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  • 161. MacKenzie, Brian R.
    et al.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Lindegren, Martin
    Neuenfeldt, Stefan
    Eero, Margit
    Blenckner, Thorsten
    Tomczak, Maciej T.
    Niiranen, Susa
    Impact of Climate Change on Fish Population Dynamics in the Baltic Sea: A Dynamical Downscaling Investigation2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 6, p. 626-636Article in journal (Refereed)
    Abstract [en]

    Understanding how climate change, exploitation and eutrophication will affect populations and ecosystems of the Baltic Sea can be facilitated with models which realistically combine these forcings into common frameworks. Here, we evaluate sensitivity of fish recruitment and population dynamics to past and future environmental forcings provided by three ocean-biogeochemical models of the Baltic Sea. Modeled temperature explained nearly as much variability in reproductive success of sprat (Sprattus sprattus; Clupeidae) as measured temperatures during 1973-2005, and both the spawner biomass and the temperature have influenced recruitment for at least 50 years. The three Baltic Sea models estimate relatively similar developments (increases) in biomass and fishery yield during twenty-first century climate change (ca. 28 % range among models). However, this uncertainty is exceeded by the one associated with the fish population model, and by the source of global climate data used by regional models. Knowledge of processes and biases could reduce these uncertainties.

  • 162. Ruoho-Airola, Tuija
    et al.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Savchuk, Oleg P.
    Parviainen, Maija
    Tarvainen, Virpi
    Atmospheric Nutrient Input to the Baltic Sea from 1850 to 2006: A Reconstruction from Modeling Results and Historical Data2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 6, p. 549-557Article in journal (Refereed)
    Abstract [en]

    In this study, a consistent basin-wise monthly time series of the atmospheric nutrient load to the Baltic Sea during 1850-2006 was compiled. Due to the lack of a long time series (1850-1960) of nutrient deposition to the Baltic Sea, the data set was compiled by combining a time series of deposition data at the Baltic Nest Institute from 1970 to 2006, published historical monitoring data and deposition estimates, as well as recent modeled Representative Concentration Pathways (RCP) emission estimates. The procedure for nitrogen compounds included estimation of the deposition in a few intermediate reference years, linear interpolation between them, and the decomposition of annual deposition into a seasonal deposition pattern. As no reliable monitoring results were found for the atmospheric deposition of phosphorus during the early period of our study, we used published estimates for the temporal and spatial pattern of the phosphorus load.

  • 163.
    Hordoir, Robinson
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Effect of climate change on the thermal stratification of the baltic sea: a sensitivity experiment2012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 38, no 9-10, p. 1703-1713Article in journal (Refereed)
    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.

  • 164. Martensson, S.
    et al.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Pemberton, Per
    SMHI, Research Department, Oceanography.
    Haapala, J.
    Ridged sea ice characteristics in the Arctic from a coupled multicategory sea ice model2012In: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, ISSN 2169-9275, Vol. 117, article id C00D15Article in journal (Refereed)
    Abstract [en]

    In this study, a multicategory sea ice model with explicit ice classes for ridged and rafted ice was used to examine the evolution of deformed ice during the period 1980-2002. The results show that (1) ridged ice comprises roughly 45-60% of Arctic sea ice volume and 25-45% of the sea ice area, (2) most of the perennial ice consists of ridged ice, and (3) ridged ice exhibits a small seasonal variability. Our results also show an increase in mean ridged ice thickness of 4-6 cm yr(-1) during the summer in an area north of the Canadian Archipelago and a corresponding decrease in the East Siberian Sea and Nansen Basin. At the same time, Arctic sea ice age has been observed to decline and ice drift speed to increase during the simulation period. We connect these findings with a modeled regional increase in the production rate of ridged ice. Comparison of the multicategory model and a two category reference model shows a substantially increased ice production rate due to a more frequent occurrence of leads, resulting in an ice thickness increase of up to 0.8 m. Differences in ice physics between the multicategory and reference models also affect the freshwater content. The sum of liquid and solid freshwater content in the entire Arctic Ocean is about 10% lower and net precipitation (P-E) is about 7% lower as compared to the reference model.

