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  • 301.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Sahlberg, Jörgen
    SMHI, Affärsverksamhet.
    Some results from a joint Swedish-Finnish sea ice experiment, March, 19771978Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Ett gemensamt svensk-finskt havsisexperiment genomfördes under mars 1977. Mätningar i atmosfären, isen och havet utfördes under sex dagar ombord på det finska forskningsfartyget Aranda som var placerad i isfältet i Bottenviken. Under två dagar utfördes även mätningar från de två svenska isbrytarna Atle och Tor. Denna rapport presenterar data och några resultat från svenska gruppen.

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  • 302.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Svensson, Urban
    SMHI, Forskningsavdelningen, Oceanografi.
    ON THE MELT RATE OF DRIFTING ICE HEATED FROM BELOW1992Ingår i: Cold Regions Science and Technology, ISSN 0165-232X, E-ISSN 1872-7441, Vol. 21, nr 1, s. 91-100Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The melt rates of fresh and saline drifting ice, heated from below, are examined using a one-dimensional ice/ocean model with high vertical resolution. The model is based on the conservation equations for heat, salt, and momentum and uses turbulence models to achieve closure. The model includes a low-Reynolds number turbulence model for the viscous region, coupled to a high-Reynolds number turbulence model for the outer boundary, and a discrete element approach to the parameterization of roughness. It is shown that the melt rate of drifting ice is sensitive to ice roughness and molecular salt diffusion, and it is found that bulk heat transfer coefficients vary within a rather narrow range in the examined interval.

  • 303.
    Omstedt, Anders
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    WETTLAUFER, JS
    ICE GROWTH AND OCEANIC HEAT-FLUX - MODELS AND MEASUREMENTS1992Ingår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 97, nr C6, s. 9383-9390Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Heat fluxes al the ice-ocean interface and ice thickness are investigated by comparing field data from the Coordinated Eastern Arctic Experiment (CEAREX) drift phase with model calculations. The calculations are based on two types of models. The first one is a one-dimensional ice-ocean model with high vertical resolution. This model is based on the conservation equations for heat, salt, and momentum and uses turbulence models to achieve closure. A discrete element approach is also introduced to explicitly parameterize the ice roughness. The second model is a simple one-dimensional bulk heat transfer model. In this version, the interfacial salinity is modelled on the basis of salt conservation at the ice-ocean interface. The bulk heat transfer model is then calibrated using the former model. The two models predict ocean heat fluxes that are quite variable in time owing to short-term variations in the ice drift. Both models calculate realistic ice thicknesses. It is demonstrated that the observed time variation in ice thickness from eight different experimental sites with varying initial thicknesses and bottom topographies can be reproduced by applying bulk heat transfer coefficients in the range (2.8 +/- 1) x 10(-4). Horizontal variation of the thermal state within a single pack ice floe results in simultaneous freezing and melting over relatively small spatial scales. When modeling or averaging ice data in space these aspects need to be considered.

  • 304. Paczkowska, J.
    et al.
    Rowe, Of
    Schluster, L.
    Legrand, C.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, A.
    Allochthonous matter: an important factor shaping the phytoplankton community in the Baltic Sea2017Ingår i: Journal of Plankton Research, ISSN 0142-7873, E-ISSN 1464-3774, Vol. 39, nr 1, s. 23-34Artikel i tidskrift (Refereegranskat)
  • 305. Paetsch, Johannes
    et al.
    Burchard, Hans
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Graewe, Ulf
    Gröger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Mathis, Moritz
    Kapitza, Hartmut
    Bersch, Manfred
    Moll, Andreas
    Pohlmann, Thomas
    Su, Jian
    Ho-Hagemann, Ha T. M.
    Schulz, Achim
    Elizalde, Alberto
    Eden, Carsten
    An evaluation of the North Sea circulation in global and regional models relevant for ecosystem simulations2017Ingår i: Ocean Modelling, ISSN 1463-5003, E-ISSN 1463-5011, Vol. 116, s. 70-95Artikel i tidskrift (Refereegranskat)
  • 306.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Löptien, Ulrike
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    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)
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  • 307.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Nilsson, J.
    The response of the central Arctic Ocean stratification to freshwater perturbations2016Ingår i: Journal of Geophysical Research - Oceans, ISSN 2169-9275, E-ISSN 2169-9291, Vol. 121, nr 1, s. 792-817Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 308.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Nilsson, Johan
    Hieronymus, Magnus
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Arctic Ocean Water Mass Transformation in S-T Coordinates2015Ingår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 45, nr 4, s. 1025-1050Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

  • 309.
    Pemberton, Per
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Nilsson, Johan
    SMHI, Samhälle och säkerhet.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Arctic Ocean freshwater composition, pathways and transformations from a passive tracer simulation2014Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 66Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Freshwater (FW) induced transformations in the upper Arctic Ocean were studied using a coupled regional sea ice-ocean model driven by winds and thermodynamic forcing from a reanalysis of data during the period 1948-2011, focusing on the mean state during 1968-2011. Using passive tracers to mark a number of FW sources and sinks, their mean composition, pathways and export were examined. The distribution of the simulated FW height reproduced the known features of the Arctic Ocean and volume-integrated FW content matched climatological estimates reasonably well. Input from Eurasian rivers and extraction by sea-ice formation dominate the composition of the Arctic FW content whilst Pacific water increases in importance in the Canadian Basin. Though pathways generally agreed with previous studies the locus of the Eurasian runoff shelf-basin transport centred at the Alpha-Mendeleyev ridge, shifting the Pacific-Atlantic front eastwards. A strong coupling between tracers representing Eurasian runoff and sea-ice formation showed how water modified on the shelf spreads across the Arctic and mainly exits through the Fram Strait. Transformation to salinity dependent coordinates showed how Atlantic water is modified by both low-salinity shelf and Pacific waters in an estuary-like overturning producing water masses of intermediate salinity that are exported to the Nordic Seas. A total halocline renewal rate of 1.0 Sv, including both shelf-basin exchange and cross-isohaline flux, was estimated from the transports: both components were of equal magnitude. The model's halocline shelf-basin exchange is dominated by runoff and sea-ice processes at the western shelves (the Barents and Kara seas) and Pacific water at the eastern shelves (the Laptev, East Siberian and Chukchi seas).

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  • 310.
    Pers, Charlotta
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Jonsson, A
    Bergstrom, A K
    Jansson, M
    Modelling dissolved organic carbon turnover in humic Lake Ortrasket, Sweden2001Ingår i: Environmental Modelling and Assessment, ISSN 1420-2026, E-ISSN 1573-2967, Vol. 6, nr 3, s. 159-172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The organic carbon balance of a lake with high input of allochthonous organic carbon is modelled integrating physical, chemical and biological processes. The physical model captures the behaviour of real thermal stratification in the lake for different flow situations during the period 1993-1997. The dissolved organic carbon model is based on simulated trajectories of water parcels. By tracking parcels, account is kept of environmental factors such as temperature and radiation as well as DOC quality for each parcel, The DOC concentration shows seasonal variations primarily dependent on inflow. The organic matter degradation (bacterial- and photodegradation) in the lake amounts to 1.5-2.5 mg C l(-1) yr(-1), where photooxidation is responsible for approximately 10%. The estimated DIC production in the lake is large compared to sediment mineralisation and primary production. The main conclusion is that the model with the selected parameterisations of the degradation processes reasonably well describes the DOC dynamics in a forest lake.

  • 311.
    Persson, Christer
    et al.
    SMHI, Forskningsavdelningen, Luftmiljö.
    Funquist, Lennart
    SMHI, Forskningsavdelningen, Oceanografi.
    Local scale plume model for nitrogen oxides: Model description1984Rapport (Övrigt vetenskapligt)
  • 312.
    Persson, Gunn
    et al.
    SMHI, Affärsverksamhet.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Andréasson, Johan
    SMHI, Affärsverksamhet.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Impact of Climate Change Effects on Sea-Level Rise in Combination with an Altered River Flow in the Lake Mälar Region: Conference Proceedings2004Ingår i: Fourth Study Conference on BALTEX: Conference Proceedings / [ed] Hans-Jörg Isemer, 2004, s. 172-173Konferensbidrag (Övrigt vetenskapligt)
  • 313.
    Persson, Tomas
    SMHI, Forskningsavdelningen, Oceanografi.
    Solar radiation climate in Sweden1999Ingår i: Physics and chemistry of the earth. Part B: Hydrology, oceans and atmosphere, ISSN 1464-1909, E-ISSN 1873-4677, Vol. 24, nr 3, s. 275-279Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Since 1983 a Swedish network of 12 solar radiation stations, measuring global radiation, G, and direct normal irradiance, EN, is Operated by SMHI. All stations are sited within the BALTEX area. During the fifteen years 1983-1997, for which a homogeneous radiation database has been built up, some clear features in the radiation climate show up. The largest difference in G on annular basis is between the stations Visby, located on the island of Gotland in the Baltic Sea, and Kiruna, the northernmost station. The mean annual total of G in Kiruna (2822 MJm(-2)) is 25 % less than in Visby (3758 MJm(-2)). This is due to both latitudinal effects and differing cloud conditions. The effect of different cloudiness is clearly seen when comparing the stations Vaxjo and Visby, which are only separated by 0.74 degrees in latitude. At the cloudier site in Vaixjo, G is on the average 12 % less than in Visby. At all stations there is a large year to year variation of 15 %, or more. During the period analysed there is a clear increasing trend in both G, EN and duration of bright sunshine at all stations. The trend in G averaged over all stations is + 7.2 %/decade. This is mainly caused by decreasing cloudiness, especially during the summer months. Taking the atmospheric water vapour into account, the (A) over circle ngstrom turbidity coefficient, beta, have been estimated from the measurements of EN Mean values of beta during 1983-1997 are 0.082 in Lund (station with highest turbidity) and 0.056 in Kiruna (station with lowest turbidity). These values are strongly affected, approximately to the same extent, by the major volcanic eruptions of El Chichon and Mt. Pinatubo. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • 314. Petersen, W.
    et al.
    Colijn, F.
    Gorringe, Patrick
    SMHI, Samhälle och säkerhet.
    Kaitala, S.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    King, A.
    Lips, U.
    Ntoumas, M.
    Seppälä, J.
    Sørensen, K.
    Petihakis, G.
    De La Villéon, L.P.
    Wehde, H.
    FERRYBOXES WITHIN EUROPE: STATE-OF-THE-ART AND INTEGRATION IN THE EUROPEAN OCEAN OBSERVATION SYSTEM (EOOS)2017Ingår i: OPERATIONAL OCEANOGRAPHY: Serving Sustainable Marine Development / [ed] Erik Buch, Vicente Fernández, Dina Eparkhina, Patrick Gorringe and Glenn Nolan, EuroGOOS. Brussels, Belgium , 2017, s. 63-70Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    The development and use of FerryBox systems as a cost-effective instrument for continuous observations of the marine environment has been well established since more than 15 years. The systems have evolved to maturity and are since widely used around the coastal ocean of Europe. The availability of newly developed sensors allows the extension of FerryBox measurements to more biogeochemical parameters which are of interest for the requirements of the Marine Strategy Framework Directive (MSFD). The FerryBox community initially formed from the partners of an EU funded FerryBox project provides mutual exchange of experience and is now organized within EuroGOOS as a so called FerryBox Task Team (www.ferrybox.org). Within the EU funded infrastructure projects JERICO and JERICO-NEXT the technical harmonization as well as the developing of best practise guides for FerryBox systems have been a step further to high quality environmental data products. Within JERICO-NEXT it has been decided to build up a common FerryBox database and data portal in order to make the FerryBox data more available and visible. Furthermore this database will be function as a close link to the Copernicus Marine Environmental Monitoring Services (CMEMS) and the EMODnet portal.

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  • 315. Placke, Manja
    et al.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Graewe, Ulf
    Neumann, Thomas
    Frauen, Claudia
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Long-Term Mean Circulation of the Baltic Sea as Represented by Various Ocean Circulation Models2018Ingår i: Frontiers in Marine Science, E-ISSN 2296-7745, Vol. 5, artikel-id UNSP 287Artikel i tidskrift (Refereegranskat)
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  • 316. Prendergast, Gabrielle S.
    et al.
    Zurn, Constanze M.
    Bers, A. Valeria
    Head, Ritchie M.
    Hansson, Lars J.
    SMHI, Forskningsavdelningen, Oceanografi.
    Thomason, Jeremy C.
    Field-based video observations of wild barnacle cyprid behaviour in response to textural and chemical settlement cues2008Ingår i: Biofouling (Print), ISSN 0892-7014, E-ISSN 1029-2454, Vol. 24, nr 6, s. 449-459Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Many marine invertebrate larvae respond behaviourally to environmental settlement cues, yet behaviours are often only inferred from settlement patterns or are limited to laboratory studies. The behaviour of wild cypris larvae of Semibalanus balanoides L. was filmed on settlement tiles in the field. Tiles were of five different textures with a nested treatment of crude conspecific adult extract (AE). The effects of texture and AE on eleven defined behaviours were analysed. Texture affected the gross and net exploratory distances, velocity, acceleration and time spent exploring. AE attracted more cyprids during the first minute of immersion and increased the time spent on surfaces. Relatively few arrivals that either travel far and fast, or exit the surface rapidly, may indicate a lower chance of settlement. An increase in time spent on a surface may increase the probability of being in contact with the surface when the sign stimulus to settle occurs.

  • 317. Prendergast, Gabrielle S.
    et al.
    Zurn, Constanze M.
    Bers, A. Valeria
    Head, Ritchie M.
    Hansson, Lars J.
    SMHI, Forskningsavdelningen, Oceanografi.
    Thomason, Jeremy C.
    The relative magnitude of the effects of biological and physical settlement cues for cypris larvae of the acorn barnacle, Semibalanus balanoides L.2009Ingår i: Biofouling (Print), ISSN 0892-7014, E-ISSN 1029-2454, Vol. 25, nr 1, s. 35-44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Barnacle cypris larvae respond to many cues when selecting a settlement site. The settlement of over a million larvae on tiles of different textures, orientations and densities of incumbent settlers was measured on the rocky intertidal at Great Cumbrae, Scotland. Half of the tiles were replaced every tide whereas the others simultaneously accumulated settlers. Factor effects varied on each tide, and converged in the accumulating deployment. Increasing incumbent density led to net loss of settlement, which was less probable on the textures on which fastest settlment occurred ('very fine'), and more probable on those on which settlement was slowest ('smooth'). More settlement occurred on down-facing orientations during daylight and vice versa. Cue ranks were non-linear, so a path analysis model quantified the relative influence of each factor. Gregariousness was the most influential cue measured, although unmeasured factors had greater effects, highlighting the complexity of settlement influences in this species.

  • 318. Prevett, Andrew
    et al.
    Lindstrom, Jenny
    Xu, Jiayi
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Selander, Erik
    Grazer-induced bioluminescence gives dinoflagellates a competitive edge2019Ingår i: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 29, nr 12, s. R564-R565Artikel i tidskrift (Refereegranskat)
  • 319. Puillat, I
    et al.
    Carlier, A
    Facq, JV
    Rubio, A
    Lazure, P
    Delauney, L
    Petihakis, G
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Artigas, F
    Farcy, P
    DEPLOYMENT OF NEW OBSERVING SYSTEMS WITHIN THE JERICO-RI2017Ingår i: OPERATIONAL OCEANOGRAPHY: Serving Sustainable Marine Development, 2017, s. 43-51Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    A key message of the JERICO-RI consortium (2014): “The complexity of the coastal ocean cannot be well understood if interconnection between physics, biogeochemistry and biology is not guaranteed. Such integration requires new technological developments allowing continuous monitoring of a larger set of parameters”. In agreement with this consideration, several new observing systems are developed, tested and deployed in the framework of the JERICO-NEXT H2020 project, amongst which a few of them will be presented as well as some preliminary results after the first deployments. Focus will be given on coastal transports and hydrology and on benthic biodiversity. In the first case, we will present a low cost 2D moored system dedicated to acquire vertical temperature profiles in shallow waters and its application to study the high frequency hydrodynamics. In addition, during one of the campaigns foreseen for testing these new systems in an area covered by HF radar, hydrographic and current measurements in the water column, together with phytoplankton and plastic sampling, were conducted. In the second case, attention will be drawn on a new floating pulled system dedicated to observe benthic habitat without disturbing it.

  • 320. Puillat, I.
    et al.
    Farcy, P.
    Durand, D.
    Karlson, Bengt
    SMHI, Forskningsavdelningen, Oceanografi.
    Petihakis, G.
    Seppala, J.
    Sparnocchia, S.
    Progress in marine science supported by European joint coastal observation systems: The JERICO-RI research infrastructure2016Ingår i: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 162, s. 1-3Artikel i tidskrift (Refereegranskat)
  • 321.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    ON THE THERMAL ADJUSTMENT OF AN ALMOST-ENCLOSED FLUID REGION WITH THROUGH-FLOW1986Ingår i: International Journal of Heat and Mass Transfer, ISSN 0017-9310, E-ISSN 1879-2189, Vol. 29, nr 10, s. 1479-1485Artikel i tidskrift (Refereegranskat)
  • 322.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    OXYGEN-CONSUMPTION IN THE BALTIC PROPER1987Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 32, nr 4, s. 973-978Artikel i tidskrift (Refereegranskat)
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  • 323.
    Rahm, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Håkansson, Bertil
    SMHI, Forskningsavdelningen, Oceanografi.
    LARSSON, P
    FOGELQVIST, E
    BREMLE, G
    Valderaama, Jorge
    SMHI.
    NUTRIENT AND PERSISTENT POLLUTANT DEPOSITION ON THE BOTHNIAN BAY ICE AND SNOW FIELDS1995Ingår i: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 84, nr 1-2, s. 187-201Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A study of atmospheric deposited nutrients and some persistent pollutants has been carried out on the ice and snow fields of the subarctic Bothnian Bay, the northernmost basin of the Baltic Sea. Total amounts of 600, 500 and 400 tons NO3-N, NH4-N and N-org-N, respectively are deposited in the snow while the corresponding amounts for P-tot-P is 40 tons. The corresponding amount for PCB and lindane are 1.0 and 0.2 kg, respectively. The measurements were carried out on the snow-covered ice four to six weeks old. A part of the deposited snow has been incorporated into the snow-ice and an attempt to estimate its mean thickness and its amount of nutrients has been made. The total amounts now reach 1700, 1300 and 1100 tons of NO3-N and NH4-N and N-org-N, respectively in the snow and ice together. The results obtained support the use of land-based stations in estimates of seasonal atmospheric nutrient deposition to the Bothnian Bay. The observed concentrations of chloroorganic compounds correspond to those land-based observations reported from the same latitude in the northern hemisphere and reported in literature.

  • 324.
    Rahm, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Svensson, Urban
    SMHI, Forskningsavdelningen, Oceanografi.
    Dispersion in a stratified benthic boundary layer1989Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 41A, nr 2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A dispersion model for the stratified benthic boundary layer is formulated. It is based on "small-scale" vertical dispersion and a "large-scale" horizontal flow field. A modified Langevin equation governs the stochastic vertical migration of an ensemble of marked fluid elements. These elements are spread out by the horizontal flow, determined by a one-dimensional model, which includes a two-equation (k - epsilon) turbulence scheme. The later yields statistical information necessary for the stochastic process. Statistical properties of the dispersion process are then calculated from the evolution of the ensemble of elements. A rather idealized case with a linearly stratified fluid subject to a suddenly imposed barotropic pressure gradient is considered. A quasi-geostrophic interior flow is formed with a benthic boundary layer at the bottom. Marked fluid elements are released at the bottom and then followed for several pendulum days. It is found that the dispersion process is well characterized by K = Cu(*)l/(where u(*) and l are the friction velocity at the bottom and the layer thickness, respectively), and where C approximate to 15. A similar relation but based on external parameters only, becomes: K = C-b vertical bar partial derivative P/partial derivative y vertical bar(2)/rho(2) f(5/2) N-1/2, where C-b approximate to 0.11 in the range N/f = 28- 88

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  • 325.
    Rahm, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Svensson, Urban
    SMHI, Forskningsavdelningen, Oceanografi.
    DISPERSION OF MARKED FLUID ELEMENTS IN A TURBULENT EKMAN LAYER1986Ingår i: Journal of Physical Oceanography, ISSN 0022-3670, E-ISSN 1520-0485, Vol. 16, nr 12, s. 2084-2096Artikel i tidskrift (Refereegranskat)
  • 326.
    Rahm, Lars
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Svensson, Urban
    SMHI, Forskningsavdelningen, Oceanografi.
    ON THE MASS-TRANSFER PROPERTIES OF THE BENTHIC BOUNDARY-LAYER WITH AN APPLICATION TO OXYGEN FLUXES1989Ingår i: NETHERLANDS JOURNAL OF SEA RESEARCH, ISSN 0077-7579, Vol. 24, nr 1, s. 27-35Artikel i tidskrift (Refereegranskat)
  • 327. Raschke, E
    et al.
    Meywerk, J
    Warrach, K
    Andrae, Ulf
    SMHI, Forskningsavdelningen, Meteorologi.
    Bergström, Sten
    SMHI, Forskningsavdelningen, Hydrologi.
    Beyrich, F
    Bosveld, F
    Bumke, K
    Fortelius, C
    Graham, Phil
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Gryning, S E
    Halldin, S
    Hasse, L
    Heikinheimo, M
    Isemer, H J
    Jacob, D
    SMHI.
    Jauja, I
    Karlsson, Karl-Göran
    SMHI, Forskningsavdelningen, Atmosfärisk fjärranalys.
    Keevallik, S
    Koistinen, J
    van Lammeren, A
    Lass, U
    Launianen, J
    Lehmann, A
    Liljebladh, B
    Lobmeyr, M
    Matthaus, W
    Mengelkamp, T
    Michelson, Daniel
    SMHI, Samhälle och säkerhet.
    Napiorkowski, J
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Piechura, J
    Rockel, B
    Rubel, F
    Ruprecht, E
    Smedman, A S
    Stigebrandt, A
    The Baltic Sea Experiment (BALTEX): A European contribution to the investigation of the energy and water cycle over a large drainage basin2001Ingår i: Bulletin of The American Meteorological Society - (BAMS), ISSN 0003-0007, E-ISSN 1520-0477, Vol. 82, nr 11, s. 2389-2413Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The Baltic Sea Experiment (BALTEX) is one of the five continental-scale experiments of the Global Energy and Water Cycle Experiment (GEWEX). More than 50 research groups from 14 European countries are participating in this project to measure and model the energy and water cycle over the large drainage basin of the Baltic Sea in northern Europe. BALTEX aims to provide a better understanding of the processes of the climate system and to improve and to validate the water cycle in regional numerical models for weather forecasting and climate studies. A major effort is undertaken to couple interactively the atmosphere with the vegetated continental surfaces and the Baltic Sea including its sea ice. The intensive observational and modeling phase BRIDGE, which is a contribution to the Coordinated Enhanced Observing Period of GEWEX, will provide enhanced datasets for the period October 1999-February 2002 to validate numerical models and satellite products. Major achievements have been obtained in an improved understanding of related exchange processes. For the first time an interactive atmosphere-ocean-land surface model for the Baltic Sea was tested. This paper reports on major activities and some results.

  • 328. Raudsepp, Urmas
    et al.
    Uiboupin, Rivo
    Maljutenko, Ilja
    Hendricks, Stefan
    Ricker, Robert
    Liu, Ye
    SMHI, Forskningsavdelningen, Oceanografi.
    Iovino, Doroteaciro
    Peterson, K. Andrew
    Zuo, Hao
    Lavergne, Thomas
    Aaboe, Signe
    Raj, Roshin P.
    Combined analysis of Cryosat-2/SMOS sea ice thickness data with model reanalysis fields over the Baltic Sea2019Ingår i: Journal of operational oceanography. Publisher: The Institute of Marine Engineering, Science & Technology, ISSN 1755-876X, E-ISSN 1755-8778, Vol. 12, s. S73-+Artikel i tidskrift (Refereegranskat)
  • 329. Reckermann, Marcus
    et al.
    Langner, Joakim
    SMHI, Forskningsavdelningen, Luftmiljö.
    Omstedt, Anders
    Göteborgs Universitet.
    von Storch, Hans
    Keevallik, Sirje
    Schneider, Bernd
    Arheimer, Berit
    SMHI, Forskningsavdelningen, Hydrologi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Huenicke, Birgit
    BALTEX-an interdisciplinary research network for the Baltic Sea region2011Ingår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 6, nr 4, artikel-id 045205Artikel i tidskrift (Refereegranskat)
    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.

  • 330. Reusch, Thorsten B. H.
    et al.
    Dierking, Jan
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Bonsdorff, Erik
    Carstensen, Jacob
    Casini, Michele
    Czajkowski, Mikolaj
    Hasler, Berit
    Hinsby, Klaus
    Hyytiainen, Kari
    Johannesson, Kerstin
    Jomaa, Seifeddine
    Jormalainen, Veijo
    Kuosa, Harri
    Kurland, Sara
    Laikre, Linda
    MacKenzie, Brian R.
    Margonski, Piotr
    Melzner, Frank
    Oesterwind, Daniel
    Ojaveer, Henn
    Refsgaard, Jens Christian
    Sandstrom, Annica
    Schwarz, Gerald
    Tonderski, Karin
    Winder, Monika
    Zandersen, Marianne
    The Baltic Sea as a time machine for the future coastal ocean2018Ingår i: Science Advances, E-ISSN 2375-2548, Vol. 4, nr 5, artikel-id eaar8195Artikel i tidskrift (Refereegranskat)
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  • 331.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Graham, Phil
    SMHI, Affärsverksamhet.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Räisänen, Jouni
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willén, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    PRUDENCE-related regional climate modeling at the SMHI/Rossby Centre2002Ingår i: PRUDENCE kick-off meeting / [ed] Jens Hesselbjerg Christensen, Danish Climate Centre DMI, Ministry of Transport , 2002, s. 40-41Konferensbidrag (Övrigt vetenskapligt)
  • 332.
    Rummukainen, Markku
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Räisänen, Jouni
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bringfelt, Björn
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Willen, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, Ulf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    A regional climate model for northern Europe: model description and results from the downscaling of two GCM control simulations2001Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 17, nr 5-6, s. 339-359Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This work presents a regional climate model, the Rossby Centre regional Atmospheric model(RCA1), recently developed from the High Resolution Limited Area Model (HIRLAM). The changes in the HIRLAM parametrizations, necessary for climate-length integrations, are described. A regional Baltic Sea ocean model and a modeling system for the Nordic inland lake systems have been coupled with RCA1. The coupled system has been used to downscale 10-year time slices from two different general circulation model (GCM) simulations to provide high-resolution regional interpretation of large-scale modeling. A selection of the results from the control runs, i.e. the present-day climate simulations, are presented: large-scale free atmospheric fields, the surface temperature and precipitation results and results for the on-line simulated regional ocean and lake surface climates. The regional model modifies the surface climate description compared to the GCM simulations, but it is also substantially affected by the biases in the GCM simulations. The regional model also improves the representation of the regional ocean and the inland lakes, compared to the GCM results.

