Atmospheric Chemistry and Physics
www.atmos-chem-phys.net
1680-7316
1680-7324
11
4
2011
10.5194/acp-11-1505-2011
http://www.atmos-chem-phys.net/11/1505/2011/
http://www.atmos-chem-phys.net/11/1505/2011/acp-11-1505-2011.html
http://www.atmos-chem-phys.net/11/1505/2011/acp-11-1505-2011.pdf
1505
1525
2011-02-16
Quantifying immediate radiative forcing by black carbon and organic matter with the Specific Forcing Pulse
T. C. Bond
yark@illinois.edu
C. Zarzycki
M. G. Flanner
D. M. Koch
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA
Department of Atmospheric, Oceanic and Space Sciences, University of Michigan Ann Arbor, Michigan, USA
NASA Goddard Institute for Space Studies, Columbia University, New York, USA
Climatic effects of short-lived climate forcers (SLCFs) differ from those of
long-lived greenhouse gases, because they occur rapidly after emission and
because they depend upon the region of emission. The distinctive temporal
and spatial nature of these impacts is not captured by measures that rely on
global averages or long time integrations. Here, we propose a simple
measure, the Specific Forcing Pulse (SFP), to quantify climate warming or
cooling by these pollutants, where we define "immediate" as occurring
primarily within the first year after emission. SFP is the amount of energy
added to or removed from a receptor region in the Earth-atmosphere system by
a chemical species, per mass of emission in a source region. We limit the
application of SFP to species that remain in the atmosphere for less than
one year. Metrics used in policy discussions, such as total forcing or
global warming potential, are easily derived from SFP. However, SFP conveys
purely physical information without incurring the policy implications of
choosing a time horizon for the global warming potential.
<br></br>
Using one model (Community Atmosphere Model, or CAM), we calculate values of
SFP for black carbon (BC) and organic matter (OM) emitted from 23
source-region combinations. Global SFP for both atmosphere and cryosphere
impacts is divided among receptor latitudes. SFP is usually greater for
open-burning emissions than for energy-related (fossil-fuel and biofuel)
emissions because of the timing of emission. Global SFP for BC varies by
about 45% for energy-related emissions from different regions. This
variation would be larger except for compensating effects. When emitted
aerosol has larger cryosphere forcing, it often has lower atmosphere forcing
because of less deep convection and a shorter atmospheric lifetime.
<br></br>
A single model result is insufficient to capture uncertainty. We develop a
best estimate and uncertainties for SFP by combining forcing results from 12
additional models. We outline a framework for combining a large number of
simple models with a smaller number of enhanced models that have greater
complexity. Adjustments for black carbon internal mixing and for regional
variability are discussed. Emitting regions with more deep convection have
greater model diversity. Our best estimate of global-mean SFP is +1.03 ± 0.52 GJ g<sup>−1</sup>
for direct atmosphere forcing of black carbon, +1.15 ± 0.53 GJ g<sup>−1</sup> for black carbon including direct and cryosphere forcing,
and −0.064 (−0.02, −0.13) GJ g<sup>−1</sup> for organic matter. These values depend
on the region and timing of emission. The lowest OM:BC mass ratio required
to produce a neutral effect on top-of-atmosphere direct forcing is 15:1 for
any region. Any lower ratio results in positive direct forcing. However,
important processes, particularly cloud changes that tend toward cooling,
have not been included here.
<br></br>
Global-average SFP for energy-related emissions can be converted to a
100-year GWP of about 740 ± 370 for BC without snow forcing, and 830 ± 440
with snow forcing. 100-year GWP for OM is −46 (−18, −92). Best estimates
of atmospheric radiative impact (without snow forcing) by black and organic
matter are +0.47 ± 0.26 W m<sup>−2</sup> and −0.17 (−0.07, −0.35) W m<sup>−2</sup>
for BC and OM, respectively, assuming total emission rates of 7.4 and
45 Tg yr<sup>−1</sup>. Anthropogenic forcing is +0.40 ± 0.18 W m<sup>−2</sup> and −0.13
(−0.05, −0.25) W m<sup>−2</sup> for BC and OM, respectively, assuming anthropogenic
emission rates of 6.3 and 32.6 Tg yr<sup>−1</sup>. Black carbon forcing is only
18% higher than that given by the Intergovernmental Panel on Climate
Change (IPCC), although the value presented here includes enhanced
absorption due to internal mixing.
