Abstract
We assess the performance of an eddy-recognizing numerical ocean model in simulating the pattern and variability of the hydrography in the Skagerrak/northern North Sea area. The model we use is a version of the widely used Princeton ocean model employing a terrain-following vertical coordinate. Results from a series of five multi-year simulations of the mesoscale response are described. The simulations differ in their representation of the lateral freshwater supply to the model ocean of which the first is a reference simulation. The next four are variations in which the river discharges and/or the Baltic outflow are given more realistic representations. For validation, we have used in situ hydrographic data. A novelty is that we use the concepts of freshwater height and potential energy anomaly as objective validation tools. We find that, in general, the model faithfully reproduces many of the observed hydrographic features including their mean patterns and their variance. Not surprisingly, we find that the Baltic outflow is by far the most significant freshwater source in terms of its influence on the hydrography in the area, a result corroborating earlier findings. The best validation is obtained when all freshwater supply is made as realistic as possible, in particular the Baltic outflow. We also find that the large scale cyclonic circulation and the location of fronts are robust characteristics of the Skagerrak/northern North Sea circulation given the impact changes in the freshwater input has on the hydrography. Finally, we find that a further exploration of the impact of the lateral open boundary forcing, e.g., the input of Atlantic water, is needed.
Similar content being viewed by others
References
Albretsen J (2007) The impact of freshwater discharges on the ocean circulation in the Skagerrak/northern North Sea area. Part II: Energy analysis, (this volume)
Albretsen J, Røed LP (2006) Sensitivity of Skagerrak dynamics to freshwater discharges: insight from a numerical model. In: Dahlin H, Flemming NC, Marchand P, Petersson SE (eds) Operational oceanography: present and future. Proceedings of the 4th International Conference on EuroGOOS, 6–9 June 2005, Brest, France, pp 773–779, EuroGOOS Office, SMHI, and European Commission Research Directorate
Bergstrøm S, Carlsson B (1994) River runoff to the Baltic Sea: 1950–1990. Ambio 23:280–287
Berntsen J, Svendsen E (1999) Using the SKAGEX dataset for evaluation of ocean model skills. J Mar Syst 18:313–331
Berntsen J, Svendsen E, Ostrowski M (1966) Validation and sensitivity study of a sigma-coordinate ocean model using the Skagex dataset. ICES CM 1996/C:5
Björk G, Gustafsson B, Stigebrandt S (2001) Upper layer circulation of the Nordic Seas as inferred from the spatial distribution of heat and freshwater content and potential energy. Polar Res 20:161–168
Blumberg AF, Mellor GL (1987) A description of a three-dimensional coastal ocean circulation model. In: Heaps N (ed) Three-dimensional coastal ocean models, vol 4. Coastal and Estuarine Sciences, American Geophys, Union
Curry R, Mauritzen C (2005) Dilution of the northern North Atlantic Ocean in recent decades. Science 308:1772–1774
Curry R, McCartney MS (2001) Ocean gyre circulation changes associated with the North Atlantic Oscillation. J Phys Oceanogr 31:3374–3400
Danielsen DS, Davidson L, Edler L, Fogelqvist E, Fonselius S, Føyn L, Hernroth L, Håkansson B, Olsson I, Svendsen E (1991) SKAGEX: some preliminary results. In: ICES Statuary Meeting, C.M./C:2
Danielsen DS, Edler L, Fonselius S, Hernroth L, Ostrowski M, Svendsen E (1997) Oceanographic variability in Skagerrak/northern Kattegat, May–June 1990. ICES J Mar Sci 55:753–773
Engedahl H (1995) Implementation of the Princeton ocean model (POM/ECOM-3D) at the Norwegian Meteorological Institute (DNMI). Research Report 5, Norwegian Meteorological Institute
Engedahl H, Ådlandsvik B, Martinsen EA (1998) Production of monthly mean climatological archives for the Nordic Seas. J Mar Sys 14:1–26
Flather RA (1981) Results from a model of the north-east Atlantic relating to the Norwegian coastal current. In: Sætre R, Mork M (eds) Norwegian coastal current symposium vol II. University of Bergen, p 31
Fofonoff NP (1962) Dynamics of ocean currents. In: Hill NM (ed) The Sea: ideas and observations on progress in the study of the sea, vol 1. Wiley, pp 323–395
Fossum I (2006) Analysis of instabilities and mesoscale motion off southern Norway. J Geophys Res 111. doi:10.1029/2005JC003228
Gjevik B, Nøst E, Straume T (1990) Atlas of tides on the Shelves of the Norwegian and Barents Seas. Tech. Rep. F&U-ST 90012 Statoil, Department of Mathematics, University of Oslo
