1. Correlation of CO-HCN-C 2 H 2 -C 2 H 6 : Global Constraints on Combustion Sources Biomass burning Biofuels Natural gas/coal C2H6C2H6 ~2 mon CO Fossil fuel combustion Auto combustion C2H2C2H2 ~2 mon~2 wks uptake HCN ~5 mon ocean Yaping Xiao Atmospheric Chemistry Modeling Group Harvard University

2. Observed correlation of CO-HCN-C 2 H 2 -C 2 H 6 FTIR column measurementsShip cruises

3. Key questions:  What do the correlations imply? Are they consistent with our current understanding of sources?  How can we use them to constrain source terms?  What constraints can C 2 H 2 -CO correlation provide on OH concentration? Model analysis of CO-HCN-C 2 H 2 -C 2 H 6 system Tasks:  Improve understanding of global C 2 H 2 budget  Constrain regional OH concentration using C 2 H 2 /CO relationship  Improve understanding of HCN oceanic sink with the new column data in Southern Hemisphere  Interpret column and aircraft data in terms of constraining sources using forward model analysis of CO-HCN-C 2 H 2 -C 2 H 6 system

4. C 2 H 2 preliminary emission inventory totalffbfbboceanic EDGAR 3.24 Gupta et al.[1998]3.1 Gautrois et al.[2003]8.8 Blake et al.[1996]2.1/2.8 Kanikiou et al.[1988]0.2~1.4 Plass et al.[1992]Very small Plass-Dulmer et al.[1993]0.16~0.54 This work4.21.11.51.6?0.53 Asia Streets et al.[2003]0.91.3 This work0.250.880.45

5. Evaluation of C 2 H 2 with seasonal variation NA bf & Streets in Asia With NA bf Preliminary Arctic Europe NA Tropical Pacifc

6. C 2 H 2 : Tropical pacific Pem-TA (Sep) Pem-TB(Mar)

7. Constrain sources using C 2 H 2 /CO Trace-P China CoastS ChinaCoastSJapan CO C2H2C2H2

8. Constrain OH using C 2 H 2 /CO correlation Trace-P Pemw-a

9. HCN: Two different oceanic sink parameterizations constant seawater conctr. (xyp) uniform saturation ratio (qli) LauderAntarctic The model with constant seawater HCN conctr. improves comparison in SH

10. Southern Ocean is not a sink for HCN? HCNCO Antarctic Obs Model Lauder Obs Model

11. CO yield from CH 4 oxidation in tagged CO model  Mean yields in austral winter at SH mid and high latitudes are 0.81-0.86, otherwise about 0.95  With modified yield, mean bias in tagged CO at southern high latitudes decreases from 9 to 6 ppb in May-Aug.

12. C 2 H 6 emission inventory: Streets vs. standard  Standard GEOS-CHEM: ff scaled from CH 4  Streets: Streets ff/bf in Asia, elsewhere increased by 30% C 2 H 6 (Tg/yr) ffbfbb Standard 8.4 (2.4) 2.0 (1.5) 2.0 Streets 10.1 (0.8) 2.0 (1.5)

14. CO: SH mid/high latitude problem Model CO at 45S-90S is overestimated by ~15 ppb in full chem  Mean yields in austral winter at SH mid and high latitudes are 0.81-0.86  With yield update in tagged CO model, bias decreases from 9 to 6 ppb in May-Aug.  How can this be accounted for in full chemistry simulation? CO yield from CH4 amf v4-33 mje v5-07-08 xyp tagged v4-33 OH rvm v4-26 1997