1. Black Carbon:Global Budget and Impacts on Climate

2. Soot Particle from a Wood- Burning Stove

3. Scanning electron microscope image of particles collected in Xianghe, W of Beijing.

4. Structure of Soot

5. Outline Soot: What is it? Climate Impact Physics Prior budgets INDOEX Budget evaluation Conclusions

7. Climate forcing for atmospheric gases and aerosols IPCC (2001) Forcing Agent Climate Forcing Wm -2 (Up to year 2000) Greenhouse Gas CO 2 1.3 to 1.5 CH 4 0.5 to 0.7 Tropos. O 3 0.25 to 0.75 N2ON2O0.1 to 0.2 Fine Aerosol SO 4 2- – 0.3 to –1.0 Black Carbon0.1 to 0.8* *Jacobson Nature, 2001.

8. Radiation and fine particles

9. Optical Properties & Visibility Change in intensity of light reflecting off an object  I / I = exp( ‑ b ext  X) where: I = incident intensity of light  I = change in intensity of light b ext = extinction coefficient (m ‑ 1 )  X = distance (m)

10. Extinction Coefficient, b ext Sum of scattering and absorption coefficients: b ext = b scat + b abs Decomposed further from gases and particles: b abs = b ag + b ap b scat = b sg + b sp Where: b ag = absorption coefficient due to gases (Beer's law) b ap = absorption coefficient due to particles b sg = scattering coefficient due to gases (Rayleigh scattering) b sp = scattering coefficient due to particles (Mie scattering)

11. Atmospheric Aerosols

12. Optical Properties of Small Particles  = b scat /b ext  = Single scattering albedo m = n + ik m = complex index of refraction n = scattering (real part) k = absorption (imaginary part)

13. Refractive indicies of aerosol particles at = 589 nm m = n + ik Substancenk Water1.33310 -8 Ice1.30910 -8 NaCl1.5440 H 2 SO 4 1.4260 NH 4 HSO 4 1.4730 (NH 4 ) 2 SO41.5210 SiO 2 1.550 Black Carbon (soot)1.960.66 Mineral dust~1.53~0.006

14. Radiative Effects (Climate Impact) of Soot External mixture +0.27 Wm -2 Coated core +0.54 Wm -2 Well-mixed internally +0.78 Wm -2 (Jacobson, GRL., 2000)

15. External vs. Internal Mixtures Sulfate & Soot mixed externally. Soot with sulfate coating (coated core). Well-mixed internally.

16. Global Fossil Fuel Black Carbon Emissions (Cooke et al., JGR., 1999; Penner et al., 1993) RegionBC Emissions Tg yr -1 W. Europe0.58 Eastern Europe0.68 Africa0.17 N. America0.49 C. & S. America0.26 Former USSR0.69 China & Oceania1.18 Rest of Asia0.89 Total fossil fuel5.06 Biomass Burning5.97

17. Indian Today, 1996

18. INDOEX, 1999 INDOEX Experimental Design

19. NOAA R/V Ronald Brown

20. Impactor Samples from Ship during INDOEX

22. Origin of Soot? Low single scattering albedo, 0.81, indicates 70% from fossil fuel combustion (Mayol-Bracero et al, 2001). Ratio of BC/OC near unity means origin should be fossil fuel combustion (Novakov et al., 2001).

23. Emissions Inventories Gg yr -1 Black Carbon from South Asia High Estimate for 1999 IndustryDomesticMobile Sources Power Generation Field Combustion Total 2635501392.7371009

25. Estimate of BC Emission from Ambient Measurements E BC = E CO *[BC]/[CO]/L BC Fort Meade, MD E BC = 90 Tg(CO)/yr * 0.0034 = 0.31 Tg(BC)/yr for N America (vs. 0.49 Tg(BC)/yr) INDOEX E BC = 87 Tg(CO)/yr * 0.0125/0.5 = 2.2 Tg(BC)/yr for South Asia (vs. 0.5 to 1Tg(BC)/yr)

29. Two-Stroke Engine No Valves Oil mixed with gasoline Part of fresh charged exhausted Fuel adulteration

30. 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

31. The ambient EC concentration decreases ~50% in the recent 11 years.

32. The ambient OC concentration decreases ~10% in the recent 11 years.

33. EC and OC are correlated (95-00) but show no obvious trend.

34. EC shows a decreasing trend but no correlation with OC.

35. At SHEN, EC decrease by ~15% in 8 years (1989-1997) while CO decrease by ~ 20% during the same period.

36. Summary Black Carbon (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 Tg(BC) a -1. Ambient measurements suggest major role for biomass burning and indicate 2-3 Tg(BC) a -1. Combustion in S Asia is unlike anything seen in N America or Europe. Time for direct measurements.

37. Black Carbon References