Gustafsson B (1997) Interaction between Baltic Sea and North Sea. D. Hydrogr Zeit 49:163–181
Gustafsson B (1999) High frequency variability of the surface layers in the Skagerrak during SKAGEX. Cont Shelf Res 19:1021–1047
Gustafsson B, Andersson HC (2001) Modeling the exchange of the Baltic Sea from the meridional atmospheric pressure difference across the North Sea. J Geophys Res 106:19, 731–19,744
Gustafsson B, Stigebrandt A (1996) Dynamics of the freshwater-influenced surface layers in the Skagerrak. J Sea Res 35:39–53
Ikeda M, Johannessen J, Lygre K, Sandven S (1989) A process study of mesoscale meanders and eddies in the Norwegian Coastal Current: J Phys Oceanogr 19:20–35
James I (1991) A primitive equation model simulation of eddies in the Norwegian Coastal Current. J Phys Oceanogr 21:893–902
Johannessen J, Svendsen E, Sandven S, Johannessen OM, Lygre K (1989) 3-dimensional structure of mesoscale eddies in the Norwegian Coastal Current. J Phys Oceanogr 19:3–19
Johannessen OM, Mork M (1979) Remote sensing experiments in the Norwegian coastal waters. Tech. Rep. Report No. 3/9, Geophysical Institute, University of Bergen, Norway
LaCasce J, Engedahl H (2005) Statistics of low frequency currents over the western Norwegian shelf and slope II: Model. Ocean Dyn 55:222–237. doi:10.1007/s10,236–005–0022–5
Langenberg H (1998) Features of coastal current instabilities in the North Sea: results of a numerical model. J Geophys Res 103:7681–7691
Martinsen EA, Engedahl H, Ottersen G, Ådlandsvik B, Loeng H, Balino B (1992) Metocean modeling project: climatological and hydrographical data for hindcast of ocean currents, Tech. Rep. 100 Norwegian Meteorological Institute
Mattson J (1996) Some comments on the barotropic flow through the Danish straits and the division of the flow between the belt sea and Øresund. Tellus 48:456–464
Melsom A (2005) Mesoscale activity in the North Sea as seen in ensemble simulations. Ocean Dyn 55:338–350
Omstedt A, Meuller L, Nyberg L (1997) Interannual, seasonal and regional variations of precipitation and evaporation over the Baltic Sea. Ambio 26:484–492
Rodhe J (1987) The large-scale circulation in the Skagerrak, interpretation of some observations. Tellus 39A:245–253
Rodhe J (1996) On the dynamics of the large-scale circulation of the Skagerrak. J Sea Res 35:9–21
Rodhe J, Tett P, Wulff F (2006) The Baltic and North Seas: a regional review of some important physical–chemical–biological interaction processes. In: Robinson AR, Brink K (eds) The sea, vol 14. Harvard Univ. Press
Røed LP, Debernard J (2004) Description of an integrated flux and sea-ice model suitable for coupling to an ocean and atmosphere model, met.no Report 4/2004, Norwegian Meteorological Institute
Røed LP, Fossum I (2004) Mean and eddy motion in the Skagerrak/northern North Sea: insight from a numerical model. Ocean Dyn 54:197–220
Sætre R, Mork M (eds) (1981) The Norwegian Coastal Current. In: Proceedings from the norwegian coastal current symposium, Geilo 9–12 September 1980, University of Bergen, Norway
Skogen M, Moll A (2005) Importance of ocean circulation in ecological modeling: an example from the North Sea. J Mar Syst 57:289–300
Skogen MD, Svendsen E, Søiland H (2002) Environmental status of the Skagerrak and North Sea 2000, Tech. rep., Institute of Marine Research, Bergen, Norway. Available at http://www.imr.no/~morten/nocomments
Skogen MD, Svendsen E, Søiland H (2003) Environmental status of the Skagerrak and North Sea 2001, Tech. rep., Institute of Marine Research, Bergen, Norway. Available at http://www.imr.no/~morten/nocomments
Stigebrandt A (1980) Barotropic and baroclinic response of a semi-enclosed basin to barotropic forcing of the sea. In: Freeland DF, Levings HJ, Levings C (eds) Proceedings of the NATO conference of fjord oceanography, pp 141–164
Stigebrandt A (1983) A model for the exchange of water and salt between the Baltic and the Skagerrak. J Phys Oceanogr 13:411–427
Stigebrandt A (1984) Analysis of a 89-year long sea level record from the Kattegat with special reference to the barotropically driven water exchange between the Baltic and the sea. Tellus Ser A 36:411–427
Author information
Authors and Affiliations
Corresponding author
Additional information
Responsible editor: Phil Dyke
Rights and permissions
About this article
Cite this article
Røed, L.P., Albretsen, J. The impact of freshwater discharges on the ocean circulation in the Skagerrak/northern North Sea area Part I: model validation. Ocean Dynamics 57, 269–285 (2007). https://doi.org/10.1007/s10236-007-0122-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10236-007-0122-5