Publications grouped by topic; abstracts below the list . (-) submitted; (*) in press. Numerous-author publications are on my CV but not listed here.

Emission inventories (past-present-future)
2007 Historical biofuel consumption Biofuel since 1850, considering drivers beyond population. (Fernandes, Trautmann, Streets, Roden, Bond)
2007 Historical BC/OC inventory Black & organic carbon since 1850, considering technology change. (Bond & lots of group members)
2004 Future BC/OC emissions Technology considerations. BC/OC plateau in the near future. (Streets, Bond, Lee and Jang)
2004 Global emission inventory of black & organic carbon Emissions of BC/OC from everywhere. Really long paper. Sorry. (Bond, Streets et al.)
2003 Asian emission inventories for TRACE-P Emissions of everything from Asia . (Streets, Bond et al.)
2001 Black carbon emissions in China. Technology-based emission inventory. (Streets, Gupta et al.)

Aerosol optical properties, especially absorption
2007 Brown carbon color Spectra of yellow and brown carbon (Sun, Biedermann, Bond)
2006 Coating limitations Probable range of absorption amplification by coated particles. (Bond, Habib & Bergstrom)
2006 Optics review Review of why light is absorbed by soot particles, and how much. Another long one. (Bond & Bergstrom) ** Inquire about Annotated Version
2001 Spectral dependence of light absorption by carbon particles Yellow and brown carbon, and hypotheses about causes. (Bond)

Policy discussions
2007 Why not black carbon? Reasons why aerosols don't end up in climate policy; reasons why those reasons aren't supportable (Bond)
2005 Can BC save us from global warming? Policy comment on black carbon/climate, including estimate of direct GWP. (Bond & Sun)
2004 Residential fuels and atmospheric chemistry Impact of solid fuels, including daring attempts at combined GWP. (Bond, Venkataraman & Masera)

Source characterization
(-) 2007 Lab & field cookstoves In-use cookstoves don't behave like lab stoves. Some improved stoves are better. 3 years of doing this stuff. (Roden, Bond & lots of others)
2006 ARACHNE in Honduras Emission factors and optical properties from real cooking fires. (Roden, Bond, Conway & Osorto)
2006 Oil & gas boiler Optical properties, size distributions, etc. Net effect of technology switch.(Bond, Wehner et al.)
2002 Primary particle emissions from residential coal burning Optics & size distribution of chunk coal burning. (Bond, Covert et al.)
1999 Light absorption by particles from a lignite plant. Lignite stoker boiler. Very little absorption. (Bond, Wehner et al.)
1999 Climate-relevant emissions from a lignite plant. Size distributions from stoker boiler. (Wehner, Bond et al.)
1998 Quantifying emissions of light absorption: Measure light absorption at the source. (Bond, Charlson and Heintzenberg)

Analytical techniques (again, mostly absorption & "elemental" carbon)
(-) 2008 Physical basis of thermal-optical analysis Express the whole mess as a matrix reactor equation. How to live with an underdetermined system. (Boparai, Lee & Bond)
(-) 2007 Charring in thermal-optical analysis Why does organic material pyrolyze? Looks like oxygenated polymers. (Subramanian, Boparai, Chen, Bond)
2007 Beads on fiber filters Absorbing liquid particles on filter samples alter absorption. (Subramanian, Roden, Boparai, Bond)
1999 Calibration of light absorption measurements: The infamous PSAP calibration paper. (Bond, Anderson and Campbell)

Climate modeling
2007 Future forcing Future climate forcing by individual source sectors. (Koch, Bond, Streets, Unger)
2007 Forcing by individual sectors Present-day climate forcing by individual source sectors. (Koch, Bond et al.)

Less-formal presentations and writeups: Access by clicking on the links.
Simple derivation & revision of Mark Jacobson's diesel-gasoline comparison (130k pdf, 2003)
Climate forcing by black and organic carbon: central values and uncertainties: 900k pdf (Bond, Rasch, Collins, Streets at AGU 2002, San Francisco)
Chemical & optical properties of chunk coal emissions: 300k pdf (Bond, Quinn, Bates at IAC 2002, Taipei)

Revisiting thermal-optical analyses of carbonaceous aerosol using a physical model
Poonam Boparai, Jongmin Lee, and Tami C. Bond
Submitted to Aerosol Science and Technology, January 2008

Thermal-optical analysis has been widely used to separate both ambient and source samples into two components, organic and elemental carbon. During this process, pyrolytic carbon is formed. We examine aerosol samples from hexane combustion, diesel exhaust, flaming and smoldering wood combustion, and pipetted samples of fulvic and humic acid, and confirm several observations that have previously appeared in the literature: (1) Pyrolytic carbon and light-absorbing carbon (LAC) are released at similar temperatures; (2) Organic carbon can be retained on the filter even after high temperatures under inert gas; (3) Potassium chloride causes early oxidation of LAC. These facts imply that analysis procedures must account for co-evolution of different kinds of carbon, and we present a method for re-interpreting existing TOA results which does so. We also observe that absorption per carbon depends on filter transmission for LAC but not for pyrolytic carbon, and confirm that optical properties of pyrolytic carbon and LAC are greatly different. Our model, REACTO (REAnalyzing Carbon Traces Optically) exploits the differences in optical properties to separate these carbon types during each analysis phase.

Inferences about atmospheric organic aerosol composition using charring in thermal-optical analysis
R. Subramanian, Poonam Boparai, Yanju Chen, and Tami C. Bond
Submitted to Environmental Science and Technology, December 2007

Laboratory and field investigations of particulate and carbon monoxide emissions from traditional and improved cookstoves
Christoph A. Roden, Tami C. Bond, Stuart Conway, Anibal Benjamin Osorto Pinel, Nordica MacCarty, and Dean Still
Submitted to Atmospheric Environment, December 2007

Historical Emissions of Black and Organic Carbon Aerosol from Energy-Related Combustion, 1850-2000
Tami C. Bond, Ekta Bhardwaj, Rong Dong, Rahil Jogani, Soonkyu Jung, Christoph Roden, David G. Streets, Nina M. Trautmann
Global Biogeochemical Cycles 21, GB2018, doi:10.1029/2006GB002840, 2007

Global Biofuel Use, 1850-2000
Suneeta D. Fernandes, Nina M. Trautmann, David G. Streets, Christoph A. Roden and Tami C. Bond
Global Biogeochemical Cycles 21, GB2019, doi:10.1029/2006GB002836

This paper presents annual, country-level estimates of biofuel use for the period 1850-2000. We estimate that global biofuel consumption rose from about 1000 Tg in 1850 to 2460 Tg in 2000, an increase of 140%. In the late 19th century, biofuel consumption in North America was very high, ~220-250 Tg/yr, because widespread land clearing supplied plentiful fuelwood. At that time biofuel use in Western Europe was lower, ~180-200 Tg/yr. As fossil fuels became available, biofuel use in the developed world fell. Compensating changes in the regional patterns of biofuel use caused global consumption to remain remarkably stable between 1850 and 1950 at ~1200 ±200 Tg/yr. It was only after World War II that biofuel use began to increase more rapidly in response to population growth in the developing world. Between 1950 and 2000, biofuel use in Africa, South Asia, and Southeast Asia grew by 170%, 160%, and 130%, respectively.

Yellow Beads and Missing Particles: Trouble Ahead for Filter-Based Absorption Measurements
R. Subramanian, Christoph A. Roden, Poonam Boparai and Tami C. Bond
Aerosol Science and Technology 41, 630-637, 2007

Particulate emissions from low-temperature biomass burning are dominated by organic matter. Here, we show that such particles have a liquid, bead-like appearance when collected on fibrous filters, and their numbers are far less than expected for solid spherical particles. These shapes are in line with published drop-on-fiber theories for liquids entrained on filaments. A smoldering pine sample is yellowish and chars substantially in thermal-optical analysis (TOA), indicating that such liquid particles could affect both TOA and absorption measurements of such samples. Similar colored samples collected in the field from burning of rice-straw and cook stove emissions also show a similar liquid appearance.

