evaluating the role of the co 2 source from co oxidation
DESCRIPTION
Evaluating the Role of the CO 2 Source from CO Oxidation. P. Suntharalingam Harvard University TRANSCOM Meeting, Tsukuba June 14-18, 2004. Collaborators : J. Randerson, J. A. Logan, D. J. Jacob, N. Krakauer, Y. Xiao, R. M. Yantosca,. - PowerPoint PPT PresentationTRANSCRIPT
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Evaluating the Role of the CO2 Source from CO Oxidation
P. Suntharalingam
Harvard University
TRANSCOM Meeting, Tsukuba
June 14-18, 2004
Collaborators : J. Randerson, J. A. Logan, D. J. Jacob, N. Krakauer, Y. Xiao, R. M. Yantosca,
Acknowledgements : NOAA OGP Global Carbon Cycle Program, NASA Carbon Cycle Program
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CARBON FLUX FRAMEWORK UNDERLYING MANY ATMOSPHERIC CO2 INVERSIONS
Fossil Biosphere Land use Change
Ocean
1.6 0.5
6120 120
Units = Pg C/yr
Atmospheric CO2
9092
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TROPOSPHERIC CO OXIDATION IS A SOURCE OF ATMOSPHERIC CO2
Fossil Biosphere, Land use change, Agriculture, Biomass burning
Ocean
ATMOSPHERIC CO2
ATMOSPHERIC CO
CO, CH4, NMHCs
0.9-1.2 Pg C/yr
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REDUCED CARBON GASES ARE ACCOUNTED FOR IN EMISSIONS INVENTORIES BUT EMITTED AS CO2
Fossil fuel : CO2 emissions based on carbon content of fuel and assuming complete oxidation of CO and volatile hydrocarbons.
(Marland and Rotty, 1984; Andres et al. 1996)
CASA neutral biosphere : Biospheric C efflux represents respiration (CO2) and emissions of reduced C gases (biogenic hydrocarbons, CH4,etc)
(Randerson et al. , 2002; Randerson et al. 1997)
CASA Neutral Biosphere
Fossil Fuel
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ANALYSIS FOCUS: Evaluating the “Chemical Pump” Effect IMPLICATIONS FOR FLUX ESTIMATES FROM CO2 INVERSIONS OF MODELING
REDUCED C CONTRIBUTION TO CO2 AT SURFACE RATHER THAN AT OXIDATION SITE IN TROPOSPHERE
STEP 1 : Evaluate impact on modeled concentrations
STEP 2 : Implications for atmospheric inversions and estimated fluxes
Previous related analyses : Enting and Mansbridge [1991]; Baker [2001]
CO2 from reduced C gases
VS.CO2 source from CO oxidation
Surface Source Tropospheric Source
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EVALUATION OF THE CHEMICAL PUMP EFFECTCalculate ADJUSTMENT zmodel to Model Concentrations
1) Flux estimates from atmospheric inversions are based on difference between modeled and observed CO2 concentrations : zmodel – zobs
2) Adjust zmodel to account for redistribution of reduced gas C from surface inventories to oxidation location in troposphere
3) Adjustmentzmodel = zCOox – zRedC
ADD effect of CO oxidation source of CO2
SUBTRACT effect of reduced C from surface inventories
Total carbon source conserved between zCOox and zRedC
simulations
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EVALUATION OF THE CHEMICAL PUMP EFFECTANALYSIS SETUP USING THE GEOS-CHEM MODEL
Standard Simulation
CO2 Source from CO Oxidation = 1.1 Pg C/yr
Distribute source according to seasonal 3-D
variation of CO2 production from CO
Oxidation
Distribute source according to seasonal SURFACE variations of reduced C emissions from Fossil and Biosphere sources
CO2RedC SimulationCO2COox Simulation
Simulations spun up for 3 years. Results from 4th year of simulation
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The GEOS-CHEM Modelhttp://www-as.harvard.edu/chemistry/trop/geos/index.html
•Global 3-D model of atmospheric chemistry
•2ox2.5o horizontal resolution; 30 vertical levels
•Driven by assimilated meteorology (GMAO)
• The CO simulation run to obtain CO oxidation distribution relies on archived OH fields (monthly)
Emissions Distributions (spatial and temporal variability)
Fossil : Andres et al. [1996] (annual mean)
Biomass Burning : Duncan et al. [2003] (monthly)
Biofuels : Yevich and Logan [2003] (annual mean)
Biogenic hydrocarbons : Duncan et al. [2004], based on Guenther et al. [1995] (monthly)
CH4 emissions distributions : A priori from Wang et al. [2004] (monthly)
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GLOBAL CO BUDGETSOURCES Duncan et al. 2004
Tg CO Pg CRecent Inverse
Analyses*
COMBUSTIONFossilBiomass BurningBiofuelsTOTAL
465-490450-570
190 1105-1250 0.47 –0.55
* Bergamaschi et al. [2000]; Petron et al. [2002]; Kasibhatla et al. [2002]
1100-1530 0.47-0.65
BIOGENICSIsoprene, Monoterpenes, etc.
