1. 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 Group Harvard University June, 2002 OBJECTIVE: use a global 3-D model interpretation of the CH 4 -C 2 H 6 -CO correlations observed in TRACE-P as constraints on the sources of these gases

2. Observed correlations C 2 H 6 -CH 4 CO-C 2 H 6

3. GEOS-CHEM C 2 H 6 simulation during TRACE-P 4x5 horizontal resolution, 48 vertical levels Monthly OH from full chemistry simulation(CH 3 CCl 3 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 GlobalAsiaAsia* Natural gas leakage scaled to the corresponding sources of CH 4 [J.Wang, 2002, Fung et al., 1991] Uniform mass ratio of C 2 H 6 /CH 4 : 8% 3.0 1.730.58 Natural gas venting0.8 Coal mining2.5 Biomass burning Scaled to CO BB emission [Duncan et al., 2001] w/ seasonal variation 2.00.620.60 Biofuel use Inventory: Yevich and Logan [2001] EF: Andreae and Merlet [2001] 2.01.241.22 * D. Streets inventory

4. The model has a distinct bias in the boundary layer European industrial source has large influence in Asian outflow

5. ObservationModel 22.2 6.7 25.0 6.3 21.4 6.5 27.3 6.2 Streets Logan Bb 0.6/2/(70*12/28) =20 ~5.5 Bf 1.22/2/(104*12/28) =32 ~20. Ind. 0.58/2/(70*12/28) =22 Asian C 2 H 6 /CO emission ratio (moleC 2 H 6 /moleCO*10 -3 ) Free Troposphere Boundary Layer C 2 H 6 -CO correlation

6. Preliminary inventory of CH 4 sources Animals Gas venting Gas leakage Landfills Coal mining Termites Soil sink Rice paddies Wetlands Biomass burning

7. Application of CH 4 simulation to TRACE-P ? Background CH 4 Initiate the model with observed latitudinal distribution from CMDL

8. 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