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Modelling - a useful tool

Models are simplifications of the governing processes in nature and are used to study the state or the properties of nature that are difficult or impossible to measure directly. There are many different types of models, but the models most commonly applied at the Institute of Marine Research are so-called simulation models or numerical models. A numerical model describes processes by using equations which are solved numerically on large computers.

The applicability of models is large and ranges from pure descriptions of ocean currents and temperature to models that simulate the spreading of infections from aquaculture and models describing the interactions between the marine environment, plankton and fish.

In addition to describing the state, models also enable us to study the effects of various management strategies, pollution and climate change on fish stocks or other components of the ecosystem. Models are often the only viable tool when trying to assess and quantify various processes. Models are widely used in the assessment performed at the Institute of Marine Research.

The Institute of Marine Research utilizes many different models for a better understanding and quantification of the processes in the ocean. Generally, we can divide the models into five categories:

  • Circulation models. These models usually form the basis of our modelling activity. A circulation model resemble the models used in weather forecasting, and are used for calculating physical parameters such as currents, salinity, temperature, sea level and sea ice.
  • Dispersion models. The ocean is the conveyor belt for substances such as pollution, oil, fish larvae and salmon lice. A dispersion model utilizes the output from a circulation model to calculate how substances or small organisms are dispersed outward from a given source. This includes both where the dispersed matter ends up and how fast it is spreading.
  • Ecosystem models are used for describing parts of the ecosystem and their interactions. Such models can include one or more types of nutrients, plankton, fish and sea mammals. Similar to the dispersion models, the ecosystem models utilizes output from circulations models for the description of the physical environment. Additionally, ecosystem models often include a dispersion model.
  • Climate models. Circulation models for both ocean and atmosphere are used to project future climate. Climate models couples the ocean and atmosphere models together with modules for ice and snow (both terrestrial and oceanic), as well as vegetation on land and the carbon cycle.
  • Stock assessment models.



Models are by definition simplified representations of nature. Still they can give us valuable information about the physical, biological and population dynamic processes in the ocean. And in combination models can help us to gain insight and quantify the dynamics of the complex ecosystems.