Change search
Refine search result
78910111213 181 - 200 of 374
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 181. Conley, Daniel J.
    et al.
    Carstensen, Jacob
    Aigars, Juris
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Bonsdorff, Erik
    Eremina, Tatjana
    Haahti, Britt-Marie
    Humborg, Christoph
    Jonsson, Per
    Kotta, Jonne
    Lannegren, Christer
    Larsson, Ulf
    Maximov, Alexey
    Medina, Miguel Rodriguez
    Lysiak-Pastuszak, Elzbieta
    Remeikaite-Nikiene, Nijole
    Walve, Jakob
    Wilhelms, Sunhild
    Zillen, Lovisa
    Hypoxia Is Increasing in the Coastal Zone of the Baltic Sea2011In: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 45, no 16, p. 6777-6783Article in journal (Refereed)
    Abstract [en]

    Hypoxia is a well-described phenomenon in the offshore waters of the Baltic Sea with both the spatial extent and intensity of hypoxia known to have increased due to anthropogenic eutrophication, however, an unknown amount of hypoxia is present in the coastal zone. Here we report on the widespread unprecedented occurrence of hypoxia across the coastal zone of the Baltic Sea. We have identified 115 sites that have experienced hypoxia during the period 1955-2009 increasing the global total to ca. 500 sites, with the Baltic Sea coastal zone containing over 20% of all known sites worldwide. Most sites experienced episodic hypoxia, which is a precursor to development of seasonal hypoxia. The Baltic Sea coastal zone displays an alarming trend with hypoxia steadily increasing with time since the 1950s effecting nutrient biogeochemical processes, ecosystem services, and coastal habitat.

  • 182.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Andersson, H. C.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Gustafsson, B. G.
    Kuznetsov, Ivan
    SMHI, Research Department, Oceanography.
    Muller-Karulis, B.
    Neumann, T.
    Savchuk, O. P.
    Hypoxia in future climates: A model ensemble study for the Baltic Sea2011In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, article id L24608Article in journal (Refereed)
    Abstract [en]

    Using an ensemble of coupled physical-biogeochemical models driven with regionalized data from global climate simulations we are able to quantify the influence of changing climate upon oxygen conditions in one of the numerous coastal seas (the Baltic Sea) that suffers worldwide from eutrophication and from expanding hypoxic zones. Applying various nutrient load scenarios we show that under the impact of warming climate hypoxic and anoxic areas will very likely increase or at best only slightly decrease (in case of optimistic nutrient load reductions) compared to present conditions, regardless of the used global model and climate scenario. The projected decreased oxygen concentrations are caused by (1) enlarged nutrient loads due to increased runoff, (2) reduced oxygen flux from the atmosphere to the ocean due to increased temperature, and (3) intensified internal nutrient cycling. In future climate a similar expansion of hypoxia as projected for the Baltic Sea can be expected also for other coastal oceans worldwide. Citation: Meier, H. E. M., H. C. Andersson, K. Eilola, B. G. Gustafsson, I. Kuznetsov, B. Muller-Karulis, T. Neumann, and O. P. Savchuk (2011), Hypoxia in future climates: A model ensemble study for the Baltic Sea, Geophys. Res. Lett., 38, L24608, doi:10.1029/2011GL049929.

  • 183.
    Löptien, Ulrike
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    The influence of increasing water turbidity on the sea surface temperature in the Baltic Sea: A model sensitivity study2011In: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 88, no 2, p. 323-331Article in journal (Refereed)
    Abstract [en]

