HR: 09:45h
AN: A21B-08    [PDF]
TI: Constraints on the Sources of Tropospheric Ozone From $^{210}$Pb-$^{7}$Be-O$_{3}$ Correlations
AU: * Liu, H
EM: hyl@nianet.org
AF: Harvard University, Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: * Liu, H
EM: hyl@nianet.org
AF: National Institute of Aerospace, 144 Research Drive, Hampton, VA 23666 United States
AU: Jacob, D J
EM: djj@io.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences and Division of Engineering and Applied Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AU: Dibb, J E
EM: jack.dibb@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans and Space, 39 College Road, Durham, NH 03824 United States
AU: Fiore, A M
EM: afiore@post.harvard.edu
AF: Harvard University, Department of Earth and Planetary Sciences and Division of Engineering and Applied 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 and Division of Engineering and Applied Sciences, 29 Oxford Street, Cambridge, MA 02138 United States
AB: The $^{210}$Pb-$^{7}$Be-O$_{3}$ relationships observed in three aircraft missions over the western Pacific (PEM-West A and B, TRACE-P) are simulated with a global 3-D chemical tracer model (GEOS-CHEM) driven by assimilated meteorological observations. Results are interpreted in terms of the constraints that they offer on sources of tropospheric ozone (O$_{3}$). Aircraft observations of Asian outflow along the Asian coast show strong $^{210}$Pb-O$_{3}$ correlations in Sep-Oct (PEMWest A) but such correlations are only seen at low latitudes in Feb-Mar (PEM-West B and TRACE-P). Observations further downwind over the Pacific show stronger $^{210}$Pb-O$_{3}$ correlations in Feb-Mar than Sep-Oct. The model reproduces these results and attributes the seasonal contrast to strong O$_{3}$ production and vertical mixing in Sep-Oct, seasonal shift of convection from China in Sep-Oct to Southeast Asia in Feb-Mar, and slow but sustained net O$_{3}$ production in Asian outflow over the western Pacific in Feb-Mar. Seasonal biomass burning over Southeast Asia in Feb- Mar is also responsible for the positive $^{210}$Pb-O$_{3}$ correlations observed in the middle and upper troposphere at low latitudes near Asia and over the remote Pacific. The model reproduces the observed absence of $^{7}$Be-O$_{3}$ correlations over the western Pacific during Sep-Oct, implying strong convective and weak stratospheric influence on O$_{3}$. The model shows stronger $^{7}$Be-O$_{3}$ correlations than the observations during PEM-West B and TRACE-P, suggesting it does not underestimate the stratospheric source of O$_{3}$. We conclude that less than 20-30% of model O$_{3}$ in the mid-latitude middle troposphere originates from the stratosphere in spring.
UR: http://research.nianet.org/~hyl/publications/liu2003_pbbeo3.pdf
DE: 0345 Pollution--urban and regional (0305)
DE: 0365 Troposphere--composition and chemistry
DE: 0368 Troposphere--constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2003 Fall Meeting