Ackerman, T. P. and Toon, O. B.: Absorption of visible radiation in atmosphere containing mixtures of absorbing and nonabsorbing particles, Appl. Opt., 20, 3661–3667, 1981.
Adachi, K., Chung, S. H., and Buseck, P. R.: Shapes of soot aerosol particles and implications for their effects on climate, J. Geophys. Res.-Atmos., 115, D15206, http://dx.doi.org/10.1029/2009jd012868doi:10.1029/2009jd012868, 2010.
Alcamo, J., van den Born, G. J., Bouwman, A. F., de Haan, B. J., Klein Goldewijk, K., Klepper, O., Krabec, J., Leemans, R., Olivier, J. G. J., Toet, A. M. C., Vries, H. J. M. d., and Woerd, H. J. v. d.: Modeling the global society-biosphere-climate system: Part 2: Computed scenarios, Water Air Soil Poll., 76, 37–78, 1994.
Berntsen, T., Fuglestvedt, J., Myhre, G., Stordal, F., and Berglen, T. F.: Abatement of greenhouse gases: does location matter?, J. Clim., 74, 377–411, 2006.
Bond, T. C. and Bergstrom, R. W.: Light absorption by carbonaceous particles: an investigative review, Aerosol Sci. Tech., 40, 27–67, 2006.
Bond, T. C. and Sun, H.: Can reducing black carbon emissions counteract global warming?, Environ. Sci. Tech., 39, 5921–5926, 2005.
Bond, T. C., Streets, D. G., Yarber, K. F., Nelson, S. M., Woo, J.-H., and Klimont, Z.: A technology-based global inventory of black and organic carbon emissions from combustion, J. Geophys. Res., 109, D14203, doi:14210.11029/12003JD003697, 2004.
Bond, T. C., Habib, G., and Bergstrom, R. W.: Limitations in the enhancement of visible light absorption due to mixing state, J. Geophys. Res., 111, D20211, doi:20210.21029/22006JD007315, 2006.
Bond, T. C., Bhardwaj, E., Dong, R., Jogani, R., Jung, S., Roden, C., Streets, D. G., Fernandes, S., and Trautmann, N.: Historical emissions of black and organic carbon aerosol from energy-related combustion, 1850–2000, Glob. Biogeochem. Cyc., 21, GB2018, doi:2010.1029/2006GB002840, 2007.
Boucher, O. and Reddy, M. S.: Climate trade-off between black carbon and carbon dioxide emissions, Energ. Policy, 36, 193–200, 2008.
Chen, W.-T., Lee, Y. H., Adams, P. J., Nenes, A., and Seinfeld, J. H.: Will black carbon mitigation dampen aerosol indirect forcing? Geophys. Res. Lett., 37(9), L09801, http://dx.doi.org/10.1029/2010GL042886doi:10.1029/2010GL042886, 2010.
Chung, C. E., Ramanathan, V., and Kiehl, J. T.: Effects of the South Asian absorbing haze on the northeast monsoon and surface – air heat exchange, J. Clim., 15, 2462–2476, 2002.
Chung, S. H. and Seinfeld, J. H.: Global distribution and climate forcing of carbonaceous aerosols, J. Geophys. Res., 107, 4407–4441, 2002.
Collins, W. D., Rasch, P. J., Boville, B. A., Hack, J. J., McCaa, J. R., Williamson, D. L., and Briegleb, B. P.: The formulation and atmospheric simulation of the Community Atmosphere Model Version 3 (CAM3), J. Clim., 19, 2144–2161, 2006.
Dentener, F., Kinne, S., Bond, T., Boucher, O., Cofala, J., Generoso, S., Ginoux, P., Gong, S., Hoelzemann, J. J., Ito, A., Marelli, L., Penner, J. E., Putaud, J.-P., Textor, C., Schulz, M., van der Werf, G. R., and Wilson, J.: Emissions of primary aerosol and precursor gases in the years 2000 and 1750 prescribed data-sets for AeroCom, Atmos. Chem. Phys., 6, 4321–4344, http://dx.doi.org/10.5194/acp-6-4321-2006doi:10.5194/acp-6-4321-2006, 2006.
Fasullo, J. T. and Trenberth, K. E.: The annual cycle of the energy budget. Part I: Global mean and land-ocean exchanges, J. Clim., 21, 2297–2312, http://dx.doi.org/10.1175/2007jcli1935.1doi:10.1175/2007jcli1935.1, 2008.
