A prototype Carbon Cycle Data Assimilation System CCDAS

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A prototype Carbon Cycle Data Assimilation System
(CCDAS)

• Inferring interannual variations of
  vegetation-atmosphere CO2 fluxes

Marko Scholze1, Peter Rayner2, Wolfgang Knorr3,
Thomas Kaminski4, Ralf Giering4
presenting
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Carbon Cycle Data Assimilationusing automatic
differentiation

• 1. Parameter Optimisation
• Forward Parameters gt Misfit
• Adjoint or Tangent linear
  ? Misfit / ? Parameters
• 2. Parameter Uncertainties
• Hessian ?2 Misfit / ? Parameters2
• Error covarianceInverse of Hessian
• 3. Uncertainty of Diagnostics
• Adjoint or Tangent linear

Biosphere Model BETHY
Atmospheric Transport Model TM2
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CCDAS Setup
Assimilated
Prescribed
Assimilated
CO2 Uncert.
Phenology Hydrology
veg. index Satellite
CCDAS Step 2 IMBETHYTM2 only Photosynthesis,
EnergyCarbon Balance
CCDAS Step 1 full BETHY
Background CO2 fluxes
Calibrated Params Uncert.
Diagnostics Uncert.

ocean Takahashi et al. (1999), LeQuere et al.
(2000) emissions Marland et al. (2001), Andres
et al. (1996) land use Houghton et al. (1990)0
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BETHY(Biosphere Energy-Transfer-Hydrology Scheme)
?lat, ?lon 2 deg

• GPP
• C3 photosynthesis Farquhar et al. (1980)
• C4 photosynthesis Collatz et al. (1992)
• stomata Knorr (1997)
• Raut
• maintenance respiration f(Nleaf, T) Farquhar,
  Ryan (1991)
• growth respiration NPP Ryan (1991)
• Rhet
• fast/slow pool resp. wk Q10 T/10 C fast/slow /
  t fast/slow
• slow gt infin.
• average NPP b average Rhet (at each grid point)

?t1h
?t1h
?t1day
blt1 source bgt1 sink
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Concentrations
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Parameters
examples
relative error reduction
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Processes 1
global fluxes
Carbon sink GPP slightly exceeds respiration
Carbon source anomaly drop in GPP exceeds drop
in resp
Carbon sink anomaly stronger decr. in resp. than
GPP
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Processes 2
normalized CO2 flux and ENSO
ENSO and terr. biosph. CO2 correlation seems
strong
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Processes 3
El Niño (gt1s) net CO2 flux to atm. gC / (m2
month)
lagged correlation at 99 significance
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Carbon Balance
Euroflux (1-26) and other eddy covariance sites
net carbon flux 1980-2000 gC / (m2 year)
from Valentini et al. (2000) and others
latitude N
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Conclusions

• CCDAS with 58 parameters can already fit 20 years
  of CO2 concentration data
• Significant reduction of uncertainty for 13
  parameters, some important covariances
• terr. biosphere response to climate fluctuations
  dominated by ENSO and Pinatubo
• Can be explained by small perturbations of 3
  large fluxes (GPP, Raut, Rhet)

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Outlook

• explore more parameter configurations
• include fire as a process with uncertainties
• include more constraints (isotopes, eddy fluxes)
• extend approach to ocean carbon cycle