  • 165.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Andersson, Helén
    SMHI, Research Department, Oceanography.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Gustafsson, B. G.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Modeling the combined impact of changing climate and changing nutrient loads on the Baltic Sea environment in an ensemble of transient simulations for 1961-20992012In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 39, no 9-10, p. 2421-2441Article in journal (Refereed)
    Abstract [en]

    The combined future impacts of climate change and industrial and agricultural practices in the Baltic Sea catchment on the Baltic Sea ecosystem were assessed. For this purpose 16 transient simulations for 1961-2099 using a coupled physical-biogeochemical model of the Baltic Sea were performed. Four climate scenarios were combined with four nutrient load scenarios ranging from a pessimistic business-as-usual to a more optimistic case following the Baltic Sea Action Plan (BSAP). Annual and seasonal mean changes of climate parameters and ecological quality indicators describing the environmental status of the Baltic Sea like bottom oxygen, nutrient and phytoplankton concentrations and Secchi depths were studied. Assuming present-day nutrient concentrations in the rivers, nutrient loads from land increase during the twenty first century in all investigated scenario simulations due to increased volume flows caused by increased net precipitation in the Baltic catchment area. In addition, remineralization rates increase due to increased water temperatures causing enhanced nutrient flows from the sediments. Cause-and-effect studies suggest that both processes may play an important role for the biogeochemistry of eutrophicated seas in future climate partly counteracting nutrient load reduction efforts like the BSAP.

  • 166.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Andersson, Helén
    SMHI, Research Department, Oceanography.
    ECOSUPPORT: A Pilot Study on Decision Support for Baltic Sea Environmental Management2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 6, p. 529-533Article in journal (Other academic)
  • 167.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Gustafson, B.G
    Kuznetsov, Ivan
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Neumann, T.
    Savchuk, O. P.
    Evaluation of biogeochemical cycles in an ensemble of three state-of-the-art numerical models of the Baltic Sea2011In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 88, no 2, p. 267-284Article in journal (Refereed)
    Abstract [en]

    Three state-of-the-art coupled physical–biogeochemical models, the BAltic sea Long-Term large-Scale Eutrophication Model (BALTSEM), the Ecological Regional Ocean Model (ERGOM), and the Swedish Coastal and Ocean Biogeochemical model coupled to the Rossby Centre Ocean circulation model (RCO–SCOBI), are used to calculate changing nutrient and oxygen dynamics in the Baltic Sea. The models are different in that ERGOM and RCO–SCOBI are three-dimensional (3D) circulation models while BALTSEM resolves the Baltic Sea into 13 dynamically interconnected and horizontally integrated sub-basins. The aim is to assess the simulated long-term dynamics and to discuss the response of the coupled physical–biogeochemical models to changing physical conditions and nutrient loadings during the period 1970–2005. We compared the long-term seasonal and annual statistics of inorganic nitrogen, phosphorus, and oxygen from hindcast simulations with those estimated from observations. We also studied the extension of hypoxic bottom areas covered by waters with O2 b2 ml O2 l −1 and cod reproductive volumes comprising waters with salinity N11 and O2 N2 ml O2 l −1 . The models reproduce much of the nutrient biogeochemical cycling in the Baltic proper. However, biases are larger in the Bothnian Sea and Bothnian Bay. No model shows outstanding performance in all aspects but instead the ensemble mean results are better than or as good as the results of any of the individual models. Uncertainties are primarily related to differences in the bioavailable fractions of nutrient loadings from land and parameterizations of key processes like sediment fluxes that are presently not well known. Also the uncertainty related to the initialization of the models in the early 1960s influence the modeled biogeochemical cycles during the investigated period. ©

  • 168.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Almroth-Rosell, Elin
    SMHI, Research Department, Oceanography.
    Andersen, Per
    Nautsvoll, Lars Johan
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Modelling the dynamics of harmful blooms of Chattonella sp. in the Skagerrak and the Kattegat2011In: ICES CM 2006/E:12, 2011Conference paper (Other academic)
    Abstract [en]

