fabm_particle

[jornbr]

@jornbr Hi Jorn!I m a new fabm user.I left you a message on Researchgate, I would like to ask you if there is a way to treat the plankton in the npzd model as a particle, I have tried applying fabm_particle but in the .nc file (output result) there is no difference with not applying fabm_particle. I am using the getm model. Cheers!

Originally posted by @RuoLinCunJi in https://github.com/fabm-model/fabm/issues/22#issuecomment-1226013852

[jornbr]

It is not exactly clear to me what you mean by "treat as a particle". If you mean you would like to have multiple plankton "particles" to be transported in Lagrangian fashion, as in an (super-)Individual Based Model, then the answer is that this would require support at the level of the hydrodynamic model. As far as I am aware, only GOTM has an experimental, not currently maintained branch that supports Lagrangian particles with behavior (growth etc.) specified by FABM.

It is worth describing briefly what the fabm_particle module is about: this is designed to make it easier to build modular ecosystem/biogeochemical models in which each module describes as set of quantities that physically belong together (e.g., carbon, nitrogen, phosphorus that together make up the biomass of some organism). If your module inherits from type_particle_model, it becomes possible to couple to other such particles and ask them for their total carbon, nitrogen, etc., or for the full set of all their state variables. This makes it possible to couple to other models without having to micromanage variable names in fabm.yaml. An example of a FABM-model that uses this functionality is ERSEM. But inheriting from fabm_particle would not turn your model in a Lagrangian model - this cannot be done at FABM level alone, but needs support in the host.

[RuoLinCunJi]

Dear Jorn Thank you very much for your patient answer, I would like to ask you, is there some way to achieve particle tracking of phytoplankton? Cheers R.Lin

[jornbr]

That's equivalent to the Lagrangian/Individual Based Model approach described above. It would require:

• support in the hydrodynamic model (e.g., GETM) to maintain and track particles, or alternatively, an offline particle tracking tool that reads in currents/diffusivities from file
• a mechanism to ascribe behavior (growth, death, etc.) to those particles. For that part, FABM could be used.

However, I am not aware of any hydrodynamic model or offline particle tracing tool that allows FABM to be used to prescribe particle behavior, other than the experimental GOTM branch I referred to above. So the short answer is, no, not to my knowledge.

Best,

Jorn

[RuoLinCunJi]

Dear Jorn Thank you for your guidance, and again for your detailed and patient answers！ Best wishes R.Lin