1. Frontier Research System for Global Change,
Preliminary results from the oceanic component of the integrated earth system model of Kyousei2
Michio KAWAMIYA
Chisato YOSHIKAWA
Maki NOGUCHI
Taroh MATSUNO
Frontier Research System for Global Change,
Yokohama, Japan

2. At the last steering committee meeting:
Results from a “flying leap” experiment
5 months later… (= This talk):
Performance check
Sensitivity to surface forcing
Projection of future CO2 uptake by the ocean
Incorporation into our coupled model (MIROC)
Schedule

3. Model outline OGCM: Code: COCO3.4 (Hasumi, 2000)
based on primitive equations
Resolution: 1 deg. X 1. deg.
54 vertical levels
(20 levels for the upper 100m)
Biological model:
Nitrogen based, 4-compartment model by
Oschlies & Garcon (1998) modified by
Oschlies (2001)
Carbonate system is incorporated following
the OCMIP protocol.

4. Comparative study between model-derived and reanalysis forcing fields (preparation for a global warming experiment)
Forcing fields (SST, P-E, wind stress, solar radiation) from:
OMIP data (ECMWF reanalysis)
CCSR/NIES coupled model output
Initial conditions
T, S: results from an OMIP experiment
Nitrate: World Ocean Atlas ’94
TCO2, Alkalinity: results from an OCMIP experiment
Other biological variables: constant (0.1 mmol/m3)
Spin-up: 20 years

5. Results
Surf. Chl.
Nitrate
Obs.
Reanalysis
Model-derived

6. Nutrient trap along the coast of Peru -- Reanalysis data are less realistic? --
Surf. Nitrate
Wind stress
W along the 15S
Reanalysis
風の場の差は、一見小さいことを指摘
Model-derived

7. Nitrate distribution in the Southern Ocean
Reanalysis
Nitrate
Model-derived
Ekman W
Reanalysis
Ekman W
Model-derived

8. Nitrate distribution in the Southern Ocean (2)
Mixed layer depth
WOA
Reanalysis
Model-derived

9. Nutrient distribution in the Southern Ocean (3)
P-E
SSS
WOA
Reanalysis
Model-derived

10. Air-sea exchange of CO2 Obs.(Takahashi et al.,1999) Reanalysis
Model-derived

11. Summary of the difference
Nutrient trapping off Peru due to strong coastal upwelling under the OMIP forcing
Low surface nitrate in the Southern Ocean under the model-derived forcing due to shallow mixed layer
The above difference is not reflected in the air-sea CO2 exchange field because of differences in the processes governing the surface concentrations of nitrate and fCO2

12. Earlier estimates of future uptake of anthropogenic CO2 by the ocean
IPCC TAR
OCMIP type models: simple representation of the
biological pump

13. Time evolution of atmospheric CO2
Gradual, linear increase up until 1990, then 1%/year increase

14. Air-sea exchange of CO2

15. Summary of the performance check
The experiments forced by reanalysis and model-derived data provide similar results regarding air-sea CO2 exchange.
The current and future ocean uptakes of CO2 estimate by the model are consistent with earlier results from models with simpler representation of the pelagic ecosystem.
Apparently, no bug. Go for it!
First results from a coupled carbon cycle model are expected early next year.

16. Carbon cycle model now incorporated in our coupled model
(T42L20 for atmosphere, ( )x1.4 for ocean)
Chlorophyll
Nitrate

17. Project Schedule

18. Participation in C4MIP
Coupled Climate－Carbon Cycle Model Intercomparison Project (IGBP/GAIM)
Phase 1 (~2004): Emphasis on terrestrial carbon cycle models
Phase 2 (~2005): Full coupled carbon cycle models