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Hongyu Liu, Daniel J. Jacob, Isabelle Bey, Robert M. Yantosca, Bryan N. Duncan

Transport pathways for Asian combustion outflow over the Pacific: Interannual and seasonal variations. Hongyu Liu, Daniel J. Jacob, Isabelle Bey, Robert M. Yantosca, Bryan N. Duncan Atmospheric Chemistry Modeling Group, Harvard University and Glen W. Sachse NASA Langley Research Center

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Hongyu Liu, Daniel J. Jacob, Isabelle Bey, Robert M. Yantosca, Bryan N. Duncan

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  1. Transport pathways for Asian combustion outflow over the Pacific:Interannual and seasonal variations Hongyu Liu, Daniel J. Jacob, Isabelle Bey, Robert M. Yantosca, Bryan N. Duncan Atmospheric Chemistry Modeling Group, Harvard University and Glen W. Sachse NASA Langley Research Center Draft to be posted soon!

  2. Objectives • Diagnose major pathways and source contributions for Asian outflow during TRACE-P • Place TRACE-P in an interannual and seasonal context

  3. Approach • Use GEOS-CHEM global 3-D simulation of tagged CO tracers for • Feb-Apr 2001: TRACE-P case studies • Feb-Apr 1994, 1998, 2000: interannual variability • Full year 1996: seasonal variability • Fossil fuel emissions for 1994 [Bey et al., 2001], climatological biomass burning [Duncan et al., 2001]. No interannual variability of emissions  to isolate the role of transport • OH monthly mean field from a full-chemistry simulation.

  4. Asian CO emissions (10-12 moles cm-2 s-1)

  5. Mixing of biomass burning pollution with industrial pollution in FRONTAL OUTFLOW TRACE-P DC-8 flight #7 (March 7, 2001) Asian anth. CO (600hPa) Asian BB CO (600hPa)

  6. Boundary layer outflow of Asian anthropogenic CO behind the cold front(950 hPa, 00 GMT March 9, 2001) DC-8 flight #8, P-3 flight #10

  7. European anthropogenic CO outflow (March 18, DC-8 flight #12) ppbv ppbv Mixed with Asian anth. CO European anth. CO (950hPa, 09GMT) Different scale ppbv

  8. Convective outflow of Asian biomass burning CO (March 26, DC-8 flight #15) 200 hPa, 21 GMT, March 26

  9. Eastward flux of Asian biomass burning CO emitted from different altitudes (topography) 0-250m 250-500m 500-1200m 500-1200m Asian BB CO sources are important contributions to frontal outflow in the lower FT! 0-500m Asian BB CO sources (low latitude)  convective outflow (need to be normalized by the total emissions at each elevation intervals) Latitude-altitude cross-sections of BB CO zonal flux over W Pacific

  10. 1998 (El Nino) Weak convection over SE Asia, fewer cold fronts 1994 (neutral) PEM-West B 2001 (La Nina) Strong convection over SE Asia, frequent cold fronts, strong PBL outflow 2000 (La Nina)

  11. Contributions from different sources to the Asian outflow of CO over the Pacific as a function of season in 1996 Asian fossil fuel Total / 5 European FF N American FF Asian BB African biomass burning

  12. Preliminary Conclusions • Transport pathways for Asian combustion outflow during TRACE-P • Asian anthropogenic and biomass burning emissions are mixed in frontal outflow • Convection is more important than fronts in lifting Asian biomass burning emissions to the free troposphere; • High-altitude sources make disproportionately large contributions to the Asian outflow maximum in the lower free troposphere; • No distinct European or African source signatures were observed (at least for CO); signal is weak and superimposed on that of Asian sources • Interannual variability of Asian outflow • Spring 2001: cold phase of ENSO • Frequent cold fronts, unusually strong outflow • Strong convection over SE Asia • Spring 1994 (PEM-West B): neutral • Much weaker outflow than in 2001 • Spring 1998: warm phase of ENSO • Weak frontal activity, weak anthropogenic outflow, but strong biomass burning outflow in lower troposphere. • Seasonal variability of Asian CO outflow to Pacific • Peaks in Feb-Mar (strong circulation + biomass burning) • Minimum in Jul-Aug (factor of 3 less than in Feb-Mar) • Europe > N America for CO, but opposite for ozone!

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