    The presentation shows observations, satellite images and model results describing the growth and spreading of Chattonella sp. flagellates in the Skagerrak and the Kattegat. Chattonella sp. is a harmful alga that may cause fish kills due to damage of the gills. Calm weather, stable water column stratification, and low turbulence may facilitate the onset of a Chattonella bloom. Results from the three-dimensional hydrodynamical model HIROMB (High Resolution Operational Model for the Baltic Sea) are used as forcing of a transport model that computes vertical and horizontal transports of chemical and biological compounds. A modified version of the Swedish Coastal and Ocean Biogeochemical model (SCOBI) is used to describe the temporal evolution of the phytoplankton spring blooms in the year 2001 when Chattonella was abundant and 2002 when only small amounts of Chattonella were observed. A comparison with satellite images and cell counts indicates that the model captures the main transport patterns of phytoplankton in the surface layers of the offshore areas. The Chattonella bloom of the model starts in the quite shallow parts of the western Kattegat and in the stratified coastal areas of the northern Skagerrak. The coastal waters near the river Göta Älv of Sweden also indicate a tendency of an increased occurrence of Chattonella. Chattonella is observed in the model during both years but the occurrence of Chattonella is more significant in the year 2001 than in 2002.

  • 169.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Almroth-Rosell, Elin
    SMHI, Research Department, Oceanography.
    Climate-related changes in marine ecosystems simulated with a three-dimensional coupled physical -biogeochemical model of the Baltic Sea2011In: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 48, p. 31-55Article in journal (Refereed)
  • 170.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Future projections of ecological patterns in the Baltic Sea2011Report (Other academic)
    Abstract [en]

    The impact of changing climate on Baltic Sea biogeochemical cycles at the end of the 21st century was studied using a three-dimensional coupled physical-biogeochemical model. Four climate change scenarios using regionalized data from two General Circulation Models (GCMs) and two greenhouse gas emission scenarios (A2, B2) have been investigated. In this study we have focused on maps of annual and seasonal mean changes of ecological quality indicators. We found that the impact of changing climate on the horizontal distribution of ecological parameters might be significant. For instance, in the scenario simulation with the largest changes secchi depth might decrease by up to 2 m in some regions. However, due to reduced stratification also increased secchi depths might occur.

  • 171.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Andersson, Helén
    SMHI, Research Department, Oceanography.
    Dieterich, Christian
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Gustafsson, B.
    Stockholm Resilience Centre/Baltic Nest Institute, Stockholm University, Stockholm, Sweden.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Transient scenario simulations for the Baltic Sea Region during the 21st century2011Report (Other academic)
    Abstract [en]

    The combined future impacts of climate change and industrial and agricultural practices in the Baltic Sea catchment on the Baltic Sea ecosystem were assessed. For this purpose 16 transient simulations for 1961-2099 using a coupled physical-biogeochemical model of the Baltic Sea have been performed. Four climate scenarios were combined with four nutrient load scenarios ranging from a pessimistic business-as-usual to a more optimistic case following the Baltic Sea Action Plan (BSAP). In this study we focussed on annual and seasonal mean changes of ecological quality indicators describing the environmental status of the Baltic Sea. In correspondence with earlier studies we found that the impact of changing climate on the Baltic biogeochemistry might be significant. Assuming reference loadings the water quality in all climate scenarios is reduced at the end of the century. The impact of nutrient load reductions according to the BSAP will be less effective in future climate compared to present climate. However, the results of the pessimistic business-as-usual scenario suggest that policy makers should act to avoid much worse environmental conditions than today.

  • 172.
    Andersson, Helén
    et al.
    SMHI, Research Department, Oceanography.
    Wallman, Patrik
    SMHI, Research Department, Hydrology.
    Donnelly, Chantal
    SMHI, Research Department, Hydrology.
    Visualization of hydrological, physical and biogeochemical modelling of the Baltic Sea using a GeoDomeTM2011Report (Other academic)
    Abstract [en]

    The ECOSUPPORT-project aims to help policy makers by supplying state-of-the-art research on the state of the Baltic Sea under different scenarios of nutrient supply, pressure from fisheries and impact of climate change. In order to make the research results accessible, a new form of scientific communication has been tested. Presentation of research data and physical, chemical and biogeochemical processes on land and in the sea were made using a special visualization platform, Uniview, which was projected onto a cupola-shaped screen inside an inflatable, enclosed dome. The visualization has been tested on different audiences including policy makers, politicians, researchers and university students. Overall, the response has been overwhelmingly positive with the audience expressing the view that the used visualization technique enhanced their understanding and receptiveness. This view was shared with the scientific presenters.