    The aim of the present study is to investigate the influence of enhanced absorption of sunlight at the sea surface due to increasing water turbidity and its effect on the sea surface temperatures (SST) in the Baltic Sea. The major question behind our investigations is, whether this effect needs to be included in Baltic Sea circulation models or can be neglected. Our investigations cover both, mean state and SST trends during the recent decades. To quantify the impact of water turbidity on the mean state different sensitivity ocean hind-cast experiments are performed. The state-of-the art ocean model RCO (Rossby Centre Ocean model) is used to simulate the period from 1962 to 2007. In the first simulation, a spatially and temporally constant value for the attenuation depth is used, while in the second experiment a climatological monthly mean, spatially varying attenuation coefficient is derived from satellite observations of the diffuse attenuation coefficient at 490 nm. The inclusion of a spatially varying light attenuation leads to significant SST changes during summer. Maximum values of + 0.5 K are reached in the Gulf of Finland and close to the eastern coasts, when compared to a fixed attenuation of visible light of 0.2 m(-1). The temperature anomalies basically match the pattern of increased light attenuation with strongest effects in shallow waters. Secondary effects due to changes in the current system are of minor importance. Similar results are obtained when considering trends. In the absence of long-term basin wide observations of attenuation coefficients, some idealizations have to be applied when investigating the possible influence of long-term changes in water turbidity on the SST. Two additional sensitivity experiments are based on a combination of long-term Secchi depth station observations and the present day pattern of water turbidity, as observed by satellite. We show the potential of increased water turbidity to affect the summer SST trends in the Baltic Sea significantly, while the estimated effect is apparently too small to explain the overall extreme summer trends observed in the Baltic Sea. (C) 2011 Elsevier B.V. All rights reserved.

  • 184. Bal, S.
    et al.
    Schimanke, Semjon
    SMHI, Research Department, Oceanography.
    Spangehl, T.
    Cubasch, U.
    On the robustness of the solar cycle signal in the Pacific region2011In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 38, article id L14809Article in journal (Refereed)
    Abstract [en]

    The potential role of the stratosphere for the 11-year solar cycle signal in the Pacific region is investigated by idealized simulations using a coupled atmosphere-ocean general circulation model. The model includes a detailed representation of the stratosphere and accounts for changes in stratospheric heating rates from prescribed time dependent variations of ozone and spectrally high resolved solar irradiance. Three transient simulations are performed spanning 21 solar cycles each. The simulations use slightly different ozone perturbations representing uncertainties of solar induced ozone variations. The model reproduces the main features of the 20th century observed solar response. A persistent mean sea level pressure response to solar forcing is found for the eastern North Pacific extending over North America. Moreover, there is evidence for a La Nina-like response assigned to solar maximum conditions with below normal SSTs in the equatorial eastern Pacific, reduced equatorial precipitation, enhanced off-equatorial precipitation and an El Nino-like response a couple of years later, thus confirming the response to solar forcing at the surface seen in earlier studies. The amplitude of the solar signal in the Pacific region depends to a great extent on the choice of the centennial period averaged. Citation: Bal, S., S. Schimanke, T. Spangehl, and U. Cubasch (2011), On the robustness of the solar cycle signal in the Pacific region, Geophys. Res. Lett., 38, L14809, doi:10.1029/2011GL047964.

  • 185. Soomere, Tarmo
    et al.
    Delpeche, Nicole
    Viikmaee, Bert
    Quak, Ewald
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Doeoes, Kristofer
    Patterns of current-induced transport in the surface layer of the Gulf of Finland2011In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 16, p. 49-63Article in journal (Refereed)
    Abstract [en]

    The Lagrangian trajectory model TRACMASS based on an Eulerian field of velocities (calculated using the Rossby Centre Ocean Model), combined with relevant statistical analysis, is used for the identification of transport patterns in the surface layer of the Gulf of Finland from 1987-1991. The analysis of velocity fields and properties of net and bulk transport (the distance between the start and end positions of a trajectory, and the total length of the trajectory, respectively) shows the presence of semi-persistent (with a typical lifetime from a week to a few months) features of the surface-layer dynamics, a part of which evidently cannot be extracted directly from the velocity fields. The modelled surface dynamics mostly hosts an Ekman-type drift and, in yearly average, contains an anticyclonic gyre occupying the western part of the gulf. The prevailing transport directions to the east and slightly to the south match the direction of the Ekman surface drift created by predominant south-western winds. The spatial patterns of the net transport substantially vary over different seasons. The most intense net transport along the coasts occurs in the western and central parts of the gulf but contains relatively intense largely meridional transport pathways in some seasons.

  • 186. Reckermann, Marcus
    et al.
    Langner, Joakim
    SMHI, Research Department, Air quality.
    Omstedt, Anders
    Göteborgs Universitet.
    von Storch, Hans
    Keevallik, Sirje
    Schneider, Bernd
    Arheimer, Berit
    SMHI, Research Department, Hydrology.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Huenicke, Birgit
    BALTEX-an interdisciplinary research network for the Baltic Sea region2011In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 6, no 4, article id 045205Article in journal (Refereed)
    Abstract [en]

    BALTEX is an environmental research network dealing with the Earth system of the entire Baltic Sea drainage basin. Important elements include the water and energy cycle, climate variability and change, water management and extreme events, and related impacts on biogeochemical cycles. BALTEX was founded in 1993 as a GEWEX continental-scale experiment and is currently in its second 10 yr phase. Phase I (1993-2002) was primarily dedicated to hydrological, meteorological and oceanographic processes in the Baltic Sea drainage basin, hence mostly dealt with the physical aspects of the system. Scientific focus was on the hydrological cycle and the exchange of energy between the atmosphere, the Baltic Sea and the surface of its catchment. The BALTEX study area was hydrologically defined as the Baltic Sea drainage basin. The second 10 yr phase of BALTEX (Phase II: 2003-12) has strengthened regional climate research, water management issues, biogeochemical cycles and overarching efforts to reach out to stakeholders and decision makers, as well as to foster communication and education. Achievements of BALTEX Phase II have been the establishment of an assessment report of regional climate change and its impacts on the Baltic Sea basin (from hydrological to biological and socio-economic), the further development of regional physical climate models and the integration of biogeochemical and ecosystem models. BALTEX features a strong infrastructure, with an international secretariat and a publication series, and organizes various workshops and conferences. This article gives an overview of the BALTEX programme, with an emphasis on Phase II, with some examples from BALTEX-related research.

  • 187.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Gustafson, B.G.
    Baltic Nest Institute, Resilience Centre, Stockholm University, Sweden.
    Hordoir, Robinson
    SMHI, Research Department, Oceanography.
    Höglund, Anders
    SMHI, Research Department, Oceanography.
    Kuznetsov, I.
    Baltic Sea Research Institute Warnemünde, Germany.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Savchuk, O.P.
    Baltic Nest Institute, Resilience Centre, Stockholm University, Sweden.
    Quality assessment of state-of-the-art coupled physical-biogeochemical models in hind cast simulations 1970-20052010Report (Other academic)
    Abstract [en]

    The objectives of the project ECOSUPPORT (Advanced modeling tool for scenarios of the Baltic Sea ECOsystem to SUPPORT decision making) are to calculate the combined effects of changing climate and changing human activity (e.g. changing nutrient loads) on the Baltic Sea ecosystem. Three state-of-the-art coupled physical-biogeochemical models (BALTSEM, ERGOM, and RCO-SCOBI) are used to calculate changing concentrations of nitrate, ammonium, phosphate, diatoms, flagellates, cyanobacteria, zooplankton, detritus, and oxygen in the Baltic Sea. The models are structurally different in that ERGOM and RCO-SCOBI are 3D circulation models with uniform high horizontal resolution while BALTSEM resolves the Baltic Sea spatially in 13 sub-basins. This report summarises first results of the quality assessment and model intercomparison within ECOSUPPORT. Results from hindcast simulations are compared with observations for the period 1970-2005. We found that all three investigated models are able to reproduce the observed variability of biogeochemical cycles well. 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. Avsikten med projektet ECOSUPPORT (Advanced modeling tool for scenarios of the Baltic Sea ECOsystem to SUPPORT decision making) är att undersöka hur klimatförändringar tillsammans med mänsklig aktivitet (förändrad närsaltstillförsel) påverkar Östersjöns ekosystem. Tre kopplade fysiska-biogeokemiska modeller (BALTSEM, ERGOM, and RCO-SCOBI) används för att beräkna hur koncentrationer av nitrat, ammonium, fosfat, diatoméer, flagellater, cyanobakterier, djurplankton, detritus och löst syrgas i Östersjön förändras. Modellerna skiljer sig strukturellt åt genom att ERGOM och RCO-SCOBI är tredimensionella modeller med hög horisontell upplösning medan BALTSEM delar upp östersjön rumsligt i 13 delbassänger. Denna rapport sammanfattar resultaten från en första modelljämförelse och kvalitetsbedömning där modellresultat för tidsperioden 1970-2005 jämförs med observationer från samma period. Alla tre modellerna visar att de kan återskapa den observerade biogeokemiska variabiliteten väl. Osäkerheter är huvudsakligen relaterade till skillnader i andelen av näringstillförseln från land som antas vara biologiskt tillgänglig och till beskrivningarna av viktiga processer, som t.ex. flöden från sedimenten, där kunskapen för närvarande är bristfällig.

