karin
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Dippner, Joachim W.
    Scenario simulations of future salinity and ecological consequences in the Baltic Sea and adjacent North Sea areas - Implications for environmental monitoring (vol 50, pg 196, 2015)2015In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 53, p. 294-294Article in journal (Refereed)
  • 116.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Kuznetsov, Ivan
    Hall, Per O. J.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A new approach to model oxygen dependent benthic phosphate fluxes in the Baltic Sea2015In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 144, p. 127-141Article in journal (Refereed)
    Abstract [en]

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

  • 117.
    Pemberton, Per
    et al.
    SMHI, Research Department, Oceanography.
    Nilsson, Johan
    Hieronymus, Magnus
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Arctic Ocean Water Mass Transformation in S-T Coordinates2015In: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 45, no 4, p. 1025-1050Article in journal (Refereed)
    Abstract [en]

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

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

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

  • 119. Omstedt, Anders
    et al.
    Edman, Moa
    SMHI, Research Department, Oceanography.
    Claremar, Bjorn
    Rutgersson, Anna
    SMHI, Research Department, Climate research - Rossby Centre.
    Modelling the contributions to marine acidification from deposited SOx, NOx, and NHx in the Baltic Sea: Past and present situations2015In: Continental Shelf Research, ISSN 0278-4343, E-ISSN 1873-6955, Vol. 111, p. 234-249Article in journal (Refereed)
    Abstract [en]

    We have examined the effects of historical atmospheric depositions of sulphate, nitrate, and ammonium from land and shipping on the acid-base balance in the Baltic Sea. The modelling considers the 1750-2014 period, when land and ship emissions changed greatly, with increasing carbon dioxide concentrations, SOx, NOx, and NHx emissions, and nutrient loads. The present results indicate that Baltic Sea acidification due to the atmospheric deposition of acids peaked around 1980, with a pH cumulative decrease of approximately 10(-2) in surface waters. This is one order of magnitude less than the cumulative acidification due to increased atmospheric CO2. The acidification contribution of shipping is one order of magnitude less than that of land emissions. However, the pH trend due to atmospheric acids has started to reverse due to reduced land emissions, though the effect of shipping is ongoing. The effect of strong atmospheric acids on Baltic Sea water depends on the region and period studied. The largest total alkalinity sink per surface area is in the south-western Baltic Sea where shipping is intense. Considering the entire Baltic Sea over the 2001-2010 period, the pH changes are approximately -3 x 10(-3) to -11 x 10(-3) and -4 x 10(-4) to -16 x 10(-4) pH units attributable to all emissions and ship emissions only, respectively. The corresponding changes in total alkalinity are approximately -10 to -30 mu mol kg(-1) and -1 to -4 mu mol kg(-1) attributable to all emissions and ship emissions only, respectively. (C) 2015 Elsevier Ltd. All rights reserved.

  • 120. Moksnes, Per-Olav
    et al.
    Corell, Hanna
    Tryman, Kentaroo
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Jonsson, Per R.
    Larval behavior and dispersal mechanisms in shore crab larvae (Carcinus maenas): Local adaptations to different tidal environments?2014In: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 59, no 2, p. 588-602Article in journal (Refereed)
    Abstract [en]

    Using a combination of empirical and model studies we tested whether European shore crab larvae (Carcinus maenas) from environments with different tidal regimes in the North Sea area have different swimming behaviors, and whether this affects connectivity and settlement success of larvae. Laboratory studies demonstrated the presence of an inherited tidal migration rhythm in newly hatched crab larvae from the mesotidal Danish Wadden Sea, and field studies showed that postlarvae swam in surface water almost exclusively during flood tides, suggesting that larvae use selective tidal stream transport to control the dispersal process. In contrast, shore crab larvae from microtidal Skagerrak displayed a nocturnal vertical migration behavior that appeared to switch to a diurnal behavior at the end of the postlarval phase, indicating an adaptation to avoid visual predators and to use wind-driven transport to reach shallow settlement areas. A biophysical model showed that tidal-migrating larvae in the Wadden Sea had two times higher settlement success than larvae with a diel behavior. However, no differences in settlement success were found between the two larval behaviors in microtidal Skagerrak, where lower fitness is suggested for tidal-migrating larvae due to higher predation mortality from visual predators. We suggest that the differences in inherited larval behavior in larvae from meso-and microtidal regions reflect local adaptations maintained through natural selection of successful recruits. Consistent with recent population genetic studies, modeled connectivity of shore crabs indicated an oceanographic dispersal barrier to gene flow in Eastern Wadden Sea that may facilitate such adaptations.

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