  • 333. Ruoho-Airola, Tuija
    et al.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    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 Data2012Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, nr 6, s. 549-557Artikel i tidskrift (Refereegranskat)
    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.

  • 334.
    Rutgersson, Anna
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Bumke, K
    Clemens, M
    Foltescu, Valentin
    SMHI.
    Lindau, R
    Michelson, Daniel
    SMHI, Samhälle och säkerhet.
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Precipitation estimates over the Baltic Sea: Present state of the art2001Ingår i: Nordic Hydrology, ISSN 0029-1277, E-ISSN 1996-9694, Vol. 32, nr 4-5, s. 285-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Precipitation is one of the main components in the water balance, and probably the component determined with the greatest uncertainties. In the present paper we focus on precipitation (mainly rain) over the Baltic Sea as a part of the BAL-TEX project to examine the present state of the art concerning different precipitation estimates over that area. Several methods are used, with the focus on 1) interpolation of available synoptic stations; 2) a mesoscale analysis system including synoptic, automatic, and climate stations, as well as weather radar and an atmospheric model; and 3) measurements performed on ships. The investigated time scales are monthly and yearly and also some long-term considerations are discussed. The comparison shows that the differences between most of the estimates, when averaged over an extended period and a larger area, are in the order of 10-20%, which is in the same range as the correction of the synoptic gauge measurements due to wind and evaporation losses. In all data sets using gauge data it is important to include corrections for high winds. To improve the structure of precipitation over sea more focus is to be put on the use of radar data and combinations of radar data and other data. Interpolation methods that do not consider orographic effects must treat areas with large horizontal precipitation gradients with care. Due to the large variability in precipitation in time and space, it is important to use long time periods for climate estimates of precipitation. Ship measurements are a valuable contribution to precipitation information over sea, especially for seasonal and annual time scales.

  • 335.
    Rutgersson, Anna
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Räisänen, Jouni
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Net precipitation over the Baltic Sea during present and future climate conditions2002Ingår i: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 22, nr 1, s. 27-39Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    By using a process-oriented ocean model forced with data from a gridded synoptic database, net precipitation values (precipitation minus evaporation) over the Baltic Sea are obtained. For a range of realistic meteorological forcing the average annual value obtained from an 18 yr (1981-1998) simulation ranges between 1100 and 2500 m(3) s(-1). The monthly variations are significant with the highest values occurring in early summer and even negative values in late autumn. Ice is an important factor, and the net precipitation is close to zero in the southern basins with no ice. Calculated net precipitation for a 98 yr period (1901-1998) using river runoff and maximum ice extent indicates that the investigated 18 yr period was wetter than the almost 100 yr climate mean. A realistic climate estimate of net precipitation during the 20th century is estimated to be 1500 +/-1000 m(3) s(-1). The evaluation of 2 present day regional climate simulations indicated high precipitation, low evaporation, and thus excessive net precipitation compared to the climate estimate from this investigation. When simulating the effect of increased greenhouse gases, the change in net precipitation was positive but small due to the compensating effects of increased precipitation and increased evaporation associated with increased temperature and reduced ice.

  • 336.
    Rutgersson, Anna
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Smedman, A S
    Omstedt, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Measured and simulated latent and sensible heat fluxes at two marine sites in the Baltic Sea2001Ingår i: Boundary-layer Meteorology, ISSN 0006-8314, E-ISSN 1573-1472, Vol. 99, nr 1, s. 53-84Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, turbulent heat flux data from two sites within the Baltic Sea are compared with estimates from two models. The main focus is on the latent heat flux. The measuring sites are located on small islands close to the islands of Bornholm and Gotland. Both sites have a wide wind direction sector with undisturbed over-water fetch. Mean parameters and direct fluxes were measured on masts during May to December 1998. The two models used in this study are the regional-scale atmospheric model HIRLAM and the ocean model PROBE-Baltic. It is shown that both models overestimate the sensible and latent heat fluxes. The overestimation can, to a large extent, be explained by errors in the air-water temperature and humidity differences. From comparing observed and modelled data, the estimated 8-month mean errors in temperature and humidity are up to 1 degreesC and 1 g kg(-1),respectively. The mean errors in the sensible and latent heat fluxes for the same period are approximately 15 and 30 W m(-2), respectively. Bulk transfer coefficients used for calculating heat and humidity fluxes at the surface were shown to agree rather well with the measurements, at least for the unstable data. For stable stratification, the scatter in data is generally large, and it appears that the bulk formulation chosen overestimates turbulent heat fluxes.

  • 337. Rydberg, Lars
    et al.
    Aertebjerg, Gunni
    Edler, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Fifty years of primary production measurements in the Baltic entrance region, trends and variability in relation to land-based input of nutrients2006Ingår i: Journal of Sea Research, ISSN 1385-1101, E-ISSN 1873-1414, Vol. 56, nr 1, s. 1-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inter-annual variations and long-term trends in phytoplankton primary production (PP) within the Baltic entrance region (the Kattegat and the Belt Sea) are presented and discussed. The study employs the core of Danish monitoring data, with measurements at 6-8 different sites from the past 20-50 years. Temporal development of the annual PP is compared with changes and variations in the land-based nutrient inputs and to other, independent, Swedish and Danish PP data. Spatial and seasonal variations based on annual and monthly PP, respectively, are evaluated. There are large variations on all scales; annual PP ranges from 50 to 500 g C m(-2), with maximum values in some Danish fjords and minimum values in open waters during the 1950s. The Kattegat and the Sound have a lower mean production (135-165 g C m(-2); 1981-2000) than the Great and Little Belts (185-220 g C m(-2)). Compared to 1950s and 1960s, the daily PP has changed from being almost constant between March and October, to having two more distinct maxima, one in March and one between July and September. It is obvious that annual mean production has increased considerably since the 1950s, but also that this increase took place before 1980. For data after 1980, we find a co-variation between annual nutrient loads and regional mean PP; years of low total nitrogen (TN) and total phosphorus (TP) input to the region coincide with low PP and vice versa. Waste-water treatment and measures in agriculture have reduced the land-based input of TN by about 1/3 and input of TP by about 2/3 since the 1980s, enough to cause a substantial decrease in the surface water nutrient concentrations. A simultaneous, but weak downward trend in the regional mean PP can be seen up to 1997, after which the trend is broken. Higher production from 1998 is most likely an effect of changes in the method used for determination of PP. (c) 2006 Elsevier B.V. All rights reserved.