  • 188.
    Doescher, Ralf
    et al.
    SMHI, Research Department, Climate research - Rossby Centre.
    Wyser, Klaus
    SMHI, Research Department, Climate research - Rossby Centre.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Qian, Minwei
    Redler, Ren
    Quantifying Arctic contributions to climate predictability in a regional coupled ocean-ice-atmosphere model2010In: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 34, no 7-8, p. 1157-1176Article in journal (Refereed)
    Abstract [en]

    The relative importance of regional processes inside the Arctic climate system and the large scale atmospheric circulation for Arctic interannual climate variability has been estimated with the help of a regional Arctic coupled ocean-ice-atmosphere model. The study focuses on sea ice and surface climate during the 1980s and 1990s. Simulations agree reasonably well with observations. Correlations between the winter North Atlantic Oscillation index and the summer Arctic sea ice thickness and summer sea ice extent are found. Spread of sea ice extent within an ensemble of model runs can be associated with a surface pressure gradient between the Nordic Seas and the Kara Sea. Trends in the sea ice thickness field are widely significant and can formally be attributed to large scale forcing outside the Arctic model domain. Concerning predictability, results indicate that the variability generated by the external forcing is more important in most regions than the internally generated variability. However, both are in the same order of magnitude. Local areas such as the Northern Greenland coast together with Fram Straits and parts of the Greenland Sea show a strong importance of internally generated variability, which is associated with wind direction variability due to interaction with atmospheric dynamics on the Greenland ice sheet. High predictability of sea ice extent is supported by north-easterly winds from the Arctic Ocean to Scandinavia.

  • 189. Eriksson, Leif E. B.
    et al.
    Borenäs, Karin
    SMHI, Core Services.
    Dierking, Wolfgang
    Berg, Anders
    Santoro, Maurizio
    Pemberton, Per
    SMHI, Research Department, Oceanography.
    Lindh, Henrik
    SMHI, Core Services.
    Karlson, Bengt
    SMHI, Research Department, Oceanography.
    Evaluation of new spaceborne SAR sensors for sea-ice monitoring in the Baltic Sea2010In: CANADIAN JOURNAL OF REMOTE SENSING, ISSN 1712-7971, Vol. 36, p. S56-S73Article in journal (Refereed)
    Abstract [en]

    In this study, synthetic aperture radar (SAR) data from the Advanced Land Observing Satellite (ALOS) and the Envisat, RADARSAT-2, and TerraSAR-X satellites were compared to evaluate their usefulness for sea-ice monitoring in the Baltic Sea. Radar signature characteristics at different frequencies, polarizations, and spatial resolutions are presented for three examples from 2009. C-band like-polarization data, which have been used for operational sea-ice mapping since the early 1990s, serve as a reference. Advantages and disadvantages were identified for the different SAR systems and imaging modes. One conclusion is that cross-polarized data improve the discrimination between sea ice and open water. Another observation is that it is easier to identify ice ridges in L-band data than in images from shorter wavelengths. The information content of X-and C-band images is largely equivalent, whereas L-band data provide complementary information. L-band SAR also seems to be less sensitive to wet snow cover on the ice.

  • 190. Andersen, Jesper H.
    et al.
    Murray, Ciaran
    Kaartokallio, Hermanni
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Molvaer, Jarle
    A simple method for confidence rating of eutrophication status classifications2010In: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 60, no 6, p. 919-924Article in journal (Refereed)
    Abstract [en]