Flanner, M. G., Zender, C. S., Randerson, J. T., and Rasch, P. J.: Present-day climate forcing and response from black carbon in snow, J. Geophys. Res., 112, D11202, doi:11210.11029/12006JD008003, 2007.
Flanner, M. G., Zender, C. S., Hess, P. G., Mahowald, N. M., Painter, T. H., Ramanathan, V., and Rasch, P. J.: Springtime warming and reduced snow cover from carbonaceous particles, Atmos. Chem. Phys., 9, 2481–2497, http://dx.doi.org/10.5194/acp-9-2481-2009doi:10.5194/acp-9-2481-2009, 2009.
Forster, P. M. D. and Taylor, K. E.: Climate forcings and climate sensitivities diagnosed from coupled climate model integrations, J. Clim., 19, 6181–6194, 2006.
Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betta, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Van Dorland, R.: Changes in atmospheric constituents and in radiative forcing, in: Climate change 2007: The physical science basis, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tigor, M., and Miller, H. L., Cambridge University Press, Cambridge, UK, 129–234, 2007.
Fuglestvedt, J. S., Shine, K. P., Berntsen, T., Cook, J., Lee, D. S., Stenke, A., Skeie, R. B., Velders, G. J. M., and Waitz, I. A.: Transport impacts on atmosphere and climate: Metrics, Atmos. Env., 44, 4648–4677, http://dx.doi.org/10.1016/j.atmosenv.2009.04.044doi:10.1016/j.atmosenv.2009.04.044, 2010.
Grieshop, A. P., Reynolds, C. C. O., Kandlikar, M., and Dowlatabadi, H.: A black-carbon mitigation wedge, Nat. Geosci., 2, 533–534, 2009.
Hansen, J. and Nazarenko, L.: Soot climate forcing via snow and ice albedos, Proc. Natl. Acad. Sci., 101, 423–428, 2004.
Hansen, J., Sato, M., and Ruedy, R.: Radiative forcing and climate response, J. Geophys. Res.-Atmos., 102, 6831–6864, 1997.
Hansen, J. E., Sato, M., Ruedy, R., Lacis, A., and Oinas, V.: Global warming in the twenty-first century: an alternative scenario, Proc. Natl. Acad. Sci., 97, 9875–9880, 2000.
Hansen, J., Sato, M., Ruedy, R., Nazarenko, L., Lacis, A., Schmidt, G. A., Russell, G., Aleinov, I., Bauer, M., Bauer, S., Bell, N., Cairns, B., Canuto, V., Chandler, M., Cheng, Y., Del Genio, A., Faluvegi, G., Fleming, E., Friend, A., Hall, T., Jackman, C., Kelley, M., Kiang, N., Koch, D., Lean, J., Lerner, J., Lo, K., Menon, S., Miller, R., Minnis, P., Novakov, T., Oinas, V., Perlwitz, J., Rind, D., Romanou, A., Shindell, D., Stone, P., Sun, S., Tausnev, N., Thresher, D., Wielicki, B., Wong, T., Yao, M., and Zhang, S.: Efficacy of climate forcings, J. Geophys. Res.-Atmos., 110, D18104, doi:18110.11029/12005jd005776, 2005.
Jacobson, M. Z.: A physically-based treatment of elemental carbon optics: implications for global direct forcing of aerosols, Geophys. Res. Let., 27, 217–220, 2000.
Jacobson, M. Z.: Climate response of fossil fuel and biofuel soot, accounting for soot's feedback to snow and sea ice albedo and emissivity, J. Geophys. Res., 109, D21201, doi:21210.21029/22004JD004945, 2004.
Jacobson, M. Z.: Effects of absorption by soot inclusions within clouds and precipitation on global climate, J. Phys. Chem., 110, 6860–6873, 2006.
