Galanter, M., H.
Levy II, and G. R. Carmichael, 2000: Impacts of biomass burning
on tropospheric CO, NOX, and O3.
Journal of Geophysical Research, 105(D5), 6633-6653. |
Abstract: This study utilizes the National
Oceanic and Atmospheric Administration Geophysical Fluid Dynamics
Laboratory three-dimensional global chemical transport model to quantify
the impacts of biomass burning on tropospheric concentrations of carbon
monoxide (CO), nitrogen oxides (NOx),
and ozone (O3). We
construct updated global sources that emit 748 Tg CO/yr and 7.8 Tg N/yr
in the surface layer. Both sources include six types of
biomass: forest, savanna, fuelwood, agricultural residues,
domestic crop residues (burned in the home for cooking and/or heating),
and dried animal waste. Timing for the burning of forest, savanna,
and agricultural residues is based upon regional cultural use of fire,
vegetation type, local climate, and information gathered from satellite
observations, while emissions from the burning of fuelwood, domestic
crop residues, and dried animal waste are constant throughout the
year. Based on agreement with observations, particularly of CO, we
conclude that the collective uncertainty in our biomass burning sources
is much less than the factor of two suggested by previous estimates of
biomass burned in the tropics annually. Overall, biomass burning
is a major source of CO and NOx
in the northern high latitudes during the summer and fall and in the
tropics throughout most of the year. While it contributes more
than 50% of both the NOx and CO
in the boundary layer over major source regions, it has a much larger
global impact on the CO distribution in comparison to either NOx
or O3, contributing 15 to 30% of
the entire tropospheric CO background. The only significant
biomass burning contribution to NOx
at 500 mbar, due to the short lifetime of NOx
in the lower troposphere, is a plume occurring July through October in
the Southern Hemisphere subtropical free troposphere, stretching from
South America to the western Pacific. The largest impacts on O3
are limited to those regions where NOx
impacts are large as well. Near the surface, biomass burning
indirectly contributes less than half of the total O3
concentrations over major tropical source regions, up to 15% throughout
the year in the tropics, and 10 to 20% throughout the Southern
Hemisphere during September through November. At 500 mbar, the
largest contribution to O3
(20-30%) is correlated with the NOx
plume during July through November. Biomass burning contributes
less than 15% of either NOx or O3
in the upper troposphere. |