    We report the development of a methodology for assessing confidence in ecological status classifications. The method presented here can be considered as a secondary assessment, supporting the primary assessment of eutrophication or ecological status. The confidence assessment is based on scoring the quality of the indicators on which the primary assessment is made. This represents a first step towards linking status classification with information regarding their accuracy and precision. Applied to an existing data set used for assessment of eutrophication status of the Baltic Sea (including the Kattegat and Danish Straits) we demonstrate that confidence in the assessment is Good or High in 149 out of 189 areas assessed (79%). Contrary to our expectations, assessments of the open parts of the Baltic Sea have a higher confidence than assessments of coastal waters. We also find that in open waters of the Baltic Sea, some biological indicators have a higher confidence than indicators representing physical-chemical conditions. In coastal waters, phytoplankton, submerged aquatic vegetation and indicators of physical-chemical conditions have a higher confidence than indicators of the quality of benthic invertebrate communities. Our analyses also show that the perceived weaknesses of eutrophication assessments are due more to Low confidence in reference conditions and acceptable deviations, rather than in the monitoring data. (C) 2010 Elsevier Ltd. All rights reserved.

  • 191.
    Almroth-Rosell, Elin
    et al.
    SMHI, Research Department, Oceanography.
    Skogen, Morten D.
    A North Sea and Baltic Sea Model Ensemble Eutrophication Assessment2010In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 39, no 1, p. 59-69Article in journal (Refereed)
    Abstract [en]

    A method to combine observations and an ensemble of ecological models is suggested to produce a eutrophication assessment. Using threshold values and methodology from the Oslo and Paris Commissions (OSPAR) and the Helsinki Commission (HELCOM), four models are combined to assess eutrophication for the Baltic and North Seas for the year 2006. The assessment indicates that the entire southeastern part of the North Sea, the Kattegat, the Danish Straits, the Gulf of Finland, and the Gulf of Riga as well as parts of the Arkona Basin, the Bornholm Basin, and the Baltic proper may be classified as problem areas. The Bothnian Bay and parts of the Baltic proper, the Bornholm Basin, and the Arkona Basin are classified as potential problem areas. This method is a useful tool for the classification of eutrophication; however, the results depend on the threshold values, and further work is needed within both OSPAR and HELCOM to harmonize these values.

  • 192. Myrberg, Kai
    et al.
    Ryabchenko, Vladimir
    Isaev, Alexei
    Vankevich, Roman
    Andrejev, Oleg
    Bendtsen, Jorgen
    Erichsen, Anders
    Funkquist, Lennart
    SMHI, Research Department, Oceanography.
    Inkala, Arto
    Neelov, Ivan
    Rasmus, Kai
    Medina, Miguel Rodriguez
    Raudsepp, Urmas
    Passenko, Jelena
    Soederkvist, Johan
    Sokolov, Alexander
    Kuosa, Harri
    Anderson, Thomas R.
    Lehmann, Andreas
    Skogen, Morten D.
    Validation of three-dimensional hydrodynamic models of the Gulf of Finland2010In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 15, no 5, p. 453-479Article in journal (Refereed)
    Abstract [en]

    A model-intercomparison study was conducted, the first of its kind for the Baltic Sea, whose aim was to systematically simulate the basic three-dimensional hydrographic properties of a realistic, complex basin. Simulations of the hydrographic features of the Gulf of Finland for the summer autumn of 1996 by six three-dimensional hydrodynamic models were compared. Validation was undertaken using more than 300 vertical hydrographic profiles of salinity and temperature. The analysis of model performance, including averaging of the ensemble results, was undertaken with a view to assessing the potential suitability of the models in reproducing the physics of the Baltic Sea accurately enough to serve as a basis for accurate simulations of biogeochemistry once ecosystem models are incorporated. The performance of the models was generally satisfactory. Nevertheless, all the models had some difficulties in correctly simulating vertical profiles of temperature and salinity, and hence mixed layer dynamics, particularly in the eastern Gulf of Finland. Results emphasized the need for high resolution in both vertical and horizontal directions in order to resolve the complex dynamics and bathymetry of the Baltic Sea. Future work needs to consider the choice of mixing and advection schemes, moving to higher resolution, high-frequency forcing, and the accurate representation of river discharges and boundary conditions.