  • 338.
    Räisänen, Jouni
    et al.
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hansson, U
    Ullerstig, Anders
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Doescher, Ralf
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Graham, Phil
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Jones, Colin
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Samuelsson, Patrick
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Willen, Ulrika
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    European climate in the late twenty-first century: regional simulations with two driving global models and two forcing scenarios2004Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 22, nr 1, s. 13-31Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A basic analysis is presented for a series of regional climate change simulations that were conducted by the Swedish Rossby Centre and contribute to the PRUDENCE (Prediction of Regional scenarios and Uncertainties for Defining EuropeaN Climate change risks and Effects) project. For each of the two driving global models HadAM3H and ECHAM4/OPYC3, a 30-year control run and two 30-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with the regional model. In this way, four realizations of climate change from 1961-1990 to 2071-2100 were obtained. The simulated changes are larger for the A2 than the B2 scenario (although with few qualitative differences) and in most cases in the ECHAM4/OPYC3-driven (RE) than in the HadAM3H-driven (RH) regional simulations. In all the scenario runs, the warming in northern Europe is largest in winter or late autumn. In central and southern Europe, the warming peaks in summer when it locally reaches 10 degreesC in the RE-A2 simulation and 6-7 degreesC in the RH-A2 and RE-B2 simulations. The four simulations agree on a general increase in precipitation in northern Europe especially in winter and on a general decrease in precipitation in southern and central Europe in summer, but the magnitude and the geographical patterns of the change differ markedly between RH and RE. This reflects very different changes in the atmospheric circulation during the winter half-year, which also lead to quite different simulated changes in windiness. All four simulations show a large increase in the lowest minimum temperatures in northern, central and eastern Europe, most likely due to reduced snow cover. Extreme daily precipitation increases even in most of those areas where the mean annual precipitation decreases.

  • 339.
    Sahlberg, Jörgen
    SMHI, Affärsverksamhet. SMHI, Forskningsavdelningen, Oceanografi.
    Physical modelling of the Akkajaure reservoir2003Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 7, nr 3, s. 268-282Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper describes the seasonal temperature development in the Akkajaure reservoir. one of the largest Swedish reservoirs. It lies in the headwaters of the river Lulealven in northern Sweden: it is 60 km long and 5 km wide with a maximum depth of 92 m. The maximum allowed variation in surface water level is 30 m. The temperature field in the reservoir is important for many biochemical processes. A one-dimensional lake model of the Akkajaure reservoir is developed from a lake model by Sahlberg (1983 and 1988). The dynamic eddy viscosity is calculated by a two equation turbulence model, a k-epsilon model and the hypolimnic eddy diffusivity formulation which is a function of the stability frequency (Hondzo et al., 1993). A comparison between calculated and measured temperature profiles showed a maximum discrepancy of 0.5-1.0degreesC over the period 1999-2002. Except for a few days in summer, the water temperature is vertically homogeneous. Over that period of years, a weak stratification of temperature occurred on only one to two weeks a year on different dates in July and August. This will have biological consequences.

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  • 340.
    Sahlberg, Jörgen
    et al.
    SMHI, Affärsverksamhet. SMHI, Forskningsavdelningen, Oceanografi.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    Light limitation of primary production in high latitude reservoirs2005Ingår i: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 9, nr 6, s. 707-720Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To explore the effects of vertical mixing on the primary production in a northern reservoir, a Lagrangian particle dispersion model was coupled to a 1-D reservoir model where the vertical mixing was calculated using a k-epsilon model together with an empirically-based deep-water eddy viscosity. The primary production of each phytoplankton cell is assumed to be a function of the ambient light and not to be nutrient limited. The photoadaption follows first-order kinetics where the photoadaptive variables, alpha, beta, and P(m), describe the coefficients of the photosynthesis-irradiance curve. The model is applied to the northern reservoir Akkajaure, which is strongly regulated with a mean and maximum depth of 30 m and 100 m respectively. Based on the release of 1000 particles (plankton), the model calculated the mean primary production of each plankton, during four different growing seasons. Vertical mixing has a substantial effect on the vertical distribution of phytoplankton and, thus, on the primary production in a reservoir. It was found that primary production was greater in a cold summer with weak stratification than in a warm summer when the reservoir was more stratified.

  • 341. Sanden, P
    et al.
    Håkansson, Bertil
    SMHI, Forskningsavdelningen, Oceanografi.
    Long-term trends in Secchi depth in the Baltic Sea1996Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 41, nr 2, s. 346-351Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Nutrient loads to the Baltic Sea have increased during the last century, and primary production has probably also risen. However, the evidence of such a rise is circumstantial, and most of the available findings concerning primary production cover only brief time periods. A more appropriate type of data in this area is Secchi disk measurements. We present the results of trend tests applied to Secchi depth values recorded during two discrete time periods: 1919-1939 and 1969-1991. We performed a step trend test to compare the data from the two periods and applied a monotonic trend test to the later series. Both tests showed that Secchi depth decreased by similar to 0.05 m yr(-1) during both periods. Calculations of changes in chlorophyll concentrations suggest a yearly increase of similar to 1%. Extending the calculations to represent primary production indicates an increase of slightly <1% yr(-1). These calculations, however, are unreliable due to substantial uncertainty regarding the relationships between Secchi depth and chlorophyll concentration and chlorophyll and primary production.

  • 342.
    Sandén, Per
    et al.
    SMHI, Forskningsavdelningen, Hydrologi.
    Rahm, Lars
    SMHI, Forskningsavdelningen, Oceanografi.
    WULFF, F
    NONPARAMETRIC TREND TEST OF BALTIC SEA DATA1991Ingår i: Environmetrics, ISSN 1180-4009, E-ISSN 1099-095X, Vol. 2, nr 3, s. 263-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The recently reported tendencies toward decreasing total amounts of silicate in the Baltic Sea are investigated by use of non-parametric trend analysis. The period 1968-1986 showed significant falling trends in surface waters from the whole system. The deepest parts of the Baltic proper did in contrast reveal strong increasing trends. These trends are more pronounced during the latter part of the analysis period which is characterized by stagnant conditions in the Baltic proper. These conditions have been prevailing since the major inflow in 1976. The causes of the observed changes are unclear. The increased load of nutrients and accompanying increase in primary production is, however, one factor. Another is coupled to the stagnation conditions of the Baltic Proper.

