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Influence of planetary waves on the biogeochemical system in the global ocean

Final Activity Report Summary - BioWaves (Influence of planetary waves on the biogeochemical system in the global ocean)

The BIOWAVES project aimed to quantitatively assess the influence of planetary waves on the biogeochemical system in the global ocean, by using a realistically coupled physical and biogeochemical model. Planetary waves represent a key process to maintain the ocean circulation and propagate potential energy in oceans. These waves have a distinct signature in chlorophyll concentrations, suggesting a potential impact of these waves on marine ecosystems.

To investigate these coupled physical and biogeochemical basin-scale interactions, the present study was based on a general circulation model coupled with a simple biogeochemical model that was divided in five compartments, namely dissolved inorganic nitrogen, phytoplankton, zooplankton, detritus and dissolved organic nitrogen. Two configurations, based on two physical models, i.e. OPA8 and its improved version NEMO, were implemented.

The first one was applied for case studies over twenty zonal transects in the north Atlantic. This approach showed that planetary waves were able to generate both positive and negative local variations in primary production, suggesting a net weak effect at basin scale, as described in the publication by Charria et al., in ‘Ocean Science’ in 2008.

With the second configuration a basin-scale experiment was setup over the entire north Atlantic to investigate the influence of the waves on primary and exported production. The biogeochemical model was run using physical fields in which the westward propagating features were filtered out. This experiment showed a general decrease of the primary production over the basin, with larger decrease north of 40° N. This study was the first basin-scale estimation of the influence of westward propagating features on the biological productions. Its results contributed to the estimation of the impacts of physical oceanic processes on biological activity and, by extension, on the marine biological pump. Therefore this study contributed towards a better knowledge of one of the most pressing problems in contemporary science, i.e. the quantification of the carbon cycle.