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Published August 12, 2009 | Published
Journal Article Open

Emissions from biomass burning in the Yucatan

Abstract

In March 2006 two instrumented aircraft made the first detailed field measurements of biomass burning (BB) emissions in the Northern Hemisphere tropics as part of the MILAGRO project. The aircraft were the National Center for Atmospheric Research C-130 and a University of Montana/US Forest Service Twin Otter. The initial emissions of up to 49 trace gas or particle species were measured from 20 deforestation and crop residue fires on the Yucatan peninsula. This included two trace gases useful as indicators of BB (HCN and acetonitrile) and several rarely, or never before, measured species: OH, peroxyacetic acid, propanoic acid, hydrogen peroxide, methane sulfonic acid, and sulfuric acid. Crop residue fires emitted more organic acids and ammonia than deforestation fires, but the emissions from the main fire types were otherwise fairly similar. The Yucatan fires emitted unusually high amounts of SO2 and particle chloride, likely due to a strong marine influence on this peninsula. As smoke from one fire aged, the ratio ΔO3/ΔCO increased to ~15% in <~1 h similar to the fast net production of O_3 in BB plumes observed earlier in Africa. The rapid change in O_3 occurs at a finer spatial scale than is employed in global models and is also faster than predicted by micro-scale models. Fast increases in PAN, H_2O_2, and two organic acids were also observed. The amount of secondary organic acid is larger than the amount of known precursors. Rapid secondary formation of organic and inorganic aerosol was observed with the ratio ΔPM2.5/ΔCO more than doubling in ~1.4±0.7 h. The OH measurements revealed high initial levels (>1×10^7 molecules/cm^3) that were likely caused in part by high initial HONO (~10% of NO_y). Thus, more research is needed to understand critical post emission processes for the second-largest trace gas source on Earth. It is estimated that ~44 Tg of biomass burned in the Yucatan in the spring of 2006. Mexican BB (including Yucatan BB) and urban emissions from the Mexico City area can both influence the March-May air quality in much of Mexico and the US.

Additional Information

© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License. Received: 2 October 2008 – Published in Atmos. Chem. Phys. Discuss.: 9 January 2009. Revised: 30 June 2009 – Accepted: 28 July 2009 – Published: 12 August 2009. The authors thank Eric Hintsa and Anne-Marie Schmoltner of NSF for supplemental funding for ASU and U Miami, and travel funds for CU to conduct measurements on the Twin Otter. We thank the Twin Otter and C-130 pilots. Thanks go to Sasha Madronich, Luisa Molina, and Jose Meitin for coordinating the overall MILAGRO campaign. The University of Montana and the Twin Otter were supported mostly by NSF grant ATM-0513055. Yokelson was also supported by the Strategic Environmental Research and Development Program (SERDP) of DoD. Support for the USFS and Twin Otter was provided by the NASA North American Carbon Plan (NNHO5AA86I). P. F. DeCarlo and J. L. Jimenez were supported by NSF ATM-0513116 and ATM-0449815, NASA NNG06GB03G, and EPA Graduate Fellowship FP-91650801. Participation by Arizona State University was supported by NSF grant ATM-0531926. We gratefully acknowledge the use of TEMs within the LeRoy Eyring Center for Solid State Science at Arizona State University. Support to the University of Miami was provided by NSF (ATM 0511820). X. Zhu and L. Pope provided excellent technical support for the canister trace gas analyses. Support for operation of the Caltech CIMS instrument was provided by NASA (NNG04GA59G) and by EPA-STAR support for J. Crounse. The C-130 forward looking video was provided by NCAR/EOL under sponsorship of the National Science Foundation. http://data.eol.ucar.edu/.

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August 22, 2023
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