Jimenez, J. L., Canagaratna, M. R., Donahue, N. M., Prevot, A. S. H., Zhang, Q., Kroll, J. H., DeCarlo, P. F., Allan, J. D., Coe, H., Ng, N. L., Aiken, A. C., Docherty, K. S., Ulbrich, I. M., Grieshop, A. P., Robinson, A. L., Duplissy, J., Smith, J. D., Wilson, K. R., Lanz, V. A., Hueglin, C., Sun, Y. L., Tian, J., Laaksonen, A., Raatikainen, T., Rautiainen, J., Vaattovaara, P., Ehn, M., Kulmala, M., Tomlinson, J. M., Collins, D. R., Cubison, M. J., Dunlea, E. J., Huffman, J. A., Onasch, T. B., Alfarra, M. R., Williams, P. I., Bower, K., Kondo, Y., Schneider, J., Drewnick, F., Borrmann, S., Weimer, S., Demerjian, K., Salcedo, D., Cottrell, L., Griffin, R., Takami, A., Miyoshi, T., Hatakeyama, S., Shimono, A., Sun, J. Y., Zhang, Y. M., Dzepina, K., Kimmel, J. R., Sueper, D., Jayne, J. T., Herndon, S. C., Trimborn, A. M., Williams, L. R., Wood, E. C., Middlebrook, A. M., Kolb, C. E., Baltensperger, U., and Worsnop, D. R.: Evolution of Organic Aerosols in the Atmosphere, Science, 326, 1525–1529, http://dx.doi.org/10.1126/science.1180353doi:10.1126/science.1180353, 2009.
Jones, A., Haywood, J. M., and Boucher, O.: Aerosol forcing, climate response and climate sensitivity in the Hadley Centre climate model, J. Geophys. Res.-Atmos., 112, D20211, http://dx.doi.org/10.1029/2007jd008688doi:10.1029/2007jd008688, 2007.
Kirchstetter, T. W., Novakov, T., and Hobbs, P. V.: Evidence that the spectral dependence of light absorption by aerosols is affected by organic carbon, J. Geophys. Res., 109, D21208, doi:21210.21029/22004JD004999, 2004.
Koch, D. and Del Genio, A.: Black carbon absorption effects on cloud cover, review and synthesis, Atmos. Chem. Phys. Discuss., 10, 7323–7346, http://dx.doi.org/10.5194/acpd-10-7323-2010doi:10.5194/acpd-10-7323-2010, 2010.
Koch, D., Bond, T. C., Streets, D., Unger, N., and van der Werf, G. R.: Global impacts of aerosols from particular source regions and sectors, J. Geophys. Res., 112, D02205, doi:02210.01029/02005JD007024, 2007.
Koch, D., Menon, S., Del Genio, A., Ruedy, R., Alienov, I., and Schmidt, G. A.: Distinguishing aerosol impacts on climate over the past century, J. Clim., 22, 2659–2677, http://dx.doi.org/10.1175/2008jcli2573.1doi:10.1175/2008jcli2573.1, 2009.
Kopp, R. E. and Mauzerall, D. L.: Assessing the climatic benefits of black carbon mitigation, Proc. Natl. Acad. Sci., 107, 11703–11708, http://dx.doi.org/10.1073/pnas.0909605107doi:10.1073/pnas.0909605107, 2010.
Lohmann, U., Rotstayn, L., Storelvmo, T., Jones, A., Menon, S., Quaas, J., Ekman, A. M. L., Koch, D., and Ruedy, R.: Total aerosol effect: radiative forcing or radiative flux perturbation?, Atmos. Chem. Phys., 10, 3235–3246, http://dx.doi.org/10.5194/acp-10-3235-2010doi:10.5194/acp-10-3235-2010, 2010.
Maria, S. F., Russell, L. M., Gilles, M. K., and Myneni, S. C. B.: Organic aerosol growth mechanisms and their climate-forcing implications, Science, 306, 1921–1924, 2004.
Meehl, G. A., Arblaster, J. M., and Collins, W. D.: Effects of black carbon aerosols on the Indian Monsoon, J. Clim., 21, 2869–2882, 2008.
Moffet, R. C. and Prather, K. A.: In-situ measurements of the mixing state and optical properties of soot with implications for radiative forcing estimates, Proc. Natl. Acad. Sci., 106, 11872–11877, 2009.
Murphy, D. M., Solomon, S., Portmann, R. W., Rosenlof, K. H., Forster, P. M., and Wong, T.: An observationally based energy balance for the Earth since 1950, J. Geophys. Res.-Atmos., 114, D17107, http://dx.doi.org/10.1029/2009jd012105doi:10.1029/2009jd012105, 2009.
Myhre, G., Berglen, T. F., Johnsrud, M., Hoyle, C. R., Berntsen, T. K., Christopher, S. A., Fahey, D. W., Isaksen, I. S. A., Jones, T. A., Kahn, R. A., Loeb, N., Quinn, P., Remer, L., Schwarz, J. P., and Yttri, K. E.: Modelled radiative forcing of the direct aerosol effect with multi-observation evaluation, Atmos. Chem. Phys., 9, 1365–1392, http://dx.doi.org/10.5194/acp-9-1365-2009doi:10.5194/acp-9-1365-2009, 2009.