  • 343.
    Saraiva, Sofia
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Fernandes, L.
    van der Meer, J.
    Neves, R.
    Kooijman, S. A. L. M.
    The role of bivalves in the Balgzand: First steps on an integrated modelling approach2017Ingår i: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 359, s. 34-48Artikel i tidskrift (Refereegranskat)
  • 344.
    Saraiva, Sofia
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Baltic Sea ecosystem response to various nutrient load scenarios in present and future climates2019Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 52, nr 5-6, s. 3369-3387Artikel i tidskrift (Refereegranskat)
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    fulltext
  • 345.
    Saraiva, Sofia
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Andersson, Helén
    SMHI, Forskningsavdelningen, Oceanografi.
    Höglund, Anders
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Groger, Matthias
    SMHI, Forskningsavdelningen, Oceanografi.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    Eilola, Kari
    SMHI, Forskningsavdelningen, Oceanografi.
    Uncertainties in Projections of the Baltic Sea Ecosystem Driven by an Ensemble of Global Climate Models2019Ingår i: FRONTIERS IN EARTH SCIENCE, ISSN 2296-6463, Vol. 6, artikel-id UNSP 244Artikel i tidskrift (Refereegranskat)
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    fulltext
  • 346.
    Schimanke, Semjon
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Dieterich, Christian
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    An algorithm based on sea-level pressure fluctuations to identify major Baltic inflow events2014Ingår i: Tellus. Series A, Dynamic meteorology and oceanography, ISSN 0280-6495, E-ISSN 1600-0870, Vol. 66, artikel-id 23452Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Major Baltic inflows are an important process to sustain the sensitive steady state of the Baltic Sea. We introduce an algorithm to identify atmospheric variability favourable for major Baltic inflows. The algorithm is based on sea-level pressure (SLP) fields as the only parameter. Characteristic SLP pattern fluctuations include a precursory phase of 30 days and 10 days of inflow period. The algorithm identifies successfully the majority of observed major Baltic inflows between 1961 and 2010. In addition, the algorithm finds some occurrences which cannot be related to observed inflows. In these cases with favourable atmospheric conditions, inflows were precluded by contemporaneously existing saline water masses or strong freshwater supply. Moreover, the algorithm clearly identifies the stagnation periods as a lack of SLP variability favourable for MBIs. This indicates that the lack of inflows is mainly a consequence of missing atmospheric forcing during this period. The only striking inflow which is not identified by the algorithm is the event in January 2003. We demonstrate that this is due to the special evolution of SLP fields which are not comparable with any other event. Finally, the algorithm is applied to an ensemble of scenario simulations. The result indicates that the number of atmospheric events favourable for major Baltic inflows increases slightly in all scenarios.

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  • 347.
    Schimanke, Semjon
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    A regional climate model simulation over the Baltic Sea region for the last Millennium2011Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Variabilitet och långsiktig klimatförändring i Fennoskandien undersöks i en 1000 år lång under det senaste milleniet i en 1000 år lång klimatmodellsimulering. Vi använder Rossby Centres regionala klimatmodell (RCA3) med randvärden från en global klimatmodell (GCM). Effekten av variabilitet i solinstrålning, ändrade astronomiska förhållanden och ändringar i växthusgskoncentrationer har använts för att driva modellerna. Resultaten visar att RCA3 genererar en medeltida varm period (MCA) som är den varmaste under hela milleniet undantaget 1900-talet. Dessutom visar resultaten på en kall ”Lilla Istid” (LIA). I simuleringen motsvarar dessa perioder 1100- 1299 (MCA) samt 1600-1799 (LIA). Det här överensstämmer med rekonstruktioner och kan till största delen relateras till ändringar i solinstrålning. Vi fann vidare att variabiliteten över flera decennier har en betydande effekt på klimatet under MCA och LIA. Variabiliteten över flera decennier kan ibland också förklara motsägelsefulla rekonstruktioner om dessa är representativa för kortare icke sammanfallande perioder. I tillägg till tidsserier, undersöker vi också rumsliga mönster hos temperatur, lufttryck i havsytans nivå, nederbörd, molntäcke, vindhastighet och byighet för både säsongs- och årsmedelvärden. De flesta parametrarna visar störst skillnad mellan olika perioder för vintersäsongen. Som exempel kan nämnas att vintern under MCA var 1-2.5 K varmare än under LIA sett som medelvärde över flera decennier. Variabilitet och långsiktig klimatförändring i Fennoskandien undersöks i en 1000 år lång under det senaste milleniet i en 1000 år lång klimatmodellsimulering. Vi använder Rossby Centres regionala klimatmodell (RCA3) med randvärden från en global klimatmodell (GCM). Effekten av variabilitet i solinstrålning, ändrade astronomiska förhållanden och ändringar i växthusgskoncentrationer har använts för att driva modellerna. Resultaten visar att RCA3 genererar en medeltida varm period (MCA) som är den varmaste under hela milleniet undantaget 1900-talet. Dessutom visar resultaten på en kall ”Lilla Istid” (LIA). I simuleringen motsvarar dessa perioder 1100- 1299 (MCA) samt 1600-1799 (LIA). Det här överensstämmer med rekonstruktioner och kan till största delen relateras till ändringar i solinstrålning. Vi fann vidare att variabiliteten över flera decennier har en betydande effekt på klimatet under MCA och LIA. Variabiliteten över flera decennier kan ibland också förklara motsägelsefulla rekonstruktioner om dessa är representativa för kortare icke sammanfallande perioder. I tillägg till tidsserier, undersöker vi också rumsliga mönster hos temperatur, lufttryck i havsytans nivå, nederbörd, molntäcke, vindhastighet och byighet för både säsongs- och årsmedelvärden. De flesta parametrarna visar störst skillnad mellan olika perioder för vintersäsongen. Som exempel kan nämnas att vintern under MCA var 1-2.5 K varmare än under LIA sett som medelvärde över flera decennier. Variabilitet och långsiktig klimatförändring i Fennoskandien undersöks i en 1000 år lång under det senaste milleniet i en 1000 år lång klimatmodellsimulering. Vi använder Rossby Centres regionala klimatmodell (RCA3) med randvärden från en global klimatmodell (GCM). Effekten av variabilitet i solinstrålning, ändrade astronomiska förhållanden och ändringar i växthusgskoncentrationer har använts för att driva modellerna. Resultaten visar att RCA3 genererar en medeltida varm period (MCA) som är den varmaste under hela milleniet undantaget 1900-talet. Dessutom visar resultaten på en kall ”Lilla Istid” (LIA). I simuleringen motsvarar dessa perioder 1100- 1299 (MCA) samt 1600-1799 (LIA). Det här överensstämmer med rekonstruktioner och kan till största delen relateras till ändringar i solinstrålning. Vi fann vidare att variabiliteten över flera decennier har en betydande effekt på klimatet under MCA och LIA. Variabiliteten över flera decennier kan ibland också förklara motsägelsefulla rekonstruktioner om dessa är representativa för kortare icke sammanfallande perioder. I tillägg till tidsserier, undersöker vi också rumsliga mönster hos temperatur, lufttryck i havsytans nivå, nederbörd, molntäcke, vindhastighet och byighet för både säsongs- och årsmedelvärden. De flesta parametrarna visar störst skillnad mellan olika perioder för vintersäsongen. Som exempel kan nämnas att vintern under MCA var 1-2.5 K varmare än under LIA sett som medelvärde över flera decennier. Variabilitet och långsiktig klimatförändring i Fennoskandien undersöks i en 1000 år lång under det senaste milleniet i en 1000 år lång klimatmodellsimulering. Vi använder Rossby Centres regionala klimatmodell (RCA3) med randvärden från en global klimatmodell (GCM). Effekten av variabilitet i solinstrålning, ändrade astronomiska förhållanden och ändringar i växthusgskoncentrationer har använts för att driva modellerna. Resultaten visar att RCA3 genererar en medeltida varm period (MCA) som är den varmaste under hela milleniet undantaget 1900-talet. Dessutom visar resultaten på en kall ”Lilla Istid” (LIA). I simuleringen motsvarar dessa perioder 1100- 1299 (MCA) samt 1600-1799 (LIA). Det här överensstämmer med rekonstruktioner och kan till största delen relateras till ändringar i solinstrålning. Vi fann vidare att variabiliteten över flera decennier har en betydande effekt på klimatet under MCA och LIA. Variabiliteten över flera decennier kan ibland också förklara motsägelsefulla rekonstruktioner om dessa är representativa för kortare icke sammanfallande perioder. I tillägg till tidsserier, undersöker vi också rumsliga mönster hos temperatur, lufttryck i havsytans nivå, nederbörd, molntäcke, vindhastighet och byighet för både säsongs- och årsmedelvärden. De flesta parametrarna visar störst skillnad mellan olika perioder för vintersäsongen. Som exempel kan nämnas att vintern under MCA var 1-2.5 K varmare än under LIA sett som medelvärde över flera decennier.