  • 173.
    Hansson, Martin
    et al.
    SMHI, Core Services.
    Andersson, Lars
    SMHI, Core Services.
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Areal Extent and Volume of Anoxia and Hypnoxia in the Baltic Sea, 1960-20112011Report (Other academic)
    Abstract [en]

    A climatology atlas of the oxygen situation in the deep water of the Baltic Sea from 1960 to 2011 has been created based on all available data from ICES. Additional data collected during the Baltic International Acoustic Survey (BIAS) have been added to the year 2011. For the autumn period, each profile in the data set was examined for the occurrence of hypoxia (oxygen deficiency) and anoxia (total absence of oxygen). The depths of the onset of hypoxia and anoxia were then interpolated between sampling stations producing two surfaces representing the depth at which hypoxic and anoxic conditions are found. The volume and area of hypoxia and anoxia have been calculated and the results have then been transformed to maps and diagrams to visualize the annual autumn oxygen situation during the analysed period. From the analysed oxygen data 1960-2011 a distinct regime shift has been identified in 1999. During the first regime, 1960 to 1999, hypoxia affected large areas and volumes while anoxic conditions affected only minor deep areas. After the regime shift in 1999 both the areal extent and volume of hypoxia and anoxia are elevated to levels never recorded before. The bottom areas of the Baltic Proper (including the Gulf of Finland and the Gulf of Riga) affected by anoxic conditions have increased from 5%, before the regime shift, to 15% after, i.e. by a factor of 3. The extent of hypoxia has increased from 22% to 28%, i.e. by a factor of ~1.3. Excluding the results from 2011, which are preliminary, the largest areal extent of anoxia, 18%, in the Baltic Proper was recorded in 2005 and the largest affected water volume, 10%, was recorded in 2001. The cause and ecosystem effects of the new behaviour of the Baltic Sea that has been recognized after the regime shift, with continuously extreme oxygen conditions, are still not fully understood. However, there are several likely contributory and concurrent causes to the recent development such as changes in winds, changes in frequency and characteristics of inflows, increased loading of organic matter to the deep water, altered vertical mixing and stratification, and changed freshwater runoff. Historically, the oxygen development in the deep water of the Baltic Sea has been investigated in detail and most of the processes involved, both physical and chemical, have been described. But the development during the 2000s is alarming and should be investigated thoroughly. The areal extent and volume of hypoxia have today probably reached the maximal possible extent due to the permanent stratification in the Baltic Proper. However, the extent and volume of anoxic conditions can still increase, which further can enhance the eutrophication of the Baltic Sea due to released phosphorus from sediments that previously have been oxygenated. Sammanfattning En klimatologisk atlas av syresituationen i Östersjöns djupvatten från 1960 till 2011 har skapats baserad på all tillgänglig data från ICES. Ytterligare data från Baltic International Acoustic Survey (BIAS) har inkluderats separat för 2011. Förekomsten av hypoxi (syrebrist) och anoxi (helt syrefria förhållanden) under höstperioden har undersökts i varje mätprofil. Djupet då 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. Utifrån analyserade data från perioden 1960-2011 har ett distinkt regimskifte skett 1999. Under den första regimen, från 1960 till 1999, påverkade hypoxi stora områden och volymer, medan anoxi enbart påverkade mindre djupområden. Efter regimskiftet 1999 har andelen hypoxi och anoxi förhöjts till nivåer som aldrig tidigare observerats i Östersjöns djupvatten. Utbredningen av bottnar påverkade av anoxi har i medeltal ökat från 5% av Egentliga Östersjöns (inklusive Finska viken och Rigabukten) bottenarea till 15%, i och med regimskiftet, d.v.s. med en faktor 3. Utbredningen av hypoxi har också ökat från 22% till 28% d.v.s. med en faktor ~1.3. Den största utbredningen av anoxi, 18%, i Egentliga Östersjön observerades 2005 och den största påverkade vattenvolymen, 10%, noterades 2001. Utvecklingen i Östersjön med fortsatt extrema syreförhållanden efter regimskiftet och dess orsaker och konsekvenser för Östersjöns ekosystem är idag inte helt klarlagd. Det finns emellertid flera troliga orsaker som kan samverka såsom; förändrade vindförhållanden, förändrad frekvens och karaktäristik av inflöden, ökad belastning av organiskt material till djupvattnet, förändrad vertikal omblandning samt skiktning och ändrad tillrinning till Östersjön. Historiskt så har syreförhållanden i Östersjön undersökts i detalj och de flesta processer, både fysiska och kemiska finns beskrivna. Men utvecklingen under 2000-talet är alarmerande och måste noggrant undersökas. Utbredningen och volymen av hypoxi har idag (2011) antagligen nått den övre gränsen för vad som är fysiskt möjligt med den permanenta skiktning som finns i Östersjön. De anoxiska förhållandena kan dock fortsatt öka om den negativa utvecklingen fortsätter, vilket ytterligare kan förvärra övergödningsproblematiken i Östersjön då mer fosfor kan frigöras från bottnar som tidigare varit syresatta.

