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The impact of (sub-)mesoscale eddies on the soft-tissue carbon pump. Anne Willem Omta Bas Kooijman Theoretical Life Sciences, Vrije Universiteit (Amsterdam) Henk Dijkstra IMAU, Universiteit Utrecht www.bio.vu.nl/thb. Grant No. 635.100.009 (Computational Life Sciences).
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The impact of (sub-)mesoscale eddies on the soft-tissue carbon pump Anne Willem Omta Bas Kooijman Theoretical Life Sciences, Vrije Universiteit (Amsterdam) Henk Dijkstra IMAU, Universiteit Utrecht www.bio.vu.nl/thb Grant No. 635.100.009 (Computational Life Sciences)
Ocean eddy field Real ocean eddy field very complicated: simulate one single eddy for better understanding
Flow model • Non-hydrostatic 3-D model • Domain 32 km * 32 km * 1 km • Periodic boundary conditions
Phytoplankton Internal Nitrogen and Carbon (PINC) model • PINC organisms consist of: • biomass structure (91% C, 9% N) • carbon reserve (100% C) • nitrogen reserve (100% N) • Ratio of components determines C:N ratio of organisms
Initial conditions • Biomass: • C:N ratio of 11:1 • Sinking of organic carbon and nitrogen balanced by upward diffusion of DIC and DIN • Eddy radius ~8 km, no vertical velocity
Vertical velocity patterns 7.2 days 3.6 days 12 days
Plankton distributions 7.2 days 12 days Upwelling of DIN leads to strong biomass increase, first in lobes, later also in centre of eddy
Net effect on DIC/DIN after 12 days DIN and DIC increase, because not all the upwelled DIN and DIC are consumed DIC increase DIN increase DIC decrease DIN decrease
R decreases in time, because organisms receive more N C:N ratio (R)
Conclusion The submesoscale eddy weakens the soft-tissue carbon pump, because: • Not all the upwelling DIN is consumed - could also be shown with fixed-stoichiometry plankton model • The C:N ratio of phytoplankton decreases - could only shown with flexible-stoichiometry plankton model More information: www.bio.vu.nl/thb