Status: this preprint was under review for the journal ACP but the revision was not accepted.
Estimation of lifetime of carbonaceous aerosol from open crop residue burning during Mount Tai Experiment 2006 (MTX2006)
X. L. Pan,Y. Kanaya,Z. F. Wang,Y. Komazaki,F. Taketani,H. Akimoto,P. Pochanart,and Y. Liu
Abstract. Studying the emission ratios of carbonaceous aerosols (element carbon, EC, and organic carbon, OC) from open biomass burning helps to reduce uncertainties in emission inventories and provides necessary constraints for model simulations. We measured apparent elemental carbon (ECa) and OC concentrations at the summit of Mount Tai (Mt. Tai) during intensive open crop residue burning (OCRB) episodes using a Sunset OCEC analyzer. Equivalent black carbon (BCe) concentrations were determined using a Multiple Angle Absorption Photometer (MAAP). In the fine particle mode, OC and EC showed strong correlations (r > 0.9) with carbon monoxide (CO). Footprint analysis using the FLEXPART_WRF model indicated that OCRB in central east China (CEC) had a significant influence on ambient carbonaceous aerosol loadings at the summit of Mt. Tai. ΔECa/ΔCO ratios resulting from OCRB plumes were 14.3 ± 1.0 ng m−3 ppbv−1 at Mt. Tai. This ratio was more than three times those resulting from urban pollution in CEC, demonstrating that significant concentrations of soot particles were released from OCRB. ΔOC/ΔCO ratio from fresh OCRB plumes was found to be 41.9 ± 2.6 ng m−3 ppbv−1 in PM1. The transport time of smoke particles was estimated using the FLEXPART_WRF tracer model by releasing inert particles from the ground layer inside geographical regions where large numbers of hotspots were detected by a MODIS satellite sensor. Fitting regressions using the e-folding exponential function indicated that the removal efficiency of OC (normalized to CO) was much larger than that of ECa mass, with mean lifetimes of 27 h (1.1 days) for OC and 105 h (4.3 days) for ECa, respectively. The lifetime of black carbon estimated for the OCRB events in east China was comparably lower than the values normally adopted in the transport models. Short lifetime of organic carbon highlighted the vulnerability of OC to cloud scavenging in the presence of water-soluble organic species from biomass combustion.
Received: 01 May 2012 – Discussion started: 07 Jun 2012
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Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institutes of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
Y. Kanaya
Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
Z. F. Wang
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institutes of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
Y. Komazaki
Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
F. Taketani
Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Japan
H. Akimoto
Acid Depositions and Oxidant Research Center, Asia Center for Air Pollution Research, Japan
P. Pochanart
School of Social and Environmental Development, National Institute of Development Administration, Bangkok, Thailand
Y. Liu
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institutes of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China
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