Linking future aerosol radiative forcing to shifts in source activities
Dorothy Koch, Tami C. Bond, David Streets, and Nadine Unger
Geophysical Research Letters, 34, L05821, doi:10.1029/2006GL028360.

We model future direct radiative forcings of the major anthropogenic aerosol species, sulfate, black and organic carbon, within industrial, power, transport, and residential sectors and biomass burning. A sectoral perspective helps to inform mitigation directions. More accurate projections are facilitated by recent carbonaceous aerosol emission estimates that incorporate projected technology changes, now available for the Intergovernmental Panel on Climate Change scenarios A1B and B1, for 2030 and 2050. Net present-day model anthropogenic forcing is-0.11Wm2. By 2050 this doubles (A1B) or drops by 30% (B1), depending mostly on sulfate changes in the industry and power sectors. Present-day (nonbiomass burning) BC forcing comes mostly from residential sources (+0.09Wm2), however this is projected to decrease by more than a factor of 10 by 2050. Future BC forcing is projected to come mostly from transport, changing from +0.06 W m2 in 2000 to +0.04 (B1) or +0.07 W m2 (A1B) by 2050.

Global Impacts of Aerosols from Particular Source Sectors and Regions
Dorothy Koch, Tami C. Bond, David Streets, Nadine Unger, and Guido R. van der Werf
Journal of Geophysical Research, 112, D02205, doi:10.1029/2005JD007024.

We study the impacts of present-day aerosols emitted from particular regions and from particular sectors, as predicted by the Goddard Institute for Space Studies GCM. We track the distribution and direct radiative forcing of aerosols, including sulfate and black and organic carbon, emitted from major source regions (North America, Europe, south Asia, Southeast Asia, South America, and Africa). We also partition the emissions by sector, including industrial, power, residential, transport, biomass burning, and natural. Southeast Asia produces 15% and 10% of the world’s black carbon and sulfate and exports over 2/3 of this burden over the Northern Hemisphere. About 1/2 of the SO2 emitted by Southeast Asia and Europe is not converted to sulfate because of oxidant limitation. Although Africa has the largest biomass burning emissions, South America generates a larger (about 20% of the global carbonaceous) aerosol burden; about 1/2 of this burden is exported and dominates the carbonaceous aerosol load in the Southern Hemisphere. Calculated direct anthropogenic radiative forcings are -0.29, -0.06, and 0.24 Wm-2 for sulfate, organic, and black carbon, respectively. The largest BC radiative forcings are from residential (0.09 W m-2) and transport (0.06 Wm-2) sectors, making these potential targets to counter global warming. However, scattering components within these sectors reduce these to 0.04 and 0.03 Wm-2, respectively. Most anthropogenic sulfate comes from power and industry sectors, and these sectors are responsible for the large negative aerosol forcings over the central Northern Hemisphere.

Limitations in the Enhancement of Visible Light Absorption due to Mixing State
T. C. Bond, G. Habib, and R. W. Bergstrom
Journal of Geophysical Research 111, D20211, doi:10.1029/2006JD007315, 2006

Absorption by light absorbing carbon (LAC) particles increases when the carbon is mixed with other material, and this change affects climate forcing. We investigate this increase theoretically over a realistic range of particle sizes. Perfect mixing at the molecular level often overestimates absorption. Assuming that LAC is coated by a concentric shell of weakly-absorbing material, we calculate absorption by a range of realistic particle sizes and identify regimes in which absorption behaves similarly. We provide fits to amplification in five regions: (1) small cores and (2) intermediate cores, both with large shells; (3) small to intermediate cores with intermediate shells; (4) cores with growing shells; and (5) intermediate to large cores with large shells. Amplification in region 1 is highest but physically implausible. Amplification in region 5 is constant at about 1.9 and represents an asymptote for particles with broad size distributions. Because absorption by aggregates is amplified by about 1.3 above spherical particles, and that factor is lost when particles are coated, we suggest that absorption by aged aerosol is about 1.5 times greater than that of fresh aerosol. The rate at which particles acquire sufficient coating to increase their original diameter by 60% is important in determining total absorption during their atmospheric lifetimes. Fitted amplification factors are not very sensitive to assumed refractive index of LAC, and can be used even in simple models.

