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  • 1. Amir-Heidari, Payam
    et al.
    Arneborg, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Lindgren, J. Fredrik
    Lindhe, Andreas
    Rosen, Lars
    Raie, Mohammad
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Hassellov, Ida-Maja
    A state-of-the-art model for spatial and stochastic oil spill risk assessment: A case study of oil spill from a shipwreck2019Ingår i: Environment International, ISSN 0160-4120, E-ISSN 1873-6750, Vol. 126, s. 309-320Artikel i tidskrift (Refereegranskat)
  • 2.
    Arneborg, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Lensu, Mikko
    Ljungman, Olof
    Mattsson, Johan
    Oil drift modeling in pack ice - Sensitivity to oil-in-ice parameters2017Ingår i: Ocean Engineering, ISSN 0029-8018, E-ISSN 1873-5258, Vol. 144, s. 340-350Artikel i tidskrift (Refereegranskat)
  • 3.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    BSRA-15: A Baltic Sea Reanalysis 1990–20042013Rapport (Övrigt vetenskapligt)
    Abstract [en]

    Oceanographic observations are often of high quality but are available only with low resolution in time and space. On the other hand, model fields have high resolution in time and space but are not necessarily in agreement with observations. To bridge the gap between these very different kinds of data sets, a reanalysis can be made, which means that fixed versions of the numerical model and the data assimilation system are used to analyse a period of several years. This report describes an oceanographic reanalysis covering the period 1990 to 2004 (15 whole years). The horizontal resolution is 3 nautical miles in the Baltic Sea and 12 nautical miles in the North Sea, and the vertical resolution varies between 4 meters near the surface to 60 meters in the deepest part (up to 24 vertical layers). The time resolution of the reanalysis product is 6 hours. The numerical ocean model used is HIROMB (High-Resolution Operational Model for the Baltic), version 3.0. The data assimilation method used in this reanalysis is the Successive Corrections Method (SCM) for salinity and temperature, whereas ice observations in terms of ice charts were simply interpolated. The result looks good in terms of sea levels, ice fields, and salinity and temperature structure, whereas currents have not been validated. This oceanographic reanalysis was probably the first one ever for the Baltic Sea (when it was done in 2005) and may serve as a starting point before longer, more advanced reanalyses are produced.

  • 4.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    On the variability of Baltic Sea deepwater mixing1998Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, Vol. 103, nr C10, s. 21667-21682Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Historical oceanographic data from the period 1964-1997 from two deep subbasins (the Gotland Deep and the Landsort Deep) in the Baltic Sea have been analyzed, by using a budget method on stagnant periods, with respect to vertical diffusion and vertical energy flux density in the deep water. It was found that the rate of deepwater mixing varied with the seasons, with higher rates in fall and winter compared to spring and summer. Further, according to the analyzed data, the downward flux density of energy available for vertical diffusion decreased with increasing depth in the Gotland Deep. In the Landsort Deep, however, the flux density increased somewhat, probably because of topographic concentration of the energy, before decreasing toward the bottom. Moreover, the vertical energy flux densities were compared with the expected flux density from the local wind. It is proposed that in the Gotland Deep, which is outside the coastal boundary layer, the observed deepwater mixing is dominated by the energy input from the wind via inertial currents and internal waves. In the Landsort Deep, however, which is within the coastal boundary layer, the expected flux density of energy from the local wind cannot explain the observed rate of work against the buoyancy forces. It is proposed that the active coastal boundary layer plays a central role in the transfer of energy to mixing processes in the deep water.

  • 5.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Wind-driven internal waves and Langmuir circulations in a numerical ocean model of the southern Baltic Sea2002Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 107, nr C11, artikel-id 3204Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    [1] A one-dimensional numerical ocean model of the southern Baltic Sea is used to investigate suitable parameterizations of unresolved turbulence and compare with available observations. The turbulence model is a k-epsilon model that includes extra source terms P-IW and P-LC of turbulent kinetic energy (TKE) due to unresolved, breaking internal waves and Langmuir circulations, respectively. As tides are negligible in the Baltic Sea, topographic generation of internal wave energy (IWE) is neglected. Instead, the energy for deepwater mixing in the Baltic Sea is provided by the wind. At each level the source term P-IW is assumed to be related to a vertically integrated pool of IWE, E-0, and the buoyancy frequency N at the same level, according to P-IW (z) proportional to E0Ndelta (z). This results in vertical profiles of epsilon (the dissipation rate of TKE) and K-h (the eddy diffusivity) according to epsilon proportional to N-delta and K-h proportional to Ndelta-2 below the main pycnocline. Earlier observations are inconclusive as to the proper value of delta, and here a range of values of delta is tested in hundreds of 10-year simulations of the southern Baltic Sea. It is concluded that delta = 1.0 +/- 0.3 and that a mean energy flux density to the internal wave field of about (0.9 +/- 0.3) x 10(-3) W m(-2) is needed to explain the observed salinity field. In addition, a simple wind-dependent formulation of the energy flux to the internal wave field is tested, which has some success in describing the short- and long-term variability of the deepwater turbulence. The model suggests that similar to16% of the energy supplied to the surface layer by the wind is used for deepwater mixing. Finally, it is also shown that Langmuir circulations are important to include when modeling the oceanic boundary layer. A simple parameterization of Langmuir circulations is tuned against large-eddy simulation data and verified for the Baltic Sea.