Naik, V., Mauzerall, D. L., Horowitz, L. W., Schwarzkopf, M. D., Ramaswamy, V., and Oppenheimer, M.: On the sensitivity of radiative forcing from biomass burning aerosols and ozone to emission location, Geophys. Res. Let., 34, L03818, http://dx.doi.org/10.1029/2006gl028149doi:10.1029/2006gl028149, 2007.
Quinn, P. K., Bates, T. S., Baum, E., Doubleday, N., Fiore, A. M., Flanner, M., Fridlind, A., Garrett, T. J., Koch, D., Menon, S., Shindell, D., Stohl, A., and Warren, S. G.: Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies, Atmos. Chem. Phys., 8, 1723–1725, 2008.
Ramanathan, V. and Carmichael, G.: Global and regional climate changes due to black carbon, Nat. Geosci., 1, 221–227, 2008.
Reddy, M. S. and Boucher, O.: Climate impact of black carbon emitted from energy consumption in the world's regions, Geophys. Res. Let., 34, L11802, doi:11810.11029/12006GL028904, 2007.
Rypdal, K., Rive, N., Berntsen, T., Fagerli, H., Klimont, Z., Mideksa, T. K., and Fuglestvedt, J. S.: Climate and air quality-driven scenarios of ozone and aerosol precursor abatement, Environ. Sci. Policy., 12, 855–869, http://dx.doi.org/10.1016/j.envsci.2009.08.002doi:10.1016/j.envsci.2009.08.002, 2009.
Saikawa, E., Naik, V., Horowitz, L. W., Liu, J., and Mauzerall, D. L.: Present and potential future contributions of sulfate, black and organic carbon aerosols from China to global air quality, premature mortality and, radiative forcing, Atmos. Env., 43, 2814–2822, http://dx.doi.org/10.1016/j.atmosenv.2009.02.017doi:10.1016/j.atmosenv.2009.02.017, 2009.
Sato, M., Hansen, J., Koch, D., Lacis, A., Ruedy, R., Dubovik, O., Holben, B., Chin, M., and Novakov, T.: Global atmospheric black carbon inferred from AERONET, Proc. Natl. Acad. Sci., 100, 6319–6324, 2003.
Schnaiter, M., Linke, C., Möhler, O., Naumann, K.-H., Saathoff, H., Wagner, R., Schurath, U., and Wehner, B.: Absorption amplification of black carbon internally mixed with secondary organic aerosol, J. Geophys. Res., 110, D19204, doi:19210.11029/12005JD006046, 2005.
%Schulz, M., Textor, C., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., %Berglen, T., Boucher, O., Dentener, F., Guibert, S., Isaksen, I. S. A., %Iversen, T., Koch, D., Kirkevåg, A., Liu, X., Montanaro, V., Myhre, G., %Penner, J. E., Pitari, G., Reddy, S., Seland, Ø., Stier, P., and %Takemura, T.: Radiative forcing by aerosols as derived from the AeroCom %present-day and pre-industrial simulations, Atmos. Chem. Phys., 6, %5225-5246, 2006. Schulz, M., Textor, C., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Dentener, F., Guibert, S., Isaksen, I. S. A., Iversen, T., Koch, D., Kirkevåg, A., Liu, X., Montanaro, V., Myhre, G., Penner, J. E., Pitari, G., Reddy, S., Seland, Ø., Stier, P., and Takemura, T.: Radiative forcing by aerosols as derived from the AeroCom present-day and pre-industrial simulations, Atmos. Chem. Phys., 6, 5225–5246, http://dx.doi.org/10.5194/acp-6-5225-2006doi:10.5194/acp-6-5225-2006, 2006.
Shine, K. P., Cook, J., Highwood, E. J., and Joshi, M. M.: An alternative to radiative forcing for estimating the relative importance of climate change mechanisms, Geophys. Res. Let., 30, 2047, http://dx.doi.org/10.1029/2003gl018141doi:10.1029/2003gl018141, 2003.
Shine, K. P., Fuglestvedt, J. S., Hailemariam, K., and Stuber, N.: Alternatives to the global warming potential for comparing climate impacts of emissions of greenhouse gases, Clim. Change, 68, 281–302, 2005.
Shindell, D. and Faluvegi, G.: Climate response to regional radiative forcing during the twentieth century, Nat. Geosci., 2, 294–300, http://dx.doi.org/10.1038/ngeo473doi:10.1038/ngeo473, 2009.