Emission Factors and Real-time Optical Properties of Particles Emitted from Traditional Wood Burning Cookstoves
C. Roden, T. C. Bond, S. Conway, and A. B. Osorto Pinel
Environmental Science and Technology 40, 6750-6757, 2006

It is estimated that the combustion of biofuel generates 20% of all carbonaceous aerosols, yet little is known about the properties of these particles.  We designed and built a portable, battery-operated emission sampling cart to measure real-time optical properties and other emission characteristics of biofuel cookstoves in Honduras.  We found average particulate emission factors of 10g/kg, much higher than emission factors found in previous laboratory studies.  During strongly flaming events, we observed very dark particles with low instantaneous single scatter albedos. Elemental carbon to total carbon ratios ranged from 0.07 to 0.64, confirming that high elemental carbon fractions can be emitted from biofuel combustion.  Absorption Ångstrom exponents, representing the dependence of absorption on wavelength, ranged from 1 to 5. Strongly-absorbing particles with absorption inversely dependent on wavelength were emitted separately from weakly-absorbing particles with strong wavelength dependence of absorption.  These distinct phases exhibited during combustion suggest that carbonaceous aerosols from biofuel combustion are externally mixed at emission.

Climate-Relevant Properties of Primary Particulate Emissions from Oil and Natural Gas Combustion
T. C. Bond, B. Wehner, A. Plewka, A. Wiedensohler, J. Heintzenberg, and R. J. Charlson
Atmospheric Environment, 40, 3574-3587, 2006

We report emissions of mass, light absorption, particle number, chemical composition and size-resolved organic species from an industrial boiler that burned natural gas and residual oil. Organic compounds detected from oil combustion are mainly alkanes; it is not a major source of identifiable polyaromatic hydrocarbons. Elemental carbon and organic carbon make up approximately 38% and 15% of the particles from oil burning, respectively. Mass emissions from natural gas were below detection limits. A number peak of ultrafine aerosol (diameters lower than 10 nm) was always associated with oil burning. Burning at full power produced the greatest number of particles in the accumulation mode. Natural gas also produced fine particles, but at a much lower rate. The emission rate of light-absorbing particles from this relatively new boiler is lower than that in current emission inventories. However, real-time measurements show a large contribution to emitted light absorption from boiler warm-up and transients, even those with very short durations. The measured absorption is best explained with a constant absorption cross-section for EC, rather than predictions based on size distribution or mixed aerosol; this finding is consistent with EC in fractal-aggregate form. We compare the emissions with those of a lignite stoker, which this boiler replaced during environmental cleanup in the mid-1990s. Emissions of mass, light absorption and particles are lowest from natural gas, but the oil boiler is also a substantial improvement: emissions of particulate matter are 100 times lower, and emitted absorption is three times lower. However, the oil-burning emissions have a greater net warming effect per mass than those of the lignite plant.

Light Absorption by Carbonaceous Particles: An Investigative Review
T. C. Bond and R. W. Bergstrom
Aerosol Science and Technology, 40(1), 27-47, 2006

The optical properties of the light-absorbing, carbonaceous substance often called "soot", "black carbon", or "carbon black" have been the subject of some debate. These properties are necessary to model how aerosols affect climate, and our review is targeted specifically for that application. We recommend the term light-absorbing carbon to avoid conflict with operationally-based definitions. Absorptive properties depend on molecular form, particularly the size of sp2-bonded clusters. Freshly-generated particles should be represented as aggregates, and their absorption is like that of particles small relative to the wavelength. Previous compendia have yielded a wide range of values for both refractive indices and absorption cross section. The absorptive properties of light-absorbing carbon are not as variable as is commonly believed. Our tabulation suggests a mass-normalized absorption cross section of 7.5+/- 1.2 m2/g at 550 nm for uncoated particles. We recommend a narrow range of refractive indices for strongly-absorbing carbon particles, of which the highest is 1.95-0.79i. Our refractive indices are consistent with most measurements reported in the literature, and values used in present-day climate modeling are in error. Realistic refractive indices underpredict measured absorption by about 30% when used with common theories for spherical particles or aggregates. Field programs since about 1970 have measured quantities relevant to light absorption, but have only recently made enough measurements to isolate the light-absorbing carbonaceous component and determine its absorptive properties.

