Abstract
Abstract. PISCES-v2 (Pelagic Interactions Scheme for Carbon and Ecosystem Studies volume 2) is a biogeochemical model which simulates the lower trophic levels of marine ecosystems (phytoplankton, microzooplankton and mesozooplankton) and the biogeochemical cycles of carbon and of the main nutrients (P, N, Fe, and Si). The model is intended to be used for both regional and global configurations at high or low spatial resolutions as well as for short-term (seasonal, interannual) and long-term (climate change, paleoceanography) analyses. There are 24 prognostic variables (tracers) including two phytoplankton compartments (diatoms and nanophytoplankton), two zooplankton size classes (microzooplankton and mesozooplankton) and a description of the carbonate chemistry. Formulations in PISCES-v2 are based on a mixed Monod–quota formalism. On the one hand, stoichiometry of C / N / P is fixed and growth rate of phytoplankton is limited by the external availability in N, P and Si. On the other hand, the iron and silicon quotas are variable and the growth rate of phytoplankton is limited by the internal availability in Fe. Various parameterizations can be activated in PISCES-v2, setting, for instance, the complexity of iron chemistry or the description of particulate organic materials. So far, PISCES-v2 has been coupled to the Nucleus for European Modelling of the Ocean (NEMO) and Regional Ocean Modeling System (ROMS) systems. A full description of PISCES-v2 and of its optional functionalities is provided here. The results of a quasi-steady-state simulation are presented and evaluated against diverse observational and satellite-derived data. Finally, some of the new functionalities of PISCES-v2 are tested in a series of sensitivity experiments.
Highlights
Human activities have released large amounts of carbon into the atmosphere since the beginning of the industrial era leading to an increase in atmospheric CO2 by more than 100 ppmv
Following Flynn and Hipkin (1999), we assume that the rate of synthesis by the cell of new components requiring iron is given by the difference between the iron quota and the sum of the iron required by these three sources of demand, which we defined as the actual minimum iron quota: θmFein,I
In PISCES, we model this process following the approach chosen for dissolved organic matter (DOM): Cgfe1 = ((a1DOC + a2POC) × sh + a4POC +a5DOC) × Fecoll, Cgfe2 = a3GOC × sh × Fecoll, (61a) (61b) where Fecoll is computed from the iron chemistry model
Summary
Human activities have released large amounts of carbon into the atmosphere since the beginning of the industrial era leading to an increase in atmospheric CO2 by more than 100 ppmv. PISCES (Pelagic Interactions Scheme for Carbon and Ecosystem Studies) is a biogeochemical model which simulates marine biological productivity and describes the biogeochemical cycles of carbon and of the main nutrients (P, N, Si, Fe) This model can be seen as one of the many Monod models (Monod, 1942) as opposed to the quota models (McCarthy, 1980; Droop, 1983) which are alternative types of ocean biogeochemical models. This served to justify the development, beginning in 1999, of a more complex model that includes three limiting nutrients (Fe, Si, P), two phytoplankton and two zooplankton size classes This model was called HAMOCC5 (Aumont et al, 2003), as it was based on HAMOCC3.1 (Six and MaierReimer, 1996) and used in the LSG model (Maier-Reimer et al, 1993). The impact of several new parameterizations is evaluated through the performance of a set of sensitivity experiments
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