Finnish Environment Institute | Suomen ympäristökeskus | Finlands miljöcentral

sykefi header valkoinen

Development of a 3D hydrodynamic and ecological model for Finnish waters

+ Show information

Basic project information


  • To study the applicability of the COHERENS-model to Finnish waters.
  • To develop the ecological part of the model to better describe the ecology of Finnish coastal and inland waters.

COHERENS is the new research model of SYKE for hydrodynamic modelling. It has originally been developed by the Management Unit for the Management of Mathematical Models for the North Sea (MUMM, Luyten et al. 1999) in Belgium.

•       The model consists of a physical model with sub modules for currents, salinity and simple temperature.
•       A biological model which simulates the biological processes.
•       A sediment model which describes the sinking of suspended inorganic and organic substances.
•       Modules for the description of the spreading of harmful substances which can be resolved either as a concentration at a point or the spreading of tracers with a neutral buoyancy.

The COHERENS-model can be applied in either rectangular or spherical coordinates depending on the size of the water body. Runs can be made in either 1 or 3 dimension. The model utilizes sigma-coordinates in the vertical making the modeling of bottom-flow possible.

The physical part of the model was a part of the EMAPS intercomparison project which studied the suitability of 6 different models for eutrophication calculations in Baltic. The COHERENS-model was found to perform reasonably well when using the same forcing as the other models.

The biological model of COHERENS was originally not suitable for Finnish waters because it is relatively simple with phosphorous missing from the state variables and only one algal group. One of the aims of this study is to take the ecology and sediment sub models from the YVA-SYKE model and implement them in COHERENS. They have been found to work well in the Gulf of Finland (Kiirikki et al. 2006).


Kiirikki, M., Lehtoranta, J., Inkala, A., Pitkänen, H., Hietanen, S., Hall, P.O.J., Tengberg, A., Koponen, J. and Sarkkula, J. 2006. A simple sediment process description suitable for 3D-ecosystem modelling - Development and testing in the Gulf of Finland. Journal of Marine Systems 61: 55–66.

Luyten, P. J., Jones, J. E., Proctor, R., Tabor, A., Tett, P., Wild-Allen, K., 1999. COHERENS - A coupled hydrodynamical-ecological model for regional and shelf seas: user documentation. MUMM report. Management Unit of the Mathematical Models of the North Sea, 911 pp.

Published 2013-04-25 at 12:53, updated 2013-04-25 at 12:51