Asian Sources of Methane and Ethane
Y. Xiao, D.J. Jacob, J. Wang, G.W. Sachse, D.R. Blake, D.G. Streets, et al.
Atmospheric Chemistry Modeling GroupHarvard University
June, 2002
OBJECTIVE: use a global 3-D model interpretation of the CH4-C2H6-CO correlations observed in TRACE-P as constraints on the sources of these gases
Observed correlations
C2H6-CH4 CO-C2H6
GEOS-CHEM C2H6 simulation during TRACE-P
• 4x5 horizontal resolution, 48 vertical levels
• Monthly OH from full chemistry simulation(CH3CCl3 lifetime ~ 5.6 years)
• Driven by DAO assimilated meteorological data during TRACE-P
Sink: reaction with OH, lifetime: 1-3 months
Model setup:
Asian emissions are superimposed with Y2K D. Streets emissions
Sources Global
Asia Asia*
Natural gas leakage scaled to the corresponding sources of CH4
[J.Wang, 2002, Fung et al., 1991]Uniform mass ratio of C2H6/CH4: 8%
3.0
1.73 0.58Natural gas venting
0.8
Coal mining 2.5
Biomass burning Scaled to CO BB emission [Duncan et al., 2001] w/ seasonal variation 2.0 0.62 0.60
Biofuel useInventory: Yevich and Logan [2001] EF: Andreae and Merlet [2001]
2.0 1.24 1.22* D. Streets inventory
The model has a distinct bias in the boundary layer
European industrial source has large influence in Asian outflow
ObservationModel22.2
6.7
25.0
6.3
21.4
6.5
27.3
6.2
Streets Logan
Bb0.6/2/(70*12/28)
=20~5.5
Bf 1.22/2/(104*12/28)=32
~20.
Ind.
0.58/2/(70*12/28)=22
Asian C2H6/CO emission ratio
(moleC2H6/moleCO*10-3)
Free
Troposphere
Boundary
Layer
C2H6-CO correlation
Preliminary inventory of CH4 sources
Animals
Gas ventin
g
Gas leakage
Landfills
Coal miningTerm
ite
sSoil s
inkRice
paddiesWetland
sBiomass
burning
Application of CH4 simulation to TRACE-P
? Background CH4
Initiate the model with observed latitudinal distribution from CMDL
Work to do
Higher horizontal resolution: 2x2.5
Tagged tracer simulation: quantify the contributions of different source regions and source types
To interpret discrepancies in terms of errors in individual source terms