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  • 348.
    Schimanke, Semjon
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Decadal-to-Centennial Variability of Salinity in the Baltic Sea2016Ingår i: Journal of Climate, ISSN 0894-8755, E-ISSN 1520-0442, Vol. 29, nr 20, s. 7173-7188Artikel i tidskrift (Refereegranskat)
  • 349.
    Schimanke, Semjon
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Meier, Markus
    SMHI, Forskningsavdelningen, Oceanografi.
    Kjellström, Erik
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Strandberg, Gustav
    SMHI, Forskningsavdelningen, Klimatforskning - Rossby Centre.
    Hordoir, Robinson
    SMHI, Forskningsavdelningen, Oceanografi.
    The climate in the Baltic Sea region during the last millennium simulated with a regional climate model2012Ingår i: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 8, nr 5, s. 1419-1433Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Variability and long-term climate change in the Baltic Sea region is investigated for the pre-industrial period of the last millennium. For the first time dynamical down-scaling covering the complete millennium is conducted with a regional climate model in this area. As a result of changing external forcing conditions, the model simulation shows warm conditions in the first centuries followed by a gradual cooling until ca. 1700 before temperature increases in the last centuries. This long-term evolution, with a Medieval Climate Anomaly (MCA) and a Little Ice Age (LIA), is in broad agreement with proxy-based reconstructions. However, the timing of warm and cold events is not captured at all times. We show that the regional response to the global climate anomalies is to a strong degree modified by the large-scale circulation in the model. In particular, we find that a positive phase of the North Atlantic Oscillation (NAO) simulated during MCA contributes to enhancing winter temperatures and precipitation in the region while a negative NAO index in the LIA reduces them. In a second step, the regional ocean model (RCO-SCOBI) is used to investigate the impact of atmospheric changes onto the Baltic Sea for two 100 yr time slices representing the MCA and the LIA. Besides the warming of the Baltic Sea, the water becomes fresher at all levels during the MCA. This is induced by increased runoff and stronger westerly winds. Moreover, the oxygen concentrations in the deep layers are slightly reduced during the MCA. Additional sensitivity studies are conducted to investigate the impact of even higher temperatures and increased nutrient loads. The presented experiments suggest that changing nutrient loads may be more important determining oxygen depletion than changes in temperature or dynamic feedbacks.

  • 350.
    Schimanke, Semjon
    et al.
    SMHI, Forskningsavdelningen, Oceanografi.
    Spangehl, T.
    Huebener, H.
    Cubasch, U.
    Variability and trends of major stratospheric warmings in simulations under constant and increasing GHG concentrations2013Ingår i: Climate Dynamics, ISSN 0930-7575, E-ISSN 1432-0894, Vol. 40, nr 7-8, s. 1733-1747Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ensemble simulations with a coupled ocean-troposphere-stratosphere model for the pre-industrial era (1860 AD), late twentieth century (1990 AD) greenhouse gas (GHG) concentrations, the SRES scenarios B1, A1B, A2, as well as stabilization experiments up to the Twenty-third century with B1 and A1B scenario GHG concentrations at their values at 2100, have been analyzed with regard to the occurrence of major sudden stratospheric warmings (SSWs). An automated algorithm using 60A degrees N and 10 hPa zonal wind and the temperature gradient between 60A degrees N and the North Pole is used to identify this phenomenon in the large data set. With 1990 CO2 concentrations (352 ppmv), the frequency of simulated SSWs in February and March is comparable to observation, but they are underestimated during November to January. All simulations show an increase in the number of SSWs from the pre-industrial period to the end of the twenty-first century, indicating that the increase of GHG is also reflected in the number of sudden warmings. However, a high variability partially masks the underlying trend. Multi-century averages during the stabilization periods indicate that the increase of SSWs is linear to the applied radiative forcing. A doubling of SSWs occurs when the GHG concentration reaches the level of the A2 scenario at the end of the twenty-first century (836 ppmv). The increase in SSWs in the projections is caused by a combination of increased wave flux from the troposphere and weaker middle atmospheric zonal winds.

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