Title: Projection of ocean uptake of anthropogenic CO2 using an ocean carbon cycle model: Preliminary resul
1Projection of ocean uptake of anthropogenic CO2
using an ocean carbon cycle model Preliminary
results from the oceanic component of the
integrated earth system model at FRSGC
- Michio KAWAMIYA
- Chisato YOSHIKAWA
- Maki NOGUCHI
- Taroh MATSUNO
- Frontier Research System for Global Change,
- Yokohama, Japan
2Introduction
- Earlier estimates of future uptake of
anthropogenic CO2 by the ocean
IPCC TAR
OCMIP type models simple representation of the
biological pump
3Model 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)
4Comparative study between model-derived and
reanalysis forcing fields
- 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
5Results
Surf. Chl.
Nitrate
Obs.
Reanalysis
Model-derived
6Nutrient trap along the coast of Peru--
Reanalysis data are less realistic? --
Wind stress
Surf. Nitrate
W along the 15S
Reanalysis
Model-derived
7Nutrient trap (2)
8Nitrate distribution in the Southern Ocean (1)
Nitrate Reanalysis
Nitrate Model-derived
Ekman W Reanalysis
Ekman W Model-derived
9Nitrate distribution in the Southern Ocean (2)
Mixed layer depth
Nitrate
WOA
Reanalysis
Model-derived
10Nutrient distribution in the Southern Ocean (3)
P-E
SSS
WOA
Reanalysis
Model-derived
11Air-sea exchange of CO2
Takahashi Et al. (1999)
Reanalysis
Model-derived
12Summary 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
13Forcing for the global warming experiment
SST, wind stress, P-E, solar radiation outputs
from a global warming
experiement
with a coupled model
based on the
IS92a scenario
14Surface chl. fields
15Air-sea exchange of CO2
16Air-sea exchange of CO2
Takahashi Et al. (1999)
Reanalysis
Model-derived
17Current ocean models underestimate the ocean
response to climate variations?Suggestion from
inversion studies
Forward model (LeQuere et al. 2000)
Inversion results
18Intrusion of anthropogenic CO2
19Another group at FRSGC is working on a model with
multiple size classes of plankton.
20Some results from the model with multiple size
classes
21Summary
- 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.