Effect of fuel composition on combustion efficiency and emission factors for African savanna ecosystems

Ward, Darold E.; Hao, Wei Min; Susott, Ronald A.; Babbitt, Ronald E.; Shea, Ronald W.; Kauffman, J. Boone; Justice, Chris

doi:10.1029/95jd02595

Cited by 202 publications

(207 citation statements)

References 16 publications

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“…Measurements made by Ward et al [1992Ward et al [ , 1996 in the regional haze generated by African savanna and Brazilian fires measured around 3% BC in smoldering fires and $15-20% in active flaming combustion with the exact aerosol makeup being highly dependent on the type of vegetation. However, we see that our measurements of BC in the burning season lie between these two fire regimes suggesting that the air sampled over the Darwin area contained a mix of fire plumes generated in both active and smoldering fires further inland as might be expected.…”

Section: Aerosol Compositionmentioning

confidence: 99%

Aerosol and trace‐gas measurements in the Darwin area during the wet season

Allen¹,

Vaughan²,

Bower³

et al. 2008

J. Geophys. Res.

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[1] The composition of the planetary boundary layer in regions of deep tropical convection has a profound impact on the Tropical Tropopause Layer (TTL). The Aerosol and Chemical Transport in tropIcal conVEction (ACTIVE) aircraft campaign was conducted from November 2005 to February 2006 from Darwin, Australia, to characterize the influence of both monsoonal and localized land-based deep convection on the composition of the TTL. This paper summarizes the composition of the potential inflow to such convection in terms of aerosol particle size and composition, carbon monoxide, and ozone, as measured in the lowest 4 km of the atmosphere by the NERC Dornier-228 aircraft during 28 flights in different meteorological regimes over the course of ACTIVE. Six contrasting periods are identified in the boundary layer background as a result of the prevailing meteorology and sources of pollution. The campaign began with a relatively polluted and variable biomass burning season in November, followed by a transition to the monsoon season through December with much less burning. A clean maritime flow dominated the wet-active, and dry-inactive, monsoon period in January; it was followed by a monsoon break period in February, with a return to continental flow and a more premonsoon background state. Deep convective systems, capable of transporting boundary layer air to the TTL, were observed daily outside of the monsoon periods. The chemical composition of submicron aerosols in the premonsoon periods was dominated by a mix of fresh and aged organic material with significant black carbon, well-correlated with carbon monoxide indicating a common burning source, while marine aerosol during the monsoon changed markedly between the wet and dry phases. High concentrations of coarse-mode aerosols were also observed in the monsoon: the clean, marine air masses and high surface winds imply that sea salt may be the dominant aerosol type under these conditions. The climatology presented here will provide a valuable data set for model simulation of chemical and aerosol transport by deep convection in the Darwin region.Citation: Allen, G., et al. (2008), Aerosol and trace-gas measurements in the Darwin area during the wet season,

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Section: Aerosol Compositionmentioning

confidence: 99%

Aerosol and trace‐gas measurements in the Darwin area during the wet season

Allen¹,

Vaughan²,

Bower³

et al. 2008

J. Geophys. Res.

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“…Published emission factors for CO 2 are 1393 -1620 gm pollutant/kg biofuel with carbon content ranging from 41.8-50% Zhang et al, 2000;Brocard et al, 1998;Smith et al, 1993;; if we adopt a 50% carbon content, the emission factor range is reduced to 1551-1664 gm CO 2 /kg biofuel. The distribution of carbon in the products from biomass burning: CO 2 , CO, CH 4 , NMHC, TSP, ash, and uncombusted fuel, is strongly influenced by the temporal pattern of flaming and smoldering (more and less efficient combustion, respectively) in the burning process [Brocard et al, 1998;Jenkins and Turn, 1994;Ward et al, 1996;Joshi et al, 1989].…”

Section: Appendix C: Emission Factorsmentioning

confidence: 99%

“…[143] The emission factors of trace gases from biomass combustion are influenced by several factors including the actual amount of carbon in the preburned dry matter, the size, shape and moisture content of the sample, and the flaming versus smoldering pattern of the burning process [Ward et al, 1996]. Most published emission factors are based on emission ratios using a carbon balance method which requires knowing the carbon content of the fuel.…”

Section: Appendix C: Emission Factorsmentioning

confidence: 99%

An assessment of biofuel use and burning of agricultural waste in the developing world

