Adjoint sensitivity of the air-sea CO₂ flux to ecosystem parameterization in a three-dimensional global ocean carbon cycle model

J. F. Tjiputra (1) , A. M. E. Winguth (1)

1 Department of Atmospheric Oceanic and Space Sciences [Madison]

The regional sensitivity of air-sea CO₂ flux to ecosystem components and parameters in a three-dimensional ocean carbon cycle model is estimated using an adjoint model. Adjoint sensitivities to the global air-sea CO₂ flux reveal that the biological component of the model is significant in the high latitudes of both hemispheres and in the Equatorial Pacific. More detailed analysis indicates that zooplankton grazing activity plays a major role in the carbon exchange in the above regions. The herbivores' ingestion parameter in the model regulates the flux of remineralized (i.e. regenerated) biogenic nutrients; thus, substantially controls the biological production and the concentration of dissolved inorganic carbon (DIC) in the euphotic zone. Over a 10-year period, reducing the herbivores' ingestion parameter in the model by 25% could increase the global uptake of atmospheric carbon by 6 Pg C. Thus, climate induced changes in the marine ecosystem structure are of importance for the future uptake of atmospheric CO₂.

Domains: Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]; Astrophysics [astro-ph]; Continental interfaces, environment; Ocean, Atmosphere; Earth Sciences

J. F. Tjiputra, A. M. E. Winguth. Adjoint sensitivity of the air-sea CO₂ flux to ecosystem parameterization in a three-dimensional global ocean carbon cycle model. Biogeosciences Discussions, 2007, 4 (2), pp.1377-1404. ⟨hal-00297890⟩