350-370 0.15-0.16 510-660 0.22-0.28
CH4 OXIDATION 840-915 0.36-0.39 740-830 0.32-0.35
TOTAL 2290-2540 0.9-1.1 2846-3067 1.2-1.3
SINKS : Oxidation by OH
STANDARD SIMULATION :CO2 source from CO oxidation of 1.1 Pg C/yr
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REDUCED CARBON SOURCES BY SECTOR STANDARD SIMULATION : CO2 Source from CO Oxidation = 1.1 Pg C/yr
* Methane sources distributed according to a priori fields from Wang et al. [2004]
REDUCED CARBON SOURCES Pg C/yr
Fossil (CO,CH4,NMHCs) 0.27
Biomass Burning (CO,CH4,NMHCs) 0.26
Biofuels (CO,CH4) 0.09
Biogenic Hydrocarbons 0.16
Other Methane Sources* 0.31
TOTAL 1.1
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CH4 EMISSIONS AND BUDGET PROPORTIONS
Rice
Livestock
Wetlands
Termites
BiomassBurn
Fossil
Landfills
Biofuel
Standard Simulation :CH4 Oxidation to CO = 0.39 Pg C/yr
CH4 emissions distributions and budget proportions from the a priori distribution of Wang et al. [2004]
Rice 11%
Wetlands 36%
Termites 5%
Biomass Burning 4%
Fossil 16%
Landfills 10%Biofuel 2%
Livestock 11%
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Source Distributions : Annual Mean
Zonal Integral of Emissions
Latitude
CO2COox: Column Integral of
CO2 from CO OxidationCO2RedC :CO2 Emissions from
Reduced C Sources
CO2COox :Maximum in tropics, diffuse
CO2RedC : Localized, corresponding to regions of high CO, CH4 and biogenic NMHC emissions
CO2COox
CO2RedC
gC/(cm2 yr)
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SURFACE CONCENTRATIONS : Annual Mean
CO2RedC
DmodelCO2
CO2COox
Chemical Pump Adjustment
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ZONAL AVERAGE : CHEMICAL PUMP EFFECT
DmodelCO2 at
Surface
CO
2 (p
pm
)
Mean Interhemispheric
difference = - 0.21 ppm
0.8 ppm
Fossil : Surface, annual mean
1 Pg Fossil fuel CO2 source gives interhemispheric difference of 0.81 ppm at surface, in GEOS-CHEM model
0.21 ppm
Latitude
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CHEMICAL PUMP EFFECT AT GLOBALVIEW SITES USED IN TRANSCOM LEVEL 1 INVERSION
TRANSCOM Level 1 Inversion residuals from Gurney et al. 2002
Mean interhemispheric difference at TRANSCOM sites = 0.2 ppm
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REGIONAL VARIATION OF CHEMICAL PUMP EFFECT
Largest changes in regions in and downstream of high reduced C emissions
TAP : - 0.55; ITN : - 0.35; BAL : - 0.35 (ppm)
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IMPACT ON SURFACE FLUX ESTIMATES
INTERHEMISPHERIC DIFFERENCE AT
GLOBALVIEW SITES (ppm)
DECREASE IN NHEM LAND CO2
UPTAKE(Pg C/yr)
Standard Simulation - 0.2 0.2
High CO (Petron et al. 2002)Increased Fossil+Biofuel emissions of 0.12 Pg C/yr
- 0.27 0.3
Preliminary inversion results from J. Randerson, N. Krakauer
TRANSCOM Level 1 inversion MATCH model
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SUMMARY
•The atmospheric chemical pump has important implications for modeled CO2 concentrations and inversion flux estimates.
•A CO oxidation source of 1.1 Pg C/yr gives a reduction in the modeled annual mean N-S gradient of 0.2 ppm (equivalent to a reduction of 0.2 Pg C/yr in Northern Hemispheric land uptake in an annual mean inversion.)
•Regional changes are larger; up to 0.6 ppm in regions of high reduced C emissions.
•Seasonal variations and sensitivities to model assumptions will be explored in future work.
•We can provide the reduced C source distributions (3D and surface) to TRANSCOM modelers to calculate their own model-specific chemical pump adjustments.