The Impact of Uncertainties in African Biomass Burning Emission Estimates on Modeling Global Air Quality, Long Range Transport and Tropospheric Chemical Lifetimes

Atmosphere

Jason E. Williams¹  Michiel van Weele¹  Peter F. J. van Velthoven¹  Marinus P. Scheele¹  Catherine Liousse² 

[1]Chemistry and Climate Division, Royal Netherlands Institute (KNMI), P.O. Box 201, De Bilt 3730 AE, The Netherlands

[2]Laboratoire d’Aerologie, UMR 5560, 31400 Toulouse, France

关键词: African biomass burning;    emission inventories;    long range transport;    air quality;    methane lifetimes;   

DOI  :  10.3390/atmos3010132

来源: mdpi

【 摘 要 】

The chemical composition of the troposphere in the tropics and Southern Hemisphere (SH) is significantly influenced by gaseous emissions released from African biomass burning (BB). Here we investigate how various emission estimates given in bottom-up BB inventories (GFEDv2, GFEDv3, AMMABB) affect simulations of global tropospheric composition using the TM4 chemistry transport model. The application of various model parameterizations for introducing such emissions is also investigated. There are perturbations in near-surface ozone (O₃) and carbon monoxide (CO) of ~60–90% in the tropics and ~5–10% in the SH between different inventories. Increasing the update frequency of the temporal distribution to eight days generally results in decreases of between ~5 and 10% in near-surface mixing ratios throughout the tropics, which is larger than the influence of increasing the injection heights at which BB emissions are introduced. There are also associated differences in the long range transport of pollutants throughout the SH, where the composition of the free troposphere in the SH is sensitive to the chosen BB inventory. Analysis of the chemical budget terms reveals that the influence of increasing the tropospheric CO burden due to BB on oxidative capacity of the troposphere is mitigated by the associated increase in NO_x emissions (and thus O₃) with the variations in the CO/N ratio between inventories being low. For all inventories there is a decrease in the tropospheric chemical lifetime of methane of between 0.4 and 0.8% regardless of the CO emitted from African BB. This has implications for assessing the effect of inter-annual variability in BB on the annual growth rate of methane.

【 授权许可】

CC BY   
© 2012 by the authors; licensee MDPI, Basel, Switzerland.