HR: 0800h
AN: A11C-0613    [Abstracts]
TI: Optimal Estimation of the Surface Fluxes of Chloromethanes Using a 3-D Global Atmospheric Chemical Transport Model
AU: * Xiao, X
EM: xuexiao@mit.edu
AF: Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
AU: Prinn, R G
EM: rprinn@mit.edu
AF: Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, United States
AU: Weiss, R F
EM: rfweiss@ucsd.edu
AF: Scripps Institution of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, United States
AU: Simmonds, P G
EM: petergsimmonds@aol.com
AF: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, United Kingdom
AU: Fraser, P J
EM: paul.fraser@csiro.au
AF: Marine and Atmospheric Research, Commonwealth Scientific and Industrial Research Organization, 107-121 Station Street, Aspendale, Victoria, 3195, Australia
AB: The four chloromethanes - methyl chloride (CH₃Cl), dichloromethane (CH₂Cl₂), chloroform (CHCl₃), and carbon tetrachloride (CCl₄) are chlorine-containing gases contributing significantly to stratospheric ozone depletion and/or having adverse health effects. Large uncertainties in estimates of their source and sink magnitudes and temporal and spatial variations currently exist. GEIA inventories and other bottom-up emission results are used to construct a priori maps of surface fluxes of these species. The Model of Atmospheric Transport and CHemistry (MATCH), driven by NCEP interannually varying meteorological fields, is then used to simulate the trace gas mole fractions using the a priori emissions and to quantify the time series for sensitivities of tracer concentrations to different aseasonal, seasonal, and regional sources and sinks. We then implement the Kalman filter (with the unit pulse response method) to estimate time-varying surface fluxes at a monthly resolution for the three short-lived species between 2000-2004, and at a 3-month resolution for CCl₄ between 1996-2004. The high frequency observations from AGAGE, SOGE, NIES and NOAA/GMD/ESRL HATS CATS and other low frequency flask observations from NOAA/GMD/ESRL HATS are used to constrain the source and sink magnitudes estimated as multiplying factors for the a priori emissions and contained in the state vector in the Kalman filter. The CH₃Cl inversion results indicate large CH₃Cl emissions of ~ 2278 Gg/yr from the tropical plants. Relative to their a priori magnitudes, the inversion nearly doubles global fungal emissions, slightly increases emissions from biomass burning and salt marshes, and reduces the global ocean source and soil sink. The inversion also implies greater seasonal oscillations of the natural sources and sink of CH₃Cl compared to the a priori. These results and those for the CH₂Cl₂, CHCl₃ and CCl₄ inversions will be presented and discussed.
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere: composition and chemistry
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting