Sensitivity of sea-to-air CO2 flux to ecosystem parameters from an adjoint model
Other literature type
Tjiputra, J. F.
Winguth, A. M. E.
(issn: 1726-4189, eissn: 1726-4189)
An adjoint model is applied to examine the biophysical
factors that control surface pCO<sub>2</sub> in different ocean regions. In the
tropical Atlantic and Indian Oceans, the annual cycle of pCO<sub>2</sub> in the
model is highly dominated by temperature variability, whereas both the
temperature and dissolved inorganic carbon (DIC) are important in the
tropical Pacific. In the high-latitude North Atlantic and Southern Oceans,
DIC variability mainly drives the annual cycle of surface pCO<sub>2</sub>.
Phosphate addition significantly increases the carbon uptake in the tropical
and subtropical regions, whereas nitrate addition increases the carbon
uptake in the subarctic Pacific Ocean. The carbon uptake is also sensitive
to changes in the physiological rate parameters in the ecosystem model in
the equatorial Pacific, North Pacific, North Atlantic, and the Southern
Ocean. Zooplankton grazing plays a major role in carbon exchange, especially
in the HNLC regions. The grazing parameter regulates the phytoplankton
biomass at the surface, thus controlling the biological production and the
carbon uptake by photosynthesis. In the oligotrophic subtropical regions,
the sea-to-air CO<sub>2</sub> flux is sensitive to changes in the phytoplankton
exudation rate by altering the flux of regenerated nutrients essential for