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PISCES (Pelagic Interactions Scheme for Carbon and Ecosystem Studies) model

PISCES (PEES-kays, /ˈpiːs.keːs/) is a high complexity ocean biogeochemical model with 24 prognostic tracers. It has previously been used with the NEMO transport model in the IPSL-CM5A-LR and CNRM-CM5 CMIP-5 earth system models (ESM). This is an early attempt to implement PISCES for use as a test bed in a more flexible environment to allow rapid prototyping and testing of new parametrisations as well as use in idealised experiments, additionally we want to be able to replicate the dynamics of the operational model for possible future use in a Julia based ESM as the ecosystem matures.

An overview of the model structure is available from the PISCES community website:

PISCES model structure

The default configuration of PISCES in OceanBioME is the operational/standard version with 24 tracers and can be set up by writing:

using OceanBioME, Oceananigans

grid = RectilinearGrid(size=(1, 1, 1), extent=(1, 1, 1));

biogeochemistry = PISCES(; grid)

show(biogeochemistry)

Oceananigans.Biogeochemistry.required_biogeochemical_tracers(biogeochemistry)

(:P, :PChl, :PFe, :D, :DChl, :DFe, :DSi, :Z, :M, :DOC, :POC, :GOC, :SFe, :BFe, :PSi, :CaCO₃, :NO₃, :NH₄, :PO₄, :Fe, :Si, :DIC, :Alk, :O₂, :T, :S)
(:P, :PChl, :PFe, :D, :DChl, :DFe, :DSi, :Z, :M, :DOC, :POC, :GOC, :SFe, :BFe, :PSi, :CaCO₃, :NO₃, :NH₄, :PO₄, :Fe, :Si, :DIC, :Alk, :O₂, :T, :S)

The parametrisations can easily be switched out when the biogeochemistry is constructed by setting the key word parameter, see the API documentation, although we currently do not have any of the other configurations implemented. Note that PISCES-simple is very similar to LOBSTER if that is what you are looking for.

More documentation will follow but for now the equations can be found in Aumont et al. (2015) read along side our notes here.

Model conservation

When the permanent scavenging of iron, nitrogen fixation, and particle sinking are turned off, PISCES conserves:

  • Carbon: $\partial_tP + \partial_tD + \partial_tZ + \partial_tM + \partial_tDOC + \partial_tPOC + \partial_tGOC + \partial_tDIC + \partial_tCaCO_3=0$
  • Iron: $\partial_tPFe + \partial_tDFe + \theta^{Fe}\left(\partial_tZ + \partial_tM + \partial_tDOC\right) + \partial_tSFe + \partial_tBFe + \partial_tFe=0$
  • Phosphate: $\theta^P\left(\partial_tPFe + \partial_tDFe + \partial_tZ + \partial_tM + \partial_tDOC + \partial_tPOC + \partial_tGOC\right) + \partial_tPO_4=0$
  • Silicon: $\partial_tDSi + \partial_tPSi + \partial_tSi=0$
  • Nitrogen: $\theta^N\left(\partial_tPFe + \partial_tDFe + \partial_tZ + \partial_tM + \partial_tDOC + \partial_tPOC + \partial_tGOC\right) + \partial_tNH_4 + \partial_tNO_3=0$