Shindell, D. T., Chin, M., Dentener, F., Doherty, R. M., Faluvegi, G., Fiore, A. M., Hess, P., Koch, D. M., MacKenzie, I. A., Sanderson, M. G., Schultz, M. G., Schulz, M., Stevenson, D. S., Teich, H., Textor, C., Wild, O., Bergmann, D. J., Bey, I., Bian, H., Cuvelier, C., Duncan, B. N., Folberth, G., Horowitz, L. W., Jonson, J., Kaminski, J. W., Marmer, E., Park, R., Pringle, K. J., Schroeder, S., Szopa, S., Takemura, T., Zeng, G., Keating, T. J., and Zuber, A.: A multi-model assessment of pollution transport to the Arctic, Atmos. Chem. Phys., 8, 5353–5372, http://dx.doi.org/10.5194/acp-8-5353-2008doi:10.5194/acp-8-5353-2008, 2008.
Shiraiwa, M., Kondo, Y., Moteki, N., Takegawa, N., Miyazaki, Y., and Blake, D. R.: Evolution of mixing state of black carbon in polluted air from Tokyo, Geophys. Res. Let., 34, L16803, doi:16810.11029/12007GL029819, 2007.
Smith, S. J., Wigley, T. M. L., Nakicenovic, N., and Raper, S. C. B.: Climate implications of greenhouse gas scenarios, Tech Forecast Soc Change, 65, 195–204, 2000.
%Textor, C., Schulz, M., Guibert, S., Kinne, S., Balkanski, Y., Bauer, S., %Berntsen, T., Berglen, T., Boucher, O., Chin, M., Dentener, F., Diehl, T., %Easter, R., Feichter, H., Fillmore, D., Ghan, S., Ginoux, P., Gong, S., %Grini, A., Hendricks, J., Horowitz, L., Huang, P., Isaksen, I., Iversen, T., %Kloster, S., Koch, D., KirkevÃ¥g, A., Kristjansson, J. E., Krol, M., %Lauer, A., Lamarque, J. F., Liu, X., Montanaro, V., Myhre, G., Penner, J., %Pitari, G., Reddy, S., Seland, Ø., Stier, P., Takemura, T., and Tie, X.: %Analysis and quantification of the diversities of aerosol life cycles within %AeroCom, Atmos. Chem. Phys., 6, 1777-1813, 2006. Textor, C., Schulz, M., Guibert, S., Kinne, S., Balkanski, Y., Bauer, S., Berntsen, T., Berglen, T., Boucher, O., Chin, M., Dentener, F., Diehl, T., Easter, R., Feichter, H., Fillmore, D., Ghan, S., Ginoux, P., Gong, S., Grini, A., Hendricks, J., Horowitz, L., Huang, P., Isaksen, I., Iversen, I., Kloster, S., Koch, D., Kirkevåg, A., Kristjansson, J. E., Krol, M., Lauer, A., Lamarque, J. F., Liu, X., Montanaro, V., Myhre, G., Penner, J., Pitari, G., Reddy, S., Seland, Ø., Stier, P., Takemura, T., and Tie, X.: Analysis and quantification of the diversities of aerosol life cycles within AeroCom, Atmos. Chem. Phys., 6, 1777–1813, http://dx.doi.org/10.5194/acp-6-1777-2006doi:10.5194/acp-6-1777-2006, 2006.
van der Werf, G. R., Randerson, J. T., Giglio, L., Collatz, C. J., Kasibhatla, P. S., and Arellano Jr., A. F.: Interannual variability in global biomass burning emissions from 1997 to 2004, Atmos. Chem. Phys., 6, 3421–3441, 2006.
Wild, O., Prather, M. J., and Akimoto, H.: Indirect long-term global radiative cooling from NO<sub>x</sub> emissions, Geophys. Res. Let., 28, 1719–1722, 2001.
Yu, H., Kaufman, Y. J., Chin, M., Feingold, G., Remer, L. A., Anderson, T. L., Balkanski, Y., Bellouin, N., Boucher, O., Christopher, S., DeCola, P., Kahn, R., Koch, D., Loeb, N., Reddy, M. S., Schulz, M., Takemura, T., and Zhou, M.: A review of measurement-based assessments of the aerosol direct radiative effect and forcing, Atmos. Chem. Phys., 6, 613–666, http://dx.doi.org/10.5194/acp-6-613-2006doi:10.5194/acp-6-613-2006, 2006.