1. National Oceanography Centre, UK
Modelling beauty contest 
Katya Popova
National Oceanography Centre, UK 1

2. UK Earth System Modelling (ESM) Implementation
Delivers UK contribution to CMIP6 (IPCC AR6)
Core Group
(MetOffice/NERC)
Assemble
Run
Analysis

3. Marine Biogeochemistry
UK Earth System Modelling (ESM) Implementation
Delivers UK contribution to CMIP6 (IPCC AR6)
Core Group
(MetOffice/NERC)
Assemble
Run
Analysis
Ice Sheets/Shelves
(BAS, Bristol)
Atmosphere
(NCAS, Met O)
Land Surface (CEH)
Marine Biogeochemistry
(NOC, Met O)
Sea-Ice
(NOC,BAS, CPOM, Met O)
Ocean Group

4. Marine Biogeochemistry
UK Earth System Modelling (ESM) Implementation
Delivers UK contribution to CMIP6 (IPCC AR6)
Core Group
(MetOffice/NERC)
Assemble
Run
Analysis
Ice Sheets/Shelves
(BAS, Bristol)
Atmosphere
(NCAS, Met O)
Land Surface (CEH)
Marine Biogeochemistry
(?, Met O)
Sea-Ice
(NOC,BAS, CPOM, Met O)
Ocean Group
(NOC, Met O) ?

5. iMARNET project National Oceanography Centre Plymouth Marine Laboratory University of East Anglia Met Office
A. Yool, E. Buitenhuis, M. Butenschon,
L. de Mora, C. Enright, P. Halloran,
B. Sinha, I. Totterdell

6. iMARNET project National Oceanography Centre Plymouth Marine Laboratory University of East Anglia Met Office
“Beauty contest”
A. Yool, E. Buitenhuis, M. Butenschon,
L. de Mora, C. Enright, P. Halloran,
B. Sinha, I. Totterdell

7. iMARNET project “Beauty contest”
To select ocean biogeochemistry for the UK Global Earth System model for the contribution to the next IPCC AR6 (~2019).
Criteria:
Computational efficiency (Ocean model resolution 1/4o )
Best agreement with global climatological data sets:
Dissolved inorganic nitrogen
Silicate
Chl-a
Primary production
Inorganic carbon
Alkalinity
Minimum additional complexity:
The model should be able to perform iron fertilisation experiment (Fe)

8. Participant biogeochemical models HadOCC Diat-HadOCC MEDUSA-2
PLANKTOM-10 +
simpler siblings
ERSEM

9. Plankton functional types
HadOCC
Diat-HadOCC
MEDUSA-2
PlankTOM-5
PlankTOM-10
ERSEM
Generic P. √
Diatoms
“Large P.”
Picophyto.
Coccos ?
N2-fixers
Flagellates
Phaeocystis
Generic Z.
Microzoo.
Mesozoo.
Macrozoo.
Het. nanoflag.
Bacteria
Tracers 7 13 15 25 39 57

10. iMARNET benchmarking Model BGC tracers 128 (CPU s) Fraction 256 (CPUs)
Physics-only
55169 -
108366
HadOCC 7
96371
1.75
160733
1.48
Diat-HadOCC 13
130102
2.36
203680
1.88
MEDUSA-2 15
150672
2.73
227153
2.10
PlankTOM-6 25
281898
5.11
381472
3.52
PlankTOM-10 39
427026
7.74
529862
4.90
ERSEM 57
571395
10.36
744285
6.87

11. The main conclusion: We find little evidence that more complex models evaluate better against observations and often the opposite is the case

12. ? =
Miss World Ocean
Miss Arctic

23. Conclusion: Concluding remarks
Time for metric development! Can we develop a metric which would separate upstream problems (Pacific and Atlantic) from AO problems? Time to move beyond climatology?

24. Arctic is not under-sampled,
it is under-modelled!

25. IPCC AR6 timeline
Ecosystem model selected: Summer 2013
Model coupled to the ESM, fine-tuned and frozen: Summer 2015
Equilibration runs, scenarios: Autumn 2017
Analysis (papers submitted): Summer 2018
AR6 - Autumn 2019