Boxes indicate state variables, and solid arrows represent fluxes between state variables; dashed lines indicate that the rate of change of one state variable is calculated proportionately to another. Colors indicate the base element for each state variable, with blue, green, pink, orange, and gray representing nitrogen, phosphorous, silicon, iron, and carbon, respectively. State variable boxes are positioned vertically based on functional role, indicating whether the functional group includes producers (and within that, subcategories of nitrogen fixers, Si-users, and CaCO3-users), consumers, or detritus. Horizontal position indicates the approximate mean size of the cells/bodies/particles represented by each state variable.
Figure 3: Schematic of the CSIRO Environmental Modelling Suite illustrating the biogeochemical processes in the water column, epipelagic and sediment zones, as well as the carbon chemistry and gas exchange used in vB3p0 for the Great Barrier Reef application. Orange labels represent components that scatter or absorb light.
it is my understanding that Bling is simpler than WOMBAT or at least would not be an improvement on WOMBAT. COBALT is much more complex and could be a next step forward if computational resources allow
Yes, Bling is simple and parameterises productivity and export, it doesn’t even carry phyto-/zoo- plankton tracers (see schematic above).
COBALT or TOPAZ have interesting new capabilities. While GFDL versions of MOM6 are being tested, it should be straight forward to turn these tracer packages on; there are test cases with prepared boundary conditions(?) (It will be more complicated once MOM6 is coupled to CICE#.)
Personally, I think there is value in developing WOMBAT “in-house”, rather than using COBALT or others as our national BGC model. The reason for this is three-fold:
It ensures we know the model we are using. There are no unexplainable results.
It ensures we develop BGC capability that caters to the Australian scientific community.
It ensures that Australia has BGC capability for naval operations that doesn’t rely on the tools of other countries.
This of course doesn’t mean that we can’t use COBALT when we want to.
I’m going to write out some key developments I want to make as the new BGC modeller at CSIRO, and I will add collaborators names here who have expressed interest in being closely involved in the developments steps.
Major renovations to the Fe cycle (Alessandro Tagliabue)
Explicit N2O dynamics
Quota approach for N and P (non-Redfieldian ratios)
Two DOM classes (semi-labile and semi-relcalcitrant)
N, O and C isotopes
Explicit bacterial types (copiotrophs and oligotrophs)
If you wish to follow the developments as I make them, please follow this Github repository. I plan to do the initial development steps in a 1D water column set-up I just wrote in python. I plan to upload jupyter notebooks detailing the developments as I go, so you should be able to see changes caused by adding new phytoplankton classes and by considering different grazing parameterisations, for example.