  • 174.
    Schimanke, Semjon
    et al.
    SMHI, Research Department, Oceanography.
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Strandberg, Gustav
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    A regional climate model simulation over the Baltic Sea region for the last Millennium2011Report (Other academic)
    Abstract [en]

    Variability and long-term climate change in Fennoscandia is investi-gated in a 1000-year long climate model simulation. We use the Rossby Centre Regional Climate model (RCA3) with boundaryconditions from a General Circulation Model (GCM). Solar variability, changes in orbital parameters and changes in greenhouse gases over the last millennium are used to force the climate models. It is shown that RCA3 generates a warm period corresponding to the Medieval Climate Anomaly (MCA) being the warmest period within the millennium apart from the 20th century. Moreover, an analogy forthe Little Ice Age (LIA) was shown to be the coldest period. The simulated periods are 1100-1299 A.D. for the MCA and 1600-1799 A.D. for the LIA, respectively. This is in agreement with recon-structions and mostly related to changes in the solar irradiance. We found that multi decadal variability has an important impact on the appearance of the MCA and LIA. Moreover, multi decadal variability mayhelp to explain sometimes contradicting reconstructions if these are representative for relatively short non-overlapping periods. In addition to time series, we investigate spatial patterns of temperature, sealevel pressure, precipitation, cloud cover, wind speed and gustiness for annual and seasonal means. Most parameters show the clearest response for the winter season. For instance, winter during the MCAare 1-2.5 K warmer than during the LIA for multi decadal averages.

  • 175.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Hansen, J.
    National Environmental Research Institute, Aarhus University, Denmark.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Myrberg, K.
    Finnish Environment Institute, Finland Nordic.
    Ryabchenko, V.A.
    St. Petersburg Branch, P.P.Shirshov Institute of Oceanology, Russia.
    Skogen, Morten
    Institute of Marine Research, Norway.
    Eutrophication Status Report of the North Sea, Skagerrak, Kattegat and the Baltic Sea: A model study Years 2001-20052011Report (Other academic)
    Abstract [en]

