Geophysical Institute

Models nutrients in the ocean

Algae do not live long, and the nutrient content of the water can change quickly. If you want to predict the primary production in the Barents Sea one or ten years ahead, it is more important to know the current conditions of temperature ocean currents, than the nutrient content in the ocean here and now.

Filippa Fransner
Filippa Fransner
Filippa Fransner
Ocean water is always on the move, and both the water at a specific location today and the water that is transported there can influence future conditions. Whether the one or the other is most important, depends on the timescale.
Emil Jeansson

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This is Filippa Fransner's preliminary conclusion after having studied this in the Norwegian Earth System Model, NorESM. As a postdoc at the Bjerknes Centre for Climate Research and the Geophysical Institute at the University of Bergen, she studies the relationship between physics, chemistry and biology in the ocean. 

Physics in this case refers to ocean currents and temperature, while chemistry and biology includes nutrients, primary production and the exchange of CO2between the atmosphere and the ocean. Life in the ocean is influenced both by temperatures and currents, and by the access to nutrients. 

The last months, Filippa Fransner has looked into whether the biological and chemical conditions in the Barents Sea at one time influences the conditions for example ten years later.

At the annual meeting of the Norwegian national research project The Nansen Legacy, she will present results indicating that the amount of nutrients and primary production in the Barents Sea today will have little influence on the conditions in ten years. In The Nansen Legacy, 140 scientists from ten Norwegian research institutions cooperate on research on the climate and eco systems in the Barents Sea. This week they will meet in Bergen. 

Physical conditions are most important in the long run

If you want to predict the primary production next month or season, you have to know the nutrient content of the water now. On longer timescales, such as years and decades, the temperature of the water flowing northward is more important. Variations in the current cause variations in nutrients – according to the model. 

"It seems logical", says Filippa Fransner when asked whether this is also the case in the real world. 

The tiny organisms in the ocean do not live that long, and when they die, they sink. The access to nutrients changes as the water moves. The ocean, in itself, reacts much more slowly. As a result, ocean temperatures today can be seen to indicate the temperature years ahead. 

"To be certain, we have to compare the model results with observations from the ocean", Filippa Fransner emphasizes.

Aims to predict biological production

In the Norwegian model used to project the climate on really long time scales - the coming century – chemical and biological processes have already been implemented. But, in the model that will give more detailed predictions for the coming couple of decades, this is still lacking. Filippa Fransner will now work on implementing such a module. 

The aim is to be able to use the model to predict for instance primary production in the Barents Sea as far ahead as a decade.

This is also publised at the web-pages of  The Bjerknes Centre for climate research.

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