Minor errors introduced in production have been corrected in the Annotated Version, available from the authors.

Can Reducing Black Carbon Emissions Counteract Global Warming?
T. C. Bond and H. Sun
Environmental Science and Technology, 39, 5921-5926, 2005

Field measurements and model results have recently shown that aerosols may have important climatic impacts. One line of inquiry has investigated whether reducing climate-warming “soot” or “black carbon” aerosol emissions can form a viable component of mitigating global warming. We review and acknowledge scientific arguments against considering aerosols and greenhouse gases in a common framework, including the differences in the physical mechanisms of climate change and relevant time scales. We argue that such a joint consideration is consistent with the language of the United Nations Framework Convention on Climate Change. We synthesize results from published climate-modeling studies to obtain a global warming potential for black carbon relative to that of CO2 (680 on a 100-year basis). This calculation enables a discussion of cost-effectiveness for mitigating the largest sources of black carbon. We find that many emission reductions are either expensive or difficult to enact when compared with greenhouse gases, particularly in Annex I countries. Finally, we propose a role for black carbon in climate mitigation strategies that is consistent with the apparently conflicting arguments raised during our discussion. Addressing these emissions is a promising way to reduce climatic interference primarily for nations that have not yet agreed to address greenhouse gas emissions, and provides the potential for a parallel climate agreement.

On the Future of Carbonaceous Aerosol Emissions
D. G. Streets, T. C. Bond, T. Lee, and C. Jang
Journal of Geophysical Research, 109 (D24), doi:10.1029/2004JD004902, 2004

This paper presents the first model-based projections of future emissions of the primary carbonaceous aerosols, black carbon (BC) and organic carbon (OC). The projections build on a new 1996 inventory of present-day emissions that contains detailed fuel, technology, sector, and world-region specifications. The forecasts are driven by two IPCC scenarios, A1B and B1 out to 2030, incorporating not only changing patterns of fuel use but also technology development. Emissions from both energy generation and open biomass burning are included. We project that global BC emissions will decline by 5% under the IPCC A1B scenario by 2030 and by 30% under the B1 scenario. We project that OC emissions will decline by 16% under A1B and 29% under B1. The introduction of advanced technology with lower emission rates, as well as a shift away from the use of traditional solid fuels in the residential sector, more than offsets the increased combustion of fossil fuels worldwide. We estimate that there are additional reductions of 15-30% possible, if some other, more drastic measures could be implemented. Though emissions generally are expected to improve, in some parts of the world—particularly South America, Northern Africa, the Middle East, South Asia, Oceania, and Southeast Asia— we project increasing BC emissions under the A1B scenario. Particularly difficult to constrain are BC emissions from the transport sector, which are projected to increase under both scenarios. We expect that the global BC/OC emission ratio for energy sources will increase under both scenarios and for all sources under A1B; this signifies a net shift toward increased global warming.

Global Atmospheric Impacts of Residential Fuels
T. C. Bond, C. Venkataraman, and O. Masera
Energy for Sustainable Development VIII (3), 54-66, 2004

We discuss the contribution of residential fuels to atmospheric composition on very large scales. The impacts of increased pollutant concentration may affect the behavior of the Earth-atmosphere system. We discuss the various species that lead to these changes and examine emissions of air pollutants from residential fuels in relation to emissions from other sources. We also present modeled atmospheric concentrations and identify regions in which residential fuels contribute greatly to the atmospheric aerosol. Finally, we compare total emissions from a variety of residential end-use technologies, with the implication that improvements could lead to a cleaner atmosphere on scales that are much larger than typically considered.

A Technology-Based Global Inventory of Black and Organic Carbon Emissions from Combustion
T. C. Bond, D. G. Streets, K. F. Yarber, S. M. Nelson, J.-H. Woo, Z. Klimont
Journal of Geophysical Research, 109, D14203, doi:10.1029/2003JD003697, 2004.

We present a global tabulation of black carbon (BC) and primary organic carbon (OC) particles emitted from combustion. We include emissions from fossil fuels, biofuels, open biomass burning, and burning of urban waste. Previous “bottom-up” inventories of black and organic carbon have assigned emission factors based on fuel type and economic sector alone. Because emission rates are highly dependent on combustion practice, we consider combinations of fuel, combustion type, and emission controls, and their prevalence on a regional basis. Central estimates of global annual emissions are 8.0 Tg for black carbon and 33.9 Tg for organic carbon. These estimates are lower than previously-published estimates by 25 to 35%. The present inventory is based on 1996 fuel-use data, updating previous estimates that have relied on consumption data from 1984. An offset between decreased emission factors and increased energy use since the base year of the previous inventory prevents the difference between this work and previous inventories from being greater. The contributions of fossil fuel, biofuel, and open burning are estimated as 38%, 20%, and 42% respectively for BC, and 7%, 19%, and 74% respectively for OC. We present a bottom-up estimate of uncertainties in source strength by combining uncertainties in particulate matter emission factors, emission characterization, and fuel use. The total uncertainties are about a factor of two, with uncertainty ranges of 4.3 to 22 Tg/year for BC and 17 to 77 Tg/year for OC. Low-technology combustion contributes greatly to both the emissions and to the uncertainties. Advances in emission characterization for small residential, industrial, and mobile sources, and top-down analysis combining field measurements and transport modeling with iterative inventory development, will be required to reduce the uncertainties further.

An inventory of gaseous and primary aerosol emissions in Asia in the year 2000
D. G. Streets, T. C. Bond, G. R. Carmichael, S. D. Fernandes, Q. Fu, D. He, Z. Klimont, S. M. Nelson, N. Y. Tsai, M. Q. Wang, J.-H. Woo, and K. F. Yarber
 Journal of Geophysical Research, 108(D21), 8809, doi:10.1029/2002JD003093, 2003
An inventory of air pollutant emissions in Asia in the year 2000 is developed to support atmospheric modeling and analysis of observations taken during the TRACE-P experiment funded by the National Aeronautics and Space Administration (NASA) and the ACE-Asia experiment funded by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA). Emissions are estimated for all major contributing sources, including biomass burning, in 64 regions of Asia. We estimate total Asian emissions as follows: 34.3 Tg SO2, 26.8 Tg NOx, 9870 Tg CO2, 279 Tg CO, 107 Tg CH4, 52.2 Tg NMVOC, 2.54 Tg black carbon (BC), 10.4 Tg organic carbon (OC), and 27.5 Tg NH3. In addition, NMVOC are speciated into 19 sub-categories according to functional groups and reactivity. Thus, we are able to identify the major source regions and types for many of the significant gaseous and particle emissions that influence pollutant concentrations in the vicinity of the TRACE-P and ACE-Asia field measurements. Emissions in China dominate the signature of pollutant concentrations in this region, so special emphasis has been placed on the development of emission estimates for China. China’s emissions are determined to be as follows: 20.4 Tg SO2, 11.4 Tg NOx, 3820 Tg CO2, 116 Tg CO, 38.4 Tg CH4, 17.4 Tg NMVOC, 1.05 Tg BC, 3.4 Tg OC, and 13.6 Tg NH3. Emissions are gridded at a variety of spatial resolutions from 1º × 1º to 30 sec × 30 sec, using the exact locations of large point sources and surrogate GIS distributions of urban and rural population, road networks, land-cover, ship lanes, etc. The gridded emission estimates have been used as inputs to atmospheric simulation models and have proven to be generally robust in comparison with field observations, though there is reason to think that CO emissions may be under-estimated. Monthly emission estimates for China are developed for each species to aid TRACE-P and ACE-Asia data interpretation. During the observation period of March/April, emissions are roughly at their average values (one-twelfth of annual). Uncertainties in the emission estimates, measured as 95% confidence intervals, range from a low of ±16% for SO2 to a high of ±450% for OC.

Primary particle emissions from residential coal burning: optical properties and size distributions
Tami C. Bond, David S. Covert, John C. Kramlich, Timothy V. Larson, Robert J. Charlson
Journal of Geophysical Research, 107(D21), 8347, doi:10.1029/2001JD000571, 2002
Particles generated by combustion of fossil fuels contribute to climate forcing by absorbing and scattering visible light. Residential combustion takes place in homes for heating or cooking purposes and is thought to contribute a large fraction of the global burden of anthropogenic primary particles. We present optical properties and size distributions of particulate matter emitted from three types of coal burned in residential combustors: bituminous coal, hard coal briquettes and lignite. Emissions from these coals differ significantly and can be partially explained by differences in coal composition. For bituminous coal, particulate matter emission factors are somewhat greater than those used in current emission inventories. We observe particles for which the light absorption is weak and has a strong spectral dependence. For hard coal briquettes and lignite, emitted light absorption is low, and, based on our measurements, current inventories of light-absorbing aerosols significantly overestimate the contribution from these sources. Hard-coal briquettes produce very few particles in the optically-active size range. For all coals tested, the size distributions required to represent the average of the emitted particles are broader than atmospheric size distributions, with geometric standard deviations between 2.2 and 3.0.

Spectral dependence of visible light absorption by carbonaceous particles emitted from coal combustion
Tami C. Bond
Geophysical Research Letters 28 (21), 4075-4078, 2001.
Particles that absorb visible light affect the radiative balance of the Earth, and their optical characteristics are needed to model radiative effects. We explore the strong spectral dependence of light absorption at visible wavelengths observed in particles emitted from coal combustion. We find that a spectrally-dependent imaginary refractive index is the most plausible explanation. Following previous work on the structure of amorphous carbon, we propose that both absorption efficiency and spectral dependence are controlled by the extent of graphitic clusters within the material, and can be explained using the optical band-gap approximation. This hypothesis presents an alternative to the current dichotomy between light-absorbing “black carbon” and non-absorbing “organic carbon”.

Black Carbon Emissions in China
David G. Streets, Shalini Gupta, Stephanie T. Waldhoff, Michael Q. Wang, Tami C. Bond, and Bo Yiyun
Atmospheric Environment 35, 4281-4296, 2001.
Black carbon (BC) is an important aerosol species because of its global and regional influence on radiative forcing and its local effects on the environment and human health. We have estimated the emissions of black carbon in China, where roughly one-fourth of global anthropogenic emissions is believed to originate. China’s high rates of usage of coal and biofuels are primarily responsible for high BC emissions. This paper pays particular attention to the application of appropriate emission factors for China and the attenuation of these emissions where control devices are used. Nevertheless, because of the high degree of uncertainty associated with BC emission factors, we provide ranges of uncertainty for our emission estimates, which are approximately a factor of eight. In our central case, we calculate that BC emissions in China in 1995 were 1,342 Gg, about 83% being generated by the residential combustion of coal and biofuels. We estimate that BC emissions could fall to 1,224 Gg by 2020. This 9% decrease in BC emissions can be contrasted with the expected increase of 50% in energy use; the reduction will be obtained because of a transition to more advanced technology, including greater use of coal briquettes in place of raw coal in cities and towns. The increased use of diesel vehicles in the future will result in a greater share of the transport sector in total BC emissions. Spatially, BC emissions are predominantly distributed in an east-west swath across China’s heartland, where the rural use of coal and biofuels for cooking and heating is widespread. This is in contrast to the emissions of most other anthropogenically derived air pollutants, which are closely tied to population and industrial centers.