  • 193.
    Hordoir, Robinson
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Freshwater fluxes in the Baltic Sea: A model study2010In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 115, article id C08028Article in journal (Refereed)
    Abstract [en]

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

  • 194.
    Löptien, Ulrike
    et al.
    SMHI, Research Department, Oceanography.
    Eden, Carsten
    Multidecadal CO2 uptake variability of the North Atlantic2010In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 115, article id D12113Article in journal (Refereed)
    Abstract [en]

    The multidecadal variability of air-sea CO(2)fluxes in the North Atlantic under preindustrial atmospheric CO2 conditions is simulated, using a coupled biogeochemical/circulation model driven by long-term surface forcing reconstructed from the leading modes of sea level pressure observations from 1850 to 2000. Heat fluxes are of great importance for the multidecadal CO2 fluctuations, about equal in magnitude to wind stress, in contrast to their less prominent role for CO2 flux variability on interannual timescales. Another difference, compared to higher frequencies, is the dominance of the North Atlantic Oscillation in driving the variability of the air-sea CO2 fluxes. Two spatially distinct regimes lead to large anomalies in the CO2 fluxes but compensate to a large degree. The first regime is advective and has its clear signature southeast of Greenland while the second one, in the vicinity of the Labrador Sea and off Newfoundland, is convective. In both regimes, the multidecadal CO2 fluctuations are driven mainly by variations in temperature, salinity, and DIC content at the sea surface while the role of the biological pump is of minor importance in this particular model. The magnitude of the simulated multidecadal CO2 uptake changes is on the order of 0.02 Pg C/yr and amounts to 10-15% of the estimated annual anthropogenic CO2 uptake of the North Atlantic.

  • 195.
    Meier, Markus
    et al.
    SMHI, Research Department, Oceanography.
    Bärring, Lars
    SMHI, Research Department, Climate research - Rossby Centre.
    Christensen, Ole Bössing
    Kjellström, Erik
    SMHI, Research Department, Climate research - Rossby Centre.
    Lorenz, Philip
    Rockel, Burkhardt
    Zorita, Eduardo
    Selected examples of the added value of regional climate models2009In: / [ed] Rockel, B., Bärring, L and Reckermann, M., 2009, p. 54-55Conference paper (Other academic)
  • 196.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    On the dynamics of organic nutrients, nitrogen and phosphorus, in the Baltic Sea2009Report (Other academic)
    Abstract [en]

    In this report we study the dynamics of organic nutrients, nitrogen and phosphorus, in the Baltic Sea. The results indicate that much of the characteristics of the surface layer dynamics of organic nutrients can be described by the Redfield ratio especially in the Baltic proper. There is however deviations from the Redfield ratio that are discussed and needs to be further investigated. The seasonal variations at all investigated stations indicate that the increase and decrease of the organic phosphorus and nitrogen concentrations in spring and autumn takes place with stoichiometric values different from the Redfield ratio. It is also found that organic phosphorus concentrations start to decrease earlier in summer than organic nitrogen that may continue to increase during summer and early autumn. There is a clear trend with decreasing DIN:DIP ratios in late winter at the Gotland Deep during the period 1995-2008 while there is an improved correlation of the Redfield model during the later part of the period when we have extremely low DIN:DIP ratios. Also the results from the Bothnian bay show that the variability of organic matter is fairly well described by the Redfield model despite the extremely high late winter N:P ratios observed in this region. Hence, the seasonal variability of organic matter seems to be rather independent of the ratio of inorganic nutrients. The variability of the inorganic N to P ratios in late winter and early spring across the Baltic Sea is much larger than seen from the variability of the organic matter. This suggests that other sources than DIN and DIP as sources for new nutrients in spring are used. This is true both in the Baltic proper, where an additional nitrogen source for organic matter production in spring is needed besides inorganic nitrogen, and in the Bothnian Bay, where an additional phosphorus source is needed. Nitrogen fixation by cyanobacteria that grow later in the summer in the southern Baltic Sea can not explain the additional nitrogen source needed in early spring. Future model experiments may reveal more information about the dynamics of organic matter in the Baltic Sea.