    This joint status report for the North Sea, Skagerrak, Kattegat and the Baltic Sea area is carried out by SMHI Sweden, IMR Norway, NERI Denmark, SPBIO Russia, and SYKE Finland as a part of the project “A Baltic and NORth sea Model eutrophication Assessment in a future cLimate” (ABNORMAL), supported by the Nordic Council of Ministers’ Sea and Air Group (NMR-HLG). The previous NMR-HLG projects NO COMMENTS and BANSAI focused on the establishment and main-tenance of operational models and the use of these to develop methods for assessing the eutrophication status. Within ABNORMAL the issues are brought forward with a focus also on the use of ecological models for an assessment of marine eutrophication in a future climate. The main finding of this study is the proposed way of combining observations and results from an ensemble of ecological models to make an assessment of the eutrophication status in present climate for five different years (2001-2005). Threshold values and methodology from the Oslo and Paris Commissions (OSPAR) and the Helsinki Commission (HELCOM) are used and possible improvements of the methods are briefly discussed. The assessment of eutrophication status according to the integration of the categorized assessment parameters indicates that the Kattegat, the Danish Straits, the Gulf of Finland, the Gotland Basin as well as main parts of the Arkona Basin, the Bornholm Basin, and the Baltic proper may be classified as problem areas. The main part of the North Sea and also the Skagerrak are non-problem areas while the main parts of the Gulf of Bothnia, Gulf of Riga and the entire southeastern continental coast of the North Sea may be classified as potential problem areas.

  • 176.
    Löptien, Ulrike
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Simulated distribution of colored dissolved organic matter in the Baltic Sea2011Report (Other academic)
    Abstract [en]

    The Baltic Sea is optically a multi-componental water and has exceedingly high levels of colored dissolved organic matter (CDOM, also referred as yellow matter, gilvin or gelbstoff). CDOM is a complex mixture of chemical bonds originating from the decay of photosynthetically produced organic matter. It influences the aquatic light field substantially. A quantitative description of the dynamics and variability is often required to predict accurately light penetration and hereafter e.g. primary production. The present study is a first attempt to include CDOM into a Baltic Sea model. The model integrations are based on a fixed concentration in the 30 major rivers. In the absence of comprehensive measurements, a river inflow proportional to total organic carbon is assumed. Since origin and fate are still a matter of discussion, we test various decay rates of CDOM and compare the results with satellite observations. Best results are obtained when assuming a light dependent decay, compared to a temperature or time dependent decay. Treating CDOM as a conservative tracer does not lead to satisfactory results. Sammanfattning

  • 177.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Hall, Per O. J.
    Transport of fresh and resuspended particulate organic material in the Baltic Sea - a model study2011In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 87, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    A fully coupled high-resolution 3-dimensional biogeochemical-physical ocean model including an empirical wave model was used to investigate the long-term average (1970-2007) distributions and transports of resuspended matter and other types of suspended organic matter in the Baltic Sea. Modelled bottom types were compared to observations and the results showed that the model successfully managed to capture the horizontal, as well as the vertical, distribution of the different bottom types: accumulation, transport and erosion bottoms. The model also captured well the nutrient element contents in the sediments. On average the largest contribution of resuspended organic carbon to the transport of total organic carbon is found at erosion and transport bottoms. Although the relative transport of resuspended organic carbon at deeper accumulation bottoms in general is low (< 10% of total), the central parts of the sub-basins act on average as sinks that import organic matter while the more shallow areas and the coastal regions acts as sources of organic carbon in the water column. This indicates that the particulate organic matter produced in erosion and transport areas might be kept in suspension long enough to be transported and settle in less energetic areas, i.e. on accumulation bottoms. (C) 2011 Elsevier B.V. All rights reserved.

  • 178.
    Löptien, Ulrike
    SMHI, Research Department, Oceanography.
    Steady states and sensitivities of commonly used pelagic ecosystem model components2011In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 222, no 8, p. 1376-1386Article in journal (Refereed)
    Abstract [en]