Yevich

Logan

2003

Global Biogeochemical Cycles

626

572

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[1] We present an assessment of biofuel use and agricultural field burning in the developing world. We used information from government statistics, energy assessments from the World Bank, and many technical reports, as well as from discussions with experts in agronomy, forestry, and agro-industries. We estimate that 2060 Tg biomass fuel was used in the developing world in 1985; of this, 66% was burned in Asia, and 21% and 13% in Africa and Latin America, respectively. Agricultural waste supplies about 33% of total biofuel use, providing 39%, 29%, and 13% of biofuel use in Asia, Latin America, and Africa, and 41% and 51% of the biofuel use in India and China. We find that 400 Tg of crop residues are burned in the fields, with the fraction of available residue burned in 1985 ranging from 1% in China, 16-30% in the Middle East and India, to about 70% in Indonesia; in Africa about 1% residue is burned in the fields of the northern drylands, but up to 50% in the humid tropics. We distributed this biomass burning on a spatial grid with resolution of 1°Â 1°, and applied emission factors to the amount of dry matter burned to give maps of trace gas emissions in the developing world. The emissions of CO from biofuel use in the developing world, 156 Tg, are about 50% of the estimated global CO emissions from fossil fuel use and industry. The emission of 0.9 Pg C (as CO 2 ) from burning of biofuels and field residues together is small, but nonnegligible when compared with the emissions of CO 2 from fossil fuel use and industry, 5.3 Pg C. The biomass burning source of 10 Tg/yr for CH 4 and 2.2 Tg N/yr of NO x are relatively small when compared with total CH 4 and NO x sources; this source of NO x may be important on a regional basis.

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“…We focused on CO, CH 4 , and CO 2 . However, since the Modified Combustion Efficiency (MCE, defined as the amount of C released as CO 2 divided by the amount of C released as CO 2 plus CO ) has been used as an effective predictor for the emission of smoke gas composition from biomass fires (e.g., Ward et al, 1996;Sinha et al, 2003;Yokelson et al, 2003) and for certain aerosol species and characteristics (e.g., McMeeking et al, 2009;Janhäll et al, 2010), our findings on CO and CO 2 EFs can be used to better understand emissions of other trace gases and aerosols as well. We restricted our analysis to in situ measurements due to the focus on spatio-temporal variability as a result of variability in vegetation and climatic conditions; laboratory measurements of EFs were not taken into account.…”

Section: T T Van Leeuwen and G R Van Der Werf: Spatio-temporal Vamentioning

confidence: 99%

Spatial and temporal variability in the ratio of trace gases emitted from biomass burning

Leeuwen¹,

Werf²

2011

Atmos. Chem. Phys.

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Abstract. Fires are a major source of trace gases and aerosols to the atmosphere. The amount of biomass burned is becoming better known, most importantly due to improved burned area datasets and a better representation of fuel consumption. The spatial and temporal variability in the partitioning of biomass burned into emitted trace gases and aerosols, however, has received relatively little attention. To convert estimates of biomass burned to trace gas and aerosol emissions, most studies have used emission ratios (or emission factors (EFs)) based on the arithmetic mean of field measurement outcomes, stratified by biome. However, EFs vary substantially in time and space, even within a single biome. In addition, it is unknown whether the available field measurement locations provide a representative sample for the various biomes. Here we used the available body of EF literature in combination with satellite-derived information on vegetation characteristics and climatic conditions to better understand the spatio-temporal variability in EFs. While focusing on CO, CH 4 , and CO 2 , our findings are also applicable to other trace gases and aerosols. We explored relations between EFs and different measurements of environmental variables that may correlate with part of the variability in EFs (tree cover density, vegetation greenness, temperature, precipitation, and the length of the dry season). Although reasonable correlations were found for specific case studies, correlations based on the full suite of available measurements were lower and explained about 33%, 38%, 19%, and 34% of the variability for respectively CO, CH 4 , CO 2 , and the Modified Combustion Efficiency (MCE). This may be partly due to uncertainties in the environmental variables, differences in measurement techniques for EFs, assumptions on the ratio between flaming and smoldering combustion, and incomplete information on the location and timing of EF Correspondence to: T. T. van Leeuwen (thijs.van.leeuwen@falw.vu.nl) measurements. We derived new mean EFs, using the relative importance of each measurement location with regard to fire emissions. These weighted averages were relatively similar to the arithmetic mean. When using relations between the environmental variables and EFs to extrapolate to regional and global scales, we found substantial differences, with for savannas 13% and 22% higher CO and CH 4 EFs than the arithmetic mean of the field studies, possibly linked to an underrepresentation of woodland fires in EF measurement locations. We argue that from a global modeling perspective, future measurement campaigns could be more beneficial if measurements are made over the full fire season, and if relations between ambient conditions and EFs receive more attention.

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Effect of fuel composition on combustion efficiency and emission factors for African savanna ecosystems

Cited by 202 publications

References 16 publications

Aerosol and trace‐gas measurements in the Darwin area during the wet season

Aerosol and trace‐gas measurements in the Darwin area during the wet season

An assessment of biofuel use and burning of agricultural waste in the developing world

Spatial and temporal variability in the ratio of trace gases emitted from biomass burning

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