  • 6.
    Axell, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Application of 3-D ensemble variational data assimilation to a Baltic Sea reanalysis 1989-20132016Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 68, artikel-id 24220Artikel i tidskrift (Refereegranskat)
    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.

  • 7.
    Axell, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Ljungman, Olof
    SMHI, Forskningsavdelningen, Oceanografi.
    A One-Equation Turbulence Model for Geophysical Applications: Comparison with Data and the k - epsilon Model2001Ingår i: Environmental Fluid Mechanics, ISSN 1567-7419, E-ISSN 1573-1510, Vol. 1, nr 1, s. 71-106Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A one-equation turbulence model is presented, in which the turbulent kinetic energy k is calculated with a transport equation whereas the turbulent length scale l is calculated with an algebraic expression. The value of l depends on the local stratification and reduces to the classical kappa vertical bar z vertical bar scaling for unstratified flows near a wall, where vertical bar z vertical bar is the distance to the wall. The length scale decreases during stable stratification, and increases for unstable stratification compared to the neutral case. In the limit of strong stable stratification, the so-called buoyancy length scale proportional to k(1/2)N(-1) is obtained, where N is the buoyancy frequency. The length scale formulation introduces a single model parameter which is calibrated against experimental data. The model is verified extensively against laboratory measurements and oceanic data, and comparisons are made with the two-equation k-epsilon model. It is shown that the performance of the proposed k model is almost identical to that of the k-epsilon model. In addition, the stability functions of Launder are revisited and adjusted to obtain better agreement with recent data.

  • 8.
    Dieterich, Christian
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Wang, Shiyu
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Klein, Birgit
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Surface Heat Budget over the North Sea in Climate Change Simulations2019Ingår i: Atmosphere, ISSN 2073-4433, E-ISSN 2073-4433, Vol. 10, nr 5, artikel-id 272Artikel i tidskrift (Refereegranskat)
  • 9. Golbeck, Inga
    et al.
    Li, Xin
    Janssen, Frank
    Bruening, Thorger
    Nielsen, Jacob W.
    Huess, Vibeke
    Soderkvist, Johan
    Buchmann, Bjarne
    Siiria, Simo-Matti
    Vaha-Piikkio, Olga
    Hackett, Bruce
    Kristensen, Nils M.
    Engedahl, Harald
    Blockley, Ed
    Sellar, Alistair
    Lagemaa, Priidik
    Ozer, Jose
    Legrand, Sebastien
    Ljungemyr, Patrik
    SMHI, Samhälle och säkerhet.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Uncertainty estimation for operational ocean forecast products-a multi-model ensemble for the North Sea and the Baltic Sea2015Ingår i: Ocean Dynamics, ISSN 1616-7341, E-ISSN 1616-7228, Vol. 65, nr 12, s. 1603-1631Artikel i tidskrift (Refereegranskat)
    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.