    Pelagic, coupled ocean circulation-ecosystem models, are widely used in climate research. These tools aim to quantify fluxes of nutrients and carbon in the ocean and are, increasingly, the base of future projections. For this purpose it is crucial to quantify and identify the sources of uncertainties. In contrast to physical models, the underlying equations for ecosystem models are derived from empirical relationships rather than based on first principles. This resulted in the development of a multitude of different ecosystem models - different in respect to both, underlying principles and complexity. Clearly, the question arises, to what extent the sensitivities of these models are comparable. This study focuses on the intrinsic dynamics of some widely used, simple (containing 2-3 prognostic variables) ecosystem models in a 0-D framework (i.e., comprising only the well-mixed oceanic surface layer). A suite of differing model approaches is tuned such that their behavior is similar. The setup resembles the well-mixed oceanic surface layer in the Baltic proper. It is illustrated that strong differences between the model approaches appear due to exemplary, anticipated changes in the external nutrient and light conditions. Herewith, we demonstrate the well-known, but rarely demonstrated fact that, apparent consistency between modeled prognostic variables with today's data bases is not necessarily a good measure of forecast skill. The causes which lead to the different sensitivities are illustrated by considering the steady state solutions. It is pointed out, that apparently small changes in the model formulations can result in very different dynamical behavior and an enormous spread between the model approaches, despite the feasibility to tune a common behavior in a limited range of light and nutrient supply. In our examples, the sensitivity is mainly a function of the formulation of the loss rate of phytoplankton. It is thus, in particular, the formulation of highly unknown heteorotrophic processes that determines the model sensitivity. (C) 2011 Elsevier B.V. All rights reserved.

  • 179. Granhag, Lena
    et al.
    Moller, Lene Friis
    Hansson, Lars J.
    SMHI, Research Department, Oceanography.
    Size-specific clearance rates of the ctenophore Mnemiopsis leidyi based on in situ gut content analyses2011In: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 33, no 7, p. 1043-1052Article in journal (Refereed)
    Abstract [en]

    The ctenophore Mnemiopsis leidyi can consume large amounts of zooplankton prey. However, quantitative measurements of feeding rates, based on field data, are scarce. We measured the time required by the invasive M. leidyi to digest naturally occurring prey species in the Gullmar fjord, Sweden. Digestion times were related to prey size and type, number of prey in the gut and size of the predator. Large prey species or many prey in the gut resulted in longer digestion times compared with small or few prey, but digestion time also varied with the size of M. leidyi. The prey-and predator-specific digestion times were used together with in situ prey concentrations and gut contents of M. leidyi to calculate the clearance rates. Clearance rate as a function of ctenophore size is presented for the most abundant mesozooplankton: Acartia sp., Oithona sp., Oikopleura dioica and Penilia avirostris. On the basis of the relation between digestion time and the carbon content ratio between prey and predator, we discuss the possible effects of mixed prey assemblages on the estimates of clearance rates.

  • 180. Andersen, Jesper H.
    et al.
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Backer, Hermanni
    Carstensen, Jacob
    Claussen, Ulrich
    Fleming-Lehtinen, Vivi
    Jarvinen, Marko
    Kaartokallio, Hermanni
    Knuuttila, Seppo
    Korpinen, Samuli
    Kubiliute, Aiste
    Laamanen, Maria
    Lysiak-Pastuszak, Elzbieta
    Martin, Georg
    Murray, Ciaran
    Mohlenberg, Flemming
    Nausch, Guenther
    Norkko, Alf
    Villnas, Anna
    Getting the measure of eutrophication in the Baltic Sea: towards improved assessment principles and methods2011In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 106, no 2, p. 137-156Article in journal (Refereed)
    Abstract [en]

    The eutrophication status of the entire Baltic Sea is classified using a multi-metric indicator-based assessment tool. A total of 189 areas are assessed using indicators where information on reference conditions (RefCon), and acceptable deviation (AcDev) from reference condition could be combined with national monitoring data from the period 2001-2006. Most areas (176) are classified as 'affected by eutrophication' and only two open water areas and 11 coastal areas are classified as 'unaffected by eutrophication'. The classification is made by application of the recently developed HELCOM Eutrophication Assessment Tool (HEAT), which is described in this paper. The use of harmonized assessment principles and the HEAT tool allows for direct comparisons between different parts of the Baltic Sea despite variations in monitoring activities. The impaired status of 176 areas is directly related to nutrient enrichment and elevated loads from upstream catchments. Baltic Sea States have implemented nutrient management strategies since years which have reduced nutrient inputs. However, eutrophication is still a major problem for large parts of the Baltic Sea. The 2007 Baltic Sea Action Plan is projected to further reduce nutrient inputs aiming for a Baltic Sea unaffected by eutrophication by 2021.

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