  • 197.
    Eilola, Kari
    et al.
    SMHI, Research Department, Oceanography.
    Sahlberg, Jörgen
    SMHI, Professional Services.
    Model assessment of the predicted environmental consequences for OSPAR problem areas following nutrient reductions2009Report (Other academic)
    Abstract [en]

    The Swedish Coastal and Ocean Biogeochemical model (SCOBI) is used for the assessment of eutrophication status in the Skagerrak and the Kattegat, and of the following long-term effects on the ecosystem for the 50% nutrient reduction target (PARCOM Recommendation 88/2). Model validation and the final reporting of the results in accordance with the OSPAR comprehensive procedure are presented.The model is validated by a comparison of a long time series (1985-2002) of the model results to data from a number of stations representing different parts of the model domain. A quantitative examination of the model performance is done by a comparison between the seasonal and annual averages of the model results and in-situ data. The model response to nutrient reductions shows that reducing nutrient inputs from land have the largest effects on the nitrate concentrations in the Kattegat and along the Swedish coast in the Skagerrak. The effects on phosphate concentrations are relatively small. The largest effect obtained from a 50% reduction of anthropogenic nitrogen and phosphorus from the runoff in one country alone is obtained for Sweden. This model experiment reduces the nitrate and chlorophyll concentrations in the Swedish coastal waters by 5%-10% and 3%-6%, respectively. The annual net production is reduced by 2%-4% and changes in sedimentation are less than 1%. The largest reduction is found in the Kattegat.The combined effect from a 50% reduction of anthropogenic nutrient supplies from land and an anticipated realistic reduction of nutrient concentrations in the Baltic Sea and the North Sea reduces the nitrate and phosphate concentrations in the Kattegat and the Swedish parts of the Skagerrak coastal area by 20%-30%. The average chlorophyll concentrations are reduced by 8%-11%. The annual net production and the sedimentation are reduced by 12%-20% and 5%-12%, respectively.

  • 198.
    Höglund, Anders
    et al.
    SMHI, Research Department, Oceanography.
    Meier, Markus
    SMHI, Research Department, Oceanography.
    Broman, Barry
    SMHI, Research Department, Climate research - Rossby Centre.
    Kriezi, Ekaterini
    SMHI.
    Validation and correction of regionalised ERA-40 wind fields over the Baltic Sea using the Rossby Centre Atmosphere model RCA3.02009Report (Other academic)
    Abstract [en]

    Surface wind fields from ERA-40 regionalised with the Rossby Centre Atmosphere model RCA3.0 are underestimated. In this report a method for correcting the wind fields is evaluated. The method is based on the empirical linear relationship between gusty winds and mean wind. For the validation observations from 26 automatic stations along the Swedish coasts have been used. We found that the validation of wind over the open sea is difficult due to the impact of land that cannot be resolved properly by the atmospheric model as the horizontal grid resolution amounts to about 25 km. In addition, long homogeneous wind data sets are not available due to a switch from manual to automatic readings during the 1990s. The results show that the correction method improves the frequency distribution of simulated wind speed at most stations. Thus the corrected wind fields may be used to force Baltic Sea models during 1961-2004. However, the suggested correction method should be regarded only as a temporary solution while waiting for improved boundary layer

  • 199.
    Karlson, Bengt
    et al.
    SMHI, Research Department, Oceanography.
    Axe, Philip
    SMHI, Research Department, Oceanography.
    Funquist, Lennart
    SMHI, Research Department, Oceanography.
    Kaitala, Seppo
    FIMR, Finnish Institute for Marine Research/SYKE Marine Centre.
    Sørensen, Kai
    NIVA, Norwegian Institute for Water Research.
    Infrastructure for marine monitoring and operational oceanography2009Report (Other academic)
    Abstract [en]

