HR: 1330h
AN: A52B-0796    [PDF]
TI: Constraints on Asian and European Sources of Methane from CH4 - C2H6 - CO Correlations in Asian Outflow
AU: * Xiao, Y
EM: xyp@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Jacob, D J
EM: djj@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Wang, J
EM: jsw@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Palmer, P I
EM: pip@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Suntharalingam, P
EM: pns@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Yantosca, R M
EM: bmy@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Sachse, G W
EM: g.w.sachse@larc.nasa.gov
AF: NASA, NASA Langley Research Center, Hampton, VA 23681 United States
AU: Blake, D R
EM: dblake@orion.oac.uci.edu
AF: University of California, Irvine, Department of Chemistry, Irvine, CA 92697 United States
AU: Streets, D G
EM: dstreets@anl.gov
AF: Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 United States
AB: Aircraft observations in Asian outflow from the TRACE-P aircraft mission (March-April 2001) show persistently strong CH$_{4}$/C$_{2}$H$_{6}$ correlations with uniform slope (r2=0.8-0.95, slope=45-59 mol/mol for individual flights) and more variable CH$_{4}$/CO correlations (r2=0.6-0.88, slope=0.4-1.2 mol/mol). We apply a global 3-D simulation of the CH$_{4}$-C$_{2}$H$_{6}$-CO system, including consistent representations of sources and sinks for all three species, to interpret these correlations and the CH$_{4}$ concentration enhancements observed in TRACE-P toward improved estimates of Asian and European CH$_{4}$ sources. We use as a priori a state-of-the-science global CH$_{4}$ inventory constrained with NOAA/CMDL observations [J.S. Wang et al., J. Geophys. Res. 2003]. This inventory is found to overestimate CH$_{4}$ concentration enhancements in the Asian outflow while giving an unbiased simulation of CH$_{4}$-C$_{2}$H$_{6}$-CO correlations. Matching the TRACE-P observations in subtropical outflow requires a 70% decrease in seasonal Southeast Asian biomass burning emissions for CH$_{4}$, C$_{2}$H$_{6}$ and CO, implying a general overestimate of biomass burned. Matching the observations in the Asian outflow north of $30\deg$N can be achieved by using the Streets et al. [J. Geophys. Res., 2003] inventory for anthropogenic Asian emissions and by reducing the European and Russian sources by 25%. The former change increases the CH$_{4}$/C$_{2}$H$_{6}$ and CH$_{4}$/CO slopes, while the latter decreases the slopes, and the combination of the two changes maintains the unbiased simulation of the observed slopes. The resulting simulation also provides a good match to the observed CH$_{4}$ background and to the NOAA/CMDL data.
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting