Black Carbon:Global Budget and Impacts on Climate Soot Particle from a Wood-Burning Stove Scanning electron microscope image of particles collected in Xianghe, W of Beijing. Structure of Soot Outline
Soot: What is it? Climate Impact Physics Prior budgets
INDOEX Budget evaluation Conclusions Figure 4. Climate forcing agents in the industrial era. Error bars are partly subjective 1 (standard deviation) uncertainties. (standard deviation) uncertainties.standard deviation) uncertainties. Increases of well-mixed greenhouse gases (standard deviation) uncertainties.excludes O3) are known accurately from in situ observations and bubbles of air trapped in ice sheets. For example, the increase of CO 2 from 285 parts per million (standard deviation) uncertainties.ppm) in 1 (standard deviation) uncertainties.850 to 368 ppm in 2000 is accurate to about 5 ppm. The conversion of this gas change to a climate forcing (standard deviation) uncertainties.1 (standard deviation) uncertainties..4 W/m2), from calculation of the infrared opacity, adds about 1 (standard deviation) uncertainties.0% to the uncertainty.
The CH4 increase since 1 (standard deviation) uncertainties.850, including its effect on stratospheric H2O and tropospheric O3, causes a climate forcing half as large as that by CO 2. Principal anthropogenic sources of CH4 are landfills, coal mining, leaky natural gas lines, increasing ruminant population, rice cultivation, and anaerobic waste management lagoons. In the last decade the growth rate of CH4 has slowed, suggesting that the growth of sources is slowing. Tropospheric O3 is increasing partly because CH4 is increasing, but the primary cause is other human-made emissions, especially carbon monoxide, nitrogen oxides, and volatile organic Climate forcing for atmospheric gases and aerosols IPCC (standard deviation) uncertainties.2001 (standard deviation) uncertainties.) Forcing Agent
Climate Forcing Wm-2 (Up to year 2000) Greenhouse Gas CO2 1.3 to 1.5 CH4 0.5 to 0.7
Tropos. O3 N2 O 0.25 to 0.75 0.1 to 0.2 Fine Aerosol SO4 2Black Carbon *Jacobson Nature, 2001. 0.3 to 1.0 0.1 to 0.8*
Radiation and fine particles Optical Properties & Visibility Change in intensity of light reflecting off an object I / I = exp(standard deviation) uncertainties.bext X) where: I = incident intensity of light I = change in intensity of light bext = extinction coefficient (m1) X
= distance (m) Extinction Coefficient, bext Sum of scattering and absorption coefficients: bext = bscat + babs Decomposed further from gases and particles: babs = bag + bap bscat = bsg + bsp Where: bag = absorption coefficient due to gases (standard deviation) uncertainties.Beer's law) bap = absorption coefficient due to particles
bsg = scattering coefficient due to gases (standard deviation) uncertainties.Rayleigh scattering) bsp = scattering coefficient due to particles (standard deviation) uncertainties. Mie scattering) Atmospheric Aerosols Optical Properties of Small Particles = bscat/bext = Single scattering albedo m = n + ik m = complex index of refraction n = scattering (standard deviation) uncertainties.real part)
k = absorption (standard deviation) uncertainties.imaginary part) Refractive indicies of aerosol particles at = 589 nm Substance m = n + ik n k Water
1.333 10-8 Ice 1.309 10-8 NaCl
1.544 0 H2SO4 1.426 0 NH4HSO4
1.473 0 (NH4)2SO4 1.521 0 SiO2
1.55 0 Black Carbon (soot) 1.96 0.66 Mineral dust
~1.53 ~0.006 Radiative Effects (standard deviation) uncertainties.Climate Impact) of Soot External mixture +0.27 Wm-2 Coated core +0.54 Wm-2 Well-mixed internally +0.78 Wm-2 (standard deviation) uncertainties.Jacobson, GRL., 2000) External vs. Internal Mixtures Sulfate & Soot
mixed externally. Soot with sulfate coating (coated core). Well-mixed internally. Global Fossil Fuel Black Carbon Emissions (standard deviation) uncertainties.Cooke et al., JGR., 1 (standard deviation) uncertainties.999; Penner et al., 1 (standard deviation) uncertainties.993) Region BC Emissions Tg yr-1
W. Europe 0.58 Eastern Europe 0.68 Africa 0.17
N. America 0.49 C. & S. America 0.26 Former USSR 0.69
China & Oceania 1.18 Rest of Asia 0.89 Total fossil fuel 5.06
Biomass Burning 5.97 Indian Today, 1 (standard deviation) uncertainties.996 INDOEX Experimental Design INDOEX, 1 (standard deviation) uncertainties.999
NOAA R/V Ronald Brown Impactor Samples from Ship during INDOEX Origin of Soot? Ratio of BC/OC near unity means origin should be fossil fuel combustion (standard deviation) uncertainties.Novakov et al., 2001 (standard deviation) uncertainties.). Low single scattering albedo, 0.81 (standard deviation) uncertainties., indicates 70% from fossil fuel combustion (standard deviation) uncertainties.Mayol-Bracero et al, 2001 (standard deviation) uncertainties.). Emissions Inventories
Gg yr-1 (standard deviation) uncertainties. Black Carbon from South Asia High Estimate for 1 (standard deviation) uncertainties.999 Industry Domestic 263 550 Mobile Sources 139
Power Field Generation Combustion 2.7 37 Total 1009
CO vs BC (total) from Ship During INDOEX 2.50 INDOEX (Spring) Mace Head (Spring) FME (annual) Total BC ( g m-3) 2.00 1.50 INDOEX Ship
y = 0.0125x - 1.23 1.00 R2 = 0.74 0.50 0.00 50 100
150 200 CO ( g m-3) 250 300 350 Estimate of BC Emission
from Ambient Measurements EBC = ECO*[BC]/[CO]/LBC Fort Meade, MD EBC = 90 Tg(standard deviation) uncertainties.CO)/yr * 0.0034 = 0.31 Tg(standard deviation) uncertainties.BC)/yr for N America (standard deviation) uncertainties.vs. 0.49 Tg(standard deviation) uncertainties.BC)/yr) INDOEX EBC = 87 Tg(standard deviation) uncertainties.CO)/yr * 0.01 (standard deviation) uncertainties.25/0.5 = 2.2 Tg(standard deviation) uncertainties.BC)/yr for South Asia (standard deviation) uncertainties.vs. 0.5 to 1 (standard deviation) uncertainties.Tg(standard deviation) uncertainties.BC)/yr) CO vs. BC from KCO During INDOEX
3.50 3.00 BC ( g m-3 ) 2.50 y = 0.021x - 2.97 2.00 R2 = 0.72
1.50 1.00 0.50 y = 0.015x - 2.31 R2 = 0.81 0.00 50 100 150
200 CO ( g m-3) 250 300 CO vs BC from C130 During INDOEX 7.0 6.0
y = 0.027x - 3.73 2 R = 0.71 BC ( g m-3) 5.0 4.0 3.0
2.0 1.0 0.0 50 100 150 200
250 -3 CO ( g m ) 300 350 Two-Stroke Engine No Valves
Oil mixed with gasoline Part of fresh charged exhausted Fuel adulteration Source Strength Black Carbon in China Estimated annual BC emissions from China: 1300-2600 Gg/yr Inventory: 1049 Gg/yr [Streets et al., 2003]
Better agreement compared to a similar study for India [Dickerson et al., 2002] Single Scattering Albedo (SSA): Morning: ~0.81, Afternoon: ~0.85 The ambient EC concentration decreases ~50% in the recent 1 (standard deviation) uncertainties.1 (standard deviation) uncertainties. years. The ambient OC concentration decreases ~1 (standard deviation) uncertainties.0% in the recent 1 (standard deviation) uncertainties.1 (standard deviation) uncertainties. years.
EC and OC are correlated (standard deviation) uncertainties.95-00) but show no obvious trend. EC shows a decreasing trend but no correlation with OC. At SHEN, EC decrease by ~1 (standard deviation) uncertainties.5% in 8 years (standard deviation) uncertainties.1 (standard deviation) uncertainties.989-1 (standard deviation) uncertainties.997) while CO decrease by ~ 20% during the same period. Summary Black Carbon (standard deviation) uncertainties.soot) may provide more forcing than methane. Properties of aerosols suggest that fossil fuel combustion is main
source of black carbon from South Asia. Inventories suggest biofuels contribute substantially, and cannot support emissions above 1 (standard deviation) uncertainties. Tg(standard deviation) uncertainties.BC) a-1 (standard deviation) uncertainties.. Ambient measurements suggest major role for biomass burning and indicate 2-3 Tg(standard deviation) uncertainties.BC) a-1 (standard deviation) uncertainties.. Combustion in S Asia is unlike anything seen in N America or Europe. Time for direct measurements. Black Carbon References