  • 10.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Fransner, Filippa
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Pemberton, Per
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Ljungemyr, Patrik
    SMHI, Samhälle och säkerhet.
    Nygren, Petter
    SMHI, Samhälle och säkerhet.
    Falahat, Saeed
    SMHI, Samhälle och säkerhet.
    Nord, Adam
    SMHI, Samhälle och säkerhet.
    Jönsson, Anette
    SMHI, Samhälle och säkerhet.
    Lake, Irene
    SMHI, Samhälle och säkerhet. SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doos, Kristofer
    Hieronymus, Magnus
    SMHI, Forskningsavdelningen, Oceanografi.
    Dietze, Heiner
    Loeptien, Ulrike
    Kuznetsov, Ivan
    Westerlund, Antti
    Tuomi, Laura
    Haapala, Jari
    Nemo-Nordic 1.0: a NEMO-based ocean model for the Baltic and North seas - research and operational applications2019Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 12, nr 1, s. 363-386Artikel i tidskrift (Refereegranskat)
  • 11.
    Hordoir, Robinson
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Löptien, Ulrike
    SMHI, Forskningsavdelningen, Oceanografi.
    Dietze, Heiner
    Kuznetsov, Ivan
    SMHI, Forskningsavdelningen, Oceanografi.
    Influence of sea level rise on the dynamics of salt inflows in the Baltic Sea2015Ingår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 120, nr 10, s. 6653-6668Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 12. Kotovirta, Ville
    et al.
    Jalonen, Risto
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Riska, Kaj
    Berglund, Robin
    A system for route optimization in ice-covered waters2009Ingår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 55, nr 1, s. 52-62Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Information about ice is indispensable to navigation in ice-covered sea areas. For vessels traveling long distances in ice, it is worth planning routes that will reduce fuel consumption and travel time, as well as the risk of ending up in hazardous areas or getting stuck in the ice. In addition to observations on board. there is a multitude of data sources available for seafarers like satellite images, ice model data, weather observations and forecasts. However, it is difficult for a human to take into consideration all the time-varying data parameters when planning a route. In this paper, a prototype system for optimizing routes through the ice field is presented. The system integrates state-of-the-art ice modeling, ship transit modeling, and an enduser system as a route optimization tool for vessels navigating in ice-covered waters. The system has recently been validated on board merchant vessels in the Baltic Sea, and the system's performance has been analyzed statistically using AIS data. Based on the AIS data analysis the mean relative error of the estimated transit time was 0.144 [s/s] with a standard deviation of 0.147 [s/s] for long routes (90-650 km), and 0.018 [s/s] with standard deviation of 0.193 [s/s] for 50 km route segments. (C) 2008 Elsevier B.V. All rights reserved.

  • 13.
    Kuznetsov, Ivan
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Model study on the variability of ecosystem parameters in the Skagerrak-Kattegat area, effect of load reduction in the North Sea and possible effect of BSAP on Skagerrak-Kattegat area2016Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Den nyligen utvecklade ekosystemmodellen NEMO-Nordic-SCOBI användes för att studera variabiliteten av några indikatorer för ekosystemet i Skagerrak- kattegatt området. Även två känslighetsstudier gjordes för att undersöka möjliga effekter av Baltic Sea Action Plan (BSAP) och en reduktion scenario av närsaltstillförsel på Skagerrak-Kattegatt området. Den utförda studien kan användas som underlag och stöd vid tolkningen av observationsdata inför utvärderingen ”Intermediate Assessments Eutrophication status assessment”. Jämförelsen mellan modelldata och observationer indikerar att modellens resultat är acceptabla. Modellerade ytvärden av salthalt, temperatur och löst fosfat (DIP) visar god överenskommelse med observerade värden. Samtidigt har modellresultaten avvikelser i vissa delområden vad gäller löst oorganiskt kväve (DIN) och löst kisel under vitertid. Dock visar modellen i sitt nuvarande tillstånd tillräckligt goda resultat för den aktuella studien. Resultaten från de två känslighetsstudierna visar en minskning av näringskoncentrationer i ytan under vintern i båda havsområdena. I Skagerrak är minskningen orsakad av reducerad närsaltstillförsel i Nordsjön. I Kattegatt minskar lösta fosfatet på grund av genomförandet av BSAP. Ingen av scenarierna visade någon signifikant påverkan på syre vid havsbotten eller på ytkoncentratiner av Chl-a.

  • 14.
    Liu, Ye
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Reanalyzing temperature and salinity on decadal time scales using the ensemble optimal interpolation data assimilation method and a 3D ocean circulation model of the Baltic Sea2013Ingår i: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS, ISSN 2169-9275, Vol. 118, nr 10, s. 5536-5554Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A 30-year (1970-1999) reanalysis of temperature and salinity is conducted by assimilating temperature and salinity profiles into an ocean model of the Baltic Sea with ensemble optimal interpolation approach. Some configurations of the reanalysis are presented. For example, the samples are chosen from the same season as the analysis time to address the strong seasonal variability. The impact of different observation time windows on the analysis results is also discussed. A locally determined alpha is adopted for the long-time-scale simulation. To assess the accuracy of the reanalysis, a set of comparisons between the reanalysis results and the free run results was performed. The root mean square deviations (RMSDs) between the reanalysis results and not-yet-assimilated observations at all levels show that, compared to the free run, temperature and salinity have been improved significantly, that is, by 31.1 and 38.8%, respectively. The vertical structure of the reanalyzed fields is also adjusted. The reanalysis results show that the improvements in both temperature and salinity are smaller at greater water depths. Comparison with independent CTD data, the reanalysis significantly improved temperatures and salinities in all layers relative to the free run. For temperature and salinity during the period of ship voyages, the RMSDs are reduced by 32.9 and 25.5%, respectively. The temporal variations of the deep-water salinity caused by saltwater inflows are better captured by the reanalysis than by the free run. Moreover, the reanalysis improved the estimation of the depth of the halocline and thermocline, which are overestimated in the simulation without data assimilation.