Climate-Relevant Particulate Emission Characteristics of a Coal-Fired Heating Plant
B.  Wehner, T. C. Bond, W. Birmili, J. Heintzenberg, A. Wiedensohler, and R.J. Charlson
Environmental Science and Technology, 33, 3881-3886, September 1999
Studies of climate forcing by anthropogenic aerosols require knowledge of the number and properties of the emitted primary aerosol particles. Previous measurements, often limited by instrumental techniques, did not extend far into the nanometer range and considered modern sources with air pollution controls. In the summer of 1996, aerosol size distributions were measured between 3 and 700 nm particle diameter in the exhaust of a low-technology coal-fired heating plant in Leipzig (Germany) using a Twin Differential Mobility Particle Sizer (TDMPS)-System. The total number concentration of particles in the exhaust was approximately 107 particles/ cm3, which is an order of magnitude lower than a previously published calculation based on a nucleation/condensation model. An estimate for the number concentration of primary combustion aerosol particles demonstrates the potential importance of such anthropogenic sources.

Light Absorption by Primary Particle Emissions from a Lignite Burning Plant
T.C. Bond, M. Bussemer, B. Wehner, S. Keller, R. J. Charlson, and J. Heintzenberg
Environmental Science and Technology, 33, 3887-3891, September 1999
Anthropogenic aerosols from the burning of fossil fuels contribute to climate forcing by both scattering and absorbing solar radiation, and estimates of climate forcing by light-absorbing primary particles have recently been published. While the mass and optical properties of emissions are needed for these studies, the available measurements do not characterize the low-technology burning that is thought to contribute a large fraction of light-absorbing material to the global budget. We have measured characteristics of particulate matter (PM) emitted from a small, low-technology lignite-burning plant. The PM emission factor is comparable to those used to calculate emission inventories of light-absorbing particles. However, the fine fraction, the absorbing fraction, and the absorption efficiency of the emissions are substantially below assumptions that have been made in inventories of black carbon emissions and calculations of climate forcing. The measurements suggest that non-black, light-absorbing particles are emitted from low-technology coal burning. As the burning rate increases, the emitted absorption cross-section decreases, and the wavelength dependence of absorption becomes closer to that of black particles.

Calibration and Intercomparison of Filter-Based Measurements of Visible Light Absorption by Aerosols 
Tami C. Bond, Theodore L. Anderson, and Dave Campbell
Aerosol Science and Technology, 30, 582-600, June 1999
Data on light absorption by atmospheric particles are scarce relative to the need for global characterization. Most of the existing data come from methods that measure the change in light transmission through a filter on which particles are collected. We present a calibration of a recently developed instrument for continuous measurement of light absorption (model PSAP, Radiance Research, Seattle, WA) that has been incorporated in several measurement programs. This calibration uses a reference absorption determined as the difference between light extinction and light scattering by unaltered (suspended) particles. In addition, we compare the calibrated PSAP measurement to absorption measurements by two other common filter-based methods: an Integrating Plate and a Laser Integrating Plate. For each method, we assess the responses to both particulate light scattering and particulate light absorption. We find that each of the instruments exhibits a significant response to non-absorbing aerosols and overestimates absorption at 550 nm by suspended particles by about 20%. We also present correction factors for the use of the PSAP.

Quantifying the emission of light-absorbing particles: Measurements tailored to climate studies
Tami C. Bond, Robert J. Charlson, and Jost Heintzenberg
Geophysical Research Letters, 25, 337-340, 1998
The emission rate of light-absorbing aerosols, which contribute to climate forcing, has previously been calculated using mass emission factors combined with fuel-use inventories. Several assumptions made in this calculation lead to overestimates that are significant, but as yet unevaluated. We propose a new measurement approach that augments, and may be preferable to, the mass-based method for modeling radiative forcing by aerosols: direct measurement of the source strength of absorption. This quantity, in units of absorption cross-section per unit time, may be used directly in models of atmospheric dispersion and transport to predict the three-dimensional, time-dependent distribution of the absorption of visible light by aerosols. In demonstration measurements made at a coal-burning plant, the emitted absorption is an order of magnitude lower than would be inferred from the previous method of calculation.

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