1. Icarus Allen, Tom Anderson, Corinne le Quéré
Integrated Marine Biogeochemical Modelling Network to Support UK Earth System Research (the 'i-MarNet')
i-MarNet aims to provide a framework and pathway for the development of a
new biogeochemical model/model hierarchy for use by the UK science community
Icarus Allen, Tom Anderson, Corinne le Quéré

2. Rationale for i-MarNet
Ocean Biogeochemistry is an important part of the Earth System regulating the global cycle of C, N, P and providing a source of climatically active gases.

3. Rationale for i-MarNet
The UK is a world leader in marine biogeochemical / ecosystem modelling with a diversity of models and range of expertise.
If we are to maintain UK leadership in this field it is essential that the UK ESM community works together in a coordinated way that more effectively exploits the strengths of the Met Office and the NERC community.

4. Rationale for i-MarNet
MEDUSA
PlankTOM10
NanoPhyto Si
Diatoms Fe N
MesoZoo
MicroZoo
slow
detritus
Fast particle
flux
HadOCC
nutrient
phyto-
plankton
zoo-
detritus
Diat-HadOCC
ERSEM
Increasing structural complexity

5. Rationale for i-MarNet
NERC ESM Strategy:
to develop a new, unified, biological modelling approach that builds on the strength of existing models
to provide a traceable hierarchy of models of different complexity using a modular approach with consistent process descriptions through a coordinated initiative by the wider UK community

6. Rationale for i-MarNet
A more coordinated strategy for UK model development will help to
improve the models,
help identify key uncertainties,
and ensure compatibility with parallel efforts (e.g. in shelf seas modelling).

7. Rationale for i-MarNet
A more coordinated strategy for UK model development will help to
improve the models,
help identify key uncertainties,
and ensure compatibility with parallel efforts (e.g. in shelf seas modelling).
Recognise importance of appropriate approaches for different problems
Need to understand the relationship between models of different complexity
Use of common frameworks to facilitate pull through from research to core strategic modelling tools

8. Complexity
Phytoplankton
Nutrient
Zooplankton
Detritus

9. Complexity Si N P Fe multiple zooplankton multiple PFTs multiple slow
Phytoplankton
Nutrient
Zooplankton
Detritus
multiple
nutrients Si N P Fe
fast
sink
slow
spectrum
of size
classes
These models can become muddles. Useful heuristic tools.

10. Increasing structural complexity
MEDUSA
PlankTOM10
NanoPhyto Si
Diatoms Fe N
MesoZoo
MicroZoo
slow
detritus
Fast particle
flux
HadOCC
nutrient
phyto-
plankton
zoo-
detritus
Diat-HadOCC
ERSEM
Increasing structural complexity

11. v v v v Complexity high light high N:P low Si
Poorly understood ecology
Umbellosphaera tenuis
Florisphaera profunda
Gephyrocapsa ericsonii v
Aggregation v
All in the interactions v
Data, validation

12. Predicted diatom distributions
Complexity
Predicted diatom distributions
March-May
Sept.-Nov.
NEMO
OCCAM
Sinha et al. (2010)

13. Complexity

14. 3 Phase project
Phase 1: i-MarNet will establish a community of stakeholders, model developers and model users to help determine the biogeochemical model hierarchy needed by the UK science community.
Phase 2: i-MarNet will undertake a comparison of existing UK global biogeochemical models to provide a systematic body of evidence by spring 2013 to inform UKMO model selection for the next IPCC assessment.
Phase 3: i-MarNet will define a roadmap for the development of the next generation ocean biogeochemical model in terms of specific areas to be addressed and possible approaches, and requirements for analytical tools to quantify model skill and demonstrate traceability

15. Phase 1: Establishing the Network
Role: Inform the inter-comparison experiment, devise the roadmap
Diverse membership
Biologists
Modellers
Bio geochemists
Computer scientists
Mathematicians
Climate scientists
Three key workshops
Biological assessments
Skill assessment
Roadmap
Model evaluation projects
3 X 15K sub contracts
Open call
Potential Network Members
Core member iMarNet
Project partner
Written expression of interest
Verbal expression of interest

16. Phase 2: Comparison of existing models
HadOCC, diat-HadOCC,
MEDUSA, ERSEM, PlankTOM
Common Computing Platform
Monsoon
Common Physics
1 degree Global NEMO
Common Forcing
CORE ( )
UKMO RCP8.5 ( )
Common Initial Conditions*
World Ocean Atlas
*where possible

17. Expert assessment of biological fidelity Independent assessment
Phase 2: Assessment
Validation Data
Computational cost
Expert assessment of biological fidelity
3. Model Skill Assessment of C cycle
Univariate Metrics (R2, RMSE, Bias etc..)
Relationships (e.g. pCO2 vs T)
Spatial scales (wavelet analysis)
Pdf’s
Independent assessment
Network evaluation projects
Independent report (P Cox)
5. Synthesis
Reanalysis Hindcast

18. Phase 3: Road map for the next generation
Goal: to establish the vision for the next generation Ocean biogeochemistry model.
Drawing line in the sand but building on
on existing efforts we will establish
the vision for a 5-10 yr. model
development program.
Address range of issues:
Exploit state of the art knowledge
Traceable hierarchy
Novel modelling approaches
Parameter uncertainty
Software frameworks