  • 15. Löptien, Ulrike
    et al.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Ice and AIS: ship speed data and sea ice forecasts in the Baltic Sea2014Ingår i: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 8, nr 6, s. 2409-2418Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Baltic Sea is a seasonally ice-covered marginal sea located in a densely populated area in northern Europe. Severe sea ice conditions have the potential to hinder the intense ship traffic considerably. Thus, sea ice fore-and nowcasts are regularly provided by the national weather services. Typically, the forecast comprises several ice properties that are distributed as prognostic variables, but their actual usefulness is difficult to measure, and the ship captains must determine their relative importance and relevance for optimal ship speed and safety ad hoc. The present study provides a more objective approach by comparing the ship speeds, obtained by the automatic identification system (AIS), with the respective forecasted ice conditions. We find that, despite an unavoidable random component, this information is useful to constrain and rate fore-and nowcasts. More precisely, 62-67% of ship speed variations can be explained by the forecasted ice properties when fitting a mixed-effect model. This statistical fit is based on a test region in the Bothnian Sea during the severe winter 2011 and employs 15 to 25 min averages of ship speed.

  • 16. Nilsson, Erik
    et al.
    Rutgersson, Anna
    Dingwell, Adam
    Bjorkqvist, Jan-Victor
    Pettersson, Heidi
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Nyberg, Johan
    Stromstedt, Erland
    Characterization of Wave Energy Potential for the Baltic Sea with Focus on the Swedish Exclusive Economic Zone2019Ingår i: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, nr 5, artikel-id 793Artikel i tidskrift (Refereegranskat)
  • 17.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Fourth Workshop on Baltic Sea Ice Climate. Norrköping, Sweden 22-24 May, 2002. Conference Proceedings2001Rapport (Övrigt vetenskapligt)
  • 18.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Modeling the seasonal, interannual, and long-term variations of salinity and temperature in the Baltic proper1998Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 50, nr 5, s. 637-652Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Salinity and temperature variations in the Baltic proper and the Kattegat have been analyzed with a numerical ocean model and a large amount of observational data. In the model, the Baltic Sea is divided into 13 sub-basins with high vertical resolution, horizontally coupled by barotropic and baroclinic flows and vertically coupled to a sea-ice model which includes dynamics as well as thermodynamics. The model was integrated for a 15-year period (1980-1995) by using observed meteorological forcing data, river-runoff data and sea-level data from the Kattegat. The calculated 15-year median profiles of salinity and temperature in the different sub-basins are in good agreement with observations. However, the calculated mid-depth salinities in the Arkona Basin and Bornholm Basin were somewhat overestimated, and the calculated deep-water temperatures in the Arkona Basin and the Bornholm Basin are somewhat lower than the observed values. Frontal mixing and movements in the Kattegat and the entrance area of the Arkona Basin were important to consider in the model. Water masses were simulated well, and prescribing constant deep-water properties in the Kattegat proved to be a reasonable lateral boundary condition. Further, comparisons were made between observed and calculated seasonal and interannual variations of the hydrographic properties in the Eastern Gotland Basin, as well as the interannual variations of the annual maximum ice extent. We conclude that the model can simulate these variations realistically. The major Baltic inflow of 1993 was also simulated by the model, but the inflowing water was 1-2 degrees degrees too cold. Finally, the response times to changes in forcing of the Baltic proper and the Kattegat were investigated by performing the so-called lock-exchange experiment. Typical stratification spin-up times were of the order of 10 years for the Kattegat, and 100 years for the Baltic proper.