    Automated systems for observing physical, chemical and biological conditions in the sea are being implemented worldwide as part of the Global Ocean Observing System. This report describes their use in the Baltic and the Skagerrak-Kattegat areas. An evaluation of the use of FerryBox systems in the waters around Sweden shows that the quality of data from near surface waters is high, and that the frequent sampling makes possible observations of short term phenomena such as algal blooms. These events are often overlooked by infrequent sampling using research vessels, which leads to erroneous estimates of phytoplankton biomass, ecosystem carrying capacity etc. Data come from the Helsinki Lübeck route, operated by the Finnish Institute for Marine Research and from routes in the Skagerrak- Kattegat operated by the Norwegian Institute for Water Research. FerryBox data were compared with data from traditional sampling, principally from RV Argos operated by SMHI, but also from the HELCOM databank at ICES.Observations using automated systems such as satellites, stationary platforms (buoys and piles) and FerryBox systems may contribute substantially to improving the quality of results from models describing the physical and biogeochemical conditions in Scandinavian waters. Boundary conditions for models can be obtained using measurements in the eastern North Sea and in the Skagerrak, while data assimilation from a network of buoys, FerryBoxsystems and research vessels improves the quality of model results. Today, between four and six automated oceanographic observation systems are in operation in Swedish waters, which can be compared to more than 700 for meteorological purposes. A dramatic increase in the number of observations is necessary for effective data assimilation. To make the observations useful for biogeochemical models, parameters such as inorganic nutrients, phytoplankton biomass and oxygen must be added to the basic parameters salinity and temperature.A detailed proposal for a new infrastructure for marine monitoring and operational oceanography in Sweden is put forward. FerryBox systems should be operated in collaboration with institutes in Finland, Estonia, Poland, Germany, Denmark and Norway. Coastal buoys contribute to the monitoring needs of the EU Water Framework Directive while offshore buoys are for long term climate and ecological research and for fulfilment of the EU Marine Strategy Directive . Products combining satellite data with in-situ observations should be developed. These automated systems augment monitoring using research vessels but do not replace it. SMHI, the Swedish Institute for the Marine Environment, the Swedish Water Authorities, the Swedish Environmental Protection Agency, Swedish Navy, Coast guard, Maritime Administration and Board of Fisheries are proposed to govern and operate the system, with SMHI as the lead partner. The function -National data host for operational oceanographic data- is proposed, to be established at the National Oceanographic Data Centre at SMHI.A number of indicators for describing the status of the pelagic environment around Sweden are proposed. Some already exist while some are new. New ones include indicators for acidification, changes in plankton community structure and physical climate indicators. Basin wide indicators are based on measurements using a combination of sampling platforms. Other indicators are more specific, e.g. for transport between basins and inflow of water to the deep basins of the Baltic Proper.This report was commissioned by the Swedish National Environment Protection Agency

  • 200.
    Skogen, Morten
    et al.
    Havforskningsinstituttet, Norway.
    Søiland, H.
    Havforskningsinstituttet, Norway.
    Almroth, Elin
    SMHI, Research Department, Oceanography.
    Eilola, Kari
    SMHI, Research Department, Oceanography.
    Sehested Hansen, Ian
    DHI Water & Environment, Denmark.
    The year 2005: An environmental status report of the Skagerrak, Kattegat and the North Sea2009Report (Other academic)
    Abstract [en]

    This is the second year joint status report for the North Sea, Skagerrak and Kattegat area (Fig.1) carried out by SMHI, IMR and DHI as a part of the project BANSAI, supported by the Nordic Council of Ministers’ Sea and Air Group. The aim of the project is to integrate marine observations and ecological model simulations in an annual assessment of the Baltic and the North seas. The present report is mainly based on model estimates of some of the indicators suggested by the OSPAR Common Procedure (c.f. Appendix) for the identification of the eutrophication status of the maritime area (OSPAR, 2002 and 2003). This first joint report serve as a basis for the on-going discussions about the ecological quality indicators included in the assessment, and the way to merge results from different models and observations for the assessment.Estimations of river discharges and model results are used to describe the degree of nutrient enrichment (Category I) defined by the riverine loadings of nitrogen and phosphorus, and winter surface concentrations and ratios of DIN and DIP. The direct effects of nutrient enrichment during the growing season (Category II) are described in terms of the mean and maximum chlorophyll concentrations and model estimations of primary production. The ratio between diatoms and flagellates is used as an indicator of region specific phytoplankton indicator species (Category II). The indirect effects of nutrient enrichment (Category III) are discussed in terms of oxygen depletion in bottom waters. Estimations of region specific background concentrations and threshold values are gathered from the literature and used for the model assessment.The three model systems used for the joint assessment (Fig. 2) cover different parts of the North Sea, Skagerrak and the Kattegat area. Detailed descriptions of the models may be found on the websites presented below the figure.In section 2 the key messages from this assessment will be presented. In section 3, each country gives a brief observations overview for 2005 and some references to other sources and reports that might be useful for the readers. The methods of the assessment are described in section 4. Statistical characteristics of model results and in-situ data are presented in section 5 and the model assessment of eutrophication status is done in section 6. Conclusions and comments to the assessment are presented in section 7.

78910111213 181 - 200 of 374
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.7
|