Simulation of annual cycles of phytoplankton, zooplankton and nutrients using a mixed layer model coupled with a biological model

In oceanography, the mixed layer refers to the near surface part of the water column where physical and biological variables are distributed quasi homogeneously. Its depth depends on conditions at the air-sea interface (heat and freshwater fluxes, wind stress) and on the characteristics of the flow (stratification, shear), and has a strong influence on biological dynamics. The aim of this work is to model the behaviour of the mixed layer in waters situated to the south of Gran Canaria island, as well as the annual biological cycles (nutrients, planktons, detritus) which depend on it. To this end the one dimensional version of the ROMS (Regional Ocean Modelling System ) model is applied. The model consists of a physical model coupled with a biological one, with a mixed layer sub-model (K-Profile Parameterization). Initialization is done using mean profiles established from in situ data, forcing is from monthly means of heat fluxes, surface temperature, wind stress and heat flux sensitivity to sea surface temperature. These physical parameters are extracted from climatic databases and averaged over a 10-year period. Their annual variations are interpreted in order to physically predict the resulting behaviour of the mixed layer. The model is tested by means of a sensitivity analysis with respect to the forcing conditions, as well as through a comparison with other models for the case of idealized situations. Simulations are then performed, underlining, in summer, a strong stratification and a shallow mixed layer under the effect of the important heat fluxes; in late winter, a deep mixed layer due to convective mixing, causing an injection of nutrients into the layer and a phytoplankton bloom in February. Sverdrup critital depth euphotic theory is applied in the interpretation of these observations. Finally the model validation is achieved either through in situ data, or through climatic data, bringing to light a qualitative and quantitative agreement between model results and reality, for the physical variables as well as the biological ones.

Grantor dc:publisher

ULiège - Université de Liège

Year dc:date

2006

Author dc:creator

• Troupin, Charles

Contributors dc:contributor

• Sangrà, Pablo
• Facultad de Ciencias de Mar, University of Las Palmas de Gran Canaria

• ROMS 1D
• mixed layer
• Canary Islands
• KPP model
• Physical, chemical, mathematical & earth Sciences
• Earth sciences & physical geography
• Physique, chimie, mathématiques & sciences de la terre
• Sciences de la terre & géographie physique

Statement dc:rights

• open access
• info:eu-repo/semantics/openAccess

Licence

• http://purl.org/coar/access_right/c_abf2

Language dc:language

en

Identifier

info:hdl:2268/112587

OAI identifier oai:identifier

oai:orbi.ulg.ac.be:2268/112587