  • 19.
    Omstedt, Anders
    et al.
    Göteborgs Universitet.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Modeling the variations of salinity and temperature in the large Gulfs of the Baltic Sea2003Ingår i: Continental Shelf Research, ISSN 0278-4343, E-ISSN 1873-6955, Vol. 23, nr 3-4, s. 265-294Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The modeling of salinity and temperature in Gulf of Bothnia, Gulf of Finland, and Gulf of Riga is investigated by using a coupled sea ice-ocean Baltic Sea model. 18 years, from late 1980 to the end of 1998, have been investigated. The forcing data extracted taken from a gridded meteorological data base, sea level data from the Kattegat, and river runoff data to the different subbasins of the Baltic Sea from a hydrological data base. To improve the gridded meteorological data base a statistical model for the reduction of geostrophic winds to surface winds was developed. In the analysis it was shown that the calculated long-term salinity and temperature structures were stable and in good agreement with observations. This was made possible by using three different strait-flow models connecting the subbasins of the Baltic Sea. The seasonal and interannual variations of temperature and salinity were also well simulated by the model, implying that the coupling between the atmosphere and the Baltic Sea as well as the diapycnal mixing are reasonably well understood. The water cycle and the surface heat balance were calculated using the 18-year simulation. In the water-balance calculations it was shown that the volume flows from the large gulfs of the Baltic Sea were mainly due to baroclinic transports and that net precipitation added freshwater during the Studied period, particularly to the large gulfs. From the heat-balance calculation it is concluded that the Baltic Sea is almost in local balance with the atmosphere. The Bothnian Bay, Gulf of Finland and Gulf of Riga loose heat, whereas the Bothnian Sea gains heat, calculated as long-term means. (C) 2003 Elsevier Science Ltd. All rights reserved.

  • 20.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Löptien, Ulrike
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
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    SMHI, Forskningsavdelningen, Oceanografi.
    Schimanke, Semjon
    SMHI, Forskningsavdelningen, Oceanografi.
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Haapala, Jari
    Sea-ice evaluation of NEMO-Nordic 1.0: a NEMO-LIM3.6-based ocean-sea-ice model setup for the North Sea and Baltic Sea2017Ingår i: Geoscientific Model Development, ISSN 1991-959X, E-ISSN 1991-9603, Vol. 10, nr 8, s. 3105-3123Artikel i tidskrift (Refereegranskat)
  • 21. von Schuckmann, Karina
    et al.
    Le Traon, Pierre-Yves
    Alvarez-Fanjul, Enrique
    Axell, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Balmaseda, Magdalena
    Breivik, Lars-Anders
    Brewin, Robert J. W.
    Bricaud, Clement
    Drevillon, Marie
    Drillet, Yann
    Dubois, Clotilde
    Embury, Owen
    Etienne, Hélène
    Sotillo, Marcos García
    Garric, Gilles
    Gasparin, Florent
    Gutknecht, Elodie
    Guinehut, Stéphanie
    Hernandez, Fabrice
    Juza,, Melanie
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Korres, Gerasimos
    Legeais, Jean-François
    Levier, Bruno
    Lien, Vidar S.
    Morrow, Rosemary
    Notarstefano, Giulio
    Parent, Laurent
    Pascual, Álvaro
    PérezGómez, Begoña
    Perruche, Coralie
    Pinardi, Nadia
    Pisano, Andrea
    Poulain, Pierre-Marie
    Pujol, Isabelle M.
    Raj, Roshin P.
    Raudsepp, Urmas
    Roquet, Hervé
    Samuelsen, Annette
    Sathyendranath, Shubha
    She, Jun
    Simoncelli, Simona
    Cosimo, Solidoro
    Tinker, Jonathan
    Tintoré, Joaquín
    Viktorsson, Lena
    SMHI, Samhälle och säkerhet.
    Ablain, Michael
    Almroth-Rosell, Elin
    SMHI, Forskningsavdelningen, Oceanografi.
    Bonaduce, Antonio
    Clementi, Emanuela
    Cossarini, Gianpiero
    Dagneaux, Quentin
    Desportes, Charles
    Dye, Stephen
    Fratianni, Claudia
    Good, Simon
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    Gourrion, Jerome
    Hamon, Mathieu
    Holt, Jason
    Hyder, Pat
    Kennedy, John
    ManzanoMuñoz, Fernando
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    Meyssignac, Benoit
    Mulet, Sandrine
    Buongiorno Nardelli, Bruno
    O´Dea, Enda
    Olason, Einar
    Paulmier, Aurélien
    Pérez-González, Irene
    Reid, Rebecca
    Racault, Marie-Fanny
    Raitsos, Dionysios E.
    Ramos,, Antonio
    Sykes, Peter
    Szekely, Tanguy
    Verbrugge, Nathalie
    The Copernicus Marine Environment Monitoring Service Ocean State Report2017Ingår i: Journal of operational oceanography. Publisher: The Institute of Marine Engineering, Science & Technology, ISSN 1755-876X, E-ISSN 1755-8778, Vol. 9, nr Sup.2, s. 235-320Artikel i tidskrift (Refereegranskat)
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