ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-11-7119-2011 Microphysical, macrophysical and radiative signatures of volcanic aerosols in trade wind cumulus observed by the A-Train Yuan T. 1 2 Remer L. A. 2 Yu H. 2 3 Joint Center for Earth Systems Technology, University of Maryland, Baltimore County, Baltimore, MD, USA Laboratory for Atmospheres, NASA Goddard Space Flight Center, Greenbelt, MD, USA Earth System Science Interdisciplinary Center, University of Maryland, College Park, MD, USA 21 07 2011 11 14 7119 7132 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/11/7119/2011/acp-11-7119-2011.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/11/7119/2011/acp-11-7119-2011.pdf

Increased aerosol concentrations can raise planetary albedo not only by reflecting sunlight and increasing cloud albedo, but also by changing cloud amount. However, detecting aerosol effect on cloud amount has been elusive to both observations and modeling due to potential buffering mechanisms and convolution of meteorology. Here through a natural experiment provided by long-term degassing of a low-lying volcano and use of A-Train satellite observations, we show modifications of trade cumulus cloud fields including decreased droplet size, decreased precipitation efficiency and increased cloud amount are associated with volcanic aerosols. In addition we find significantly higher cloud tops for polluted clouds. We demonstrate that the observed microphysical and macrophysical changes cannot be explained by synoptic meteorology or the orographic effect of the Hawaiian Islands. The "total shortwave aerosol forcin", resulting from direct and indirect forcings including both cloud albedo and cloud amount, is almost an order of magnitude higher than aerosol direct forcing alone. Furthermore, the precipitation reduction associated with enhanced aerosol leads to large changes in the energetics of air-sea exchange and trade wind boundary layer. Our results represent the first observational evidence of large-scale increase of cloud amount due to aerosols in a trade cumulus regime, which can be used to constrain the representation of aerosol-cloud interactions in climate models. The findings also have implications for volcano-climate interactions and climate mitigation research.

 References Ackerman, A. S., Toon, O. B., Stevens, D. E., Heymsfield, A. J., Ramanathan, V., and Welton, E. J.: Reduction of tropical cloudiness by soot, Science, 288, 5468, 1042–1047, 2000. Ackerman, A. S., Kirkpatrick, M. P., Stevens, D. E., and Toon, O. B.: The impact of humidity above stratiform clouds on indirect aerosol climate forcing, Nature, 432, 7020, http://dx.doi.org/10.1038/nature03174doi:10.1038/nature03174, 2004. Albrecht, B. A.: Aerosols, Cloud Microphysics, and Fractional Cloudiness, Science, 245, 4923, http://dx.doi.org/10.1126/science.245.4923.1227doi:10.1126/science.245.4923.1227, 1989. Andreae, M. O., Rosenfeld, D., Artaxo, P., Costa, A. A., Frank, G. P., Longo, K. M., and Silva-Dias, M. A. F.: Smoking rain clouds over the Amazon. Science, 303, 5662, 1337–1342, 2004. Anderson, T. L., Charlson, R. J., Schwartz, S. E., Knutti, R., Boucher, O., Rodhe, H., and Heintzenberg, J.: Climate forcing by aerosols –a hazy picture, Science, 300, 5622, 1103–1104, 2003. Betts, A. K. and Albrecht, B. A.: Conserved variable analysis of the convective boundary-layer thermodynamic structure over the Tropical Ocean, J. Atmos. Sci., 44(1), 83–99, 1987. Brenguier, J. L., Pawlowska, H., and Schuller, L.: Cloud microphysical and radiative properties for parameterization and satellite monitoring of the indirect effect of aerosol on climate, J. Geophys. Res.-Atmos., 108(D15), 8632, http://dx.doi.org/10.1029/2002JD002682doi:10.1029/2002JD002682, 2003. Bretherton, C. S., Blossey, P. N., and Uchida, J., Cloud droplet sedimentation, entrainment efficiency, and subtropical stratocumulus albedo, Geophys. Res. Lett., 34(3), L03813, http://dx.doi.org/10.1029/2006GL027648doi:10.1029/2006GL027648, 2007. Charlson, R. J., Ackerman, A. S., Bender, F. A., Anderson, T. L., and Liu, Z., On the climate forcing consequences of the albedo continuum between cloudy and clear air, Tellus B, 59(4), 715–727, http://dx.doi.org/10.1111/j.1600-0889.2007.00297.xdoi:10.1111/j.1600-0889.2007.00297.x, 2007. Christensen, M., and Stephens, G., Microphysical and macrophysical responses of marine stratocumulus polluted by underlying ships: Evidence of cloud deepening, J. Geophys. Res.-Atmos., 116, D03201, http://dx.doi.org/10.1029/2010JD014638doi:10.1029/2010JD014638, 2011. Dey, S., Di Girolamo, L., Zhao, G., Jones, A. L., and Mcfarquhar, G.: Satellite-observed relationships between aerosol and trade-wind cumulus cloud properties over the Indian Ocean, Geophys Res Lett, 38, L01804, http://dx.doi.org/10.1029/2010GL045588doi:10.1029/2010GL045588, 2011. Feingold, G. and Siebert, H.: Cloud-aerosol interactions from the micro to the cloud scale, Clouds in Perturbed Climate system: their relationship to energy balance, atmospheric dynamics and precipitation, MIT Press, Cambridge, MA, USA, 2009. Feingold, G., Kreidenweis, S. M., Stevens, B., and Cotton, W. R.: Numerical simulations of stratocumulus processing of cloud condensation nuclei through collision-coalescence, J. Geophys. Res. Atmos., 101(D16), 21391–21402, 1996. Feingold, G., Koren, I., Wang, H., Xue, H., and Brewer, W. A.: Precipitation-generated oscillations in open cellular cloud fields, Nature, 466, 7308, http://dx.doi.org/10.1038/nature09314doi:10.1038/nature09314, 2010. Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Dorland, R. V.: Changes in Atmospheric Constituents and in Radiative Forcing, The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press, Cambridge, UK and New York, USA, 2007. Gasso, S.: Satellite observations of the impact of weak volcanic activity on marine clouds, J. Geophys. Res. Atmos., 113(D14), D14S19, http://dx.doi.org/10.1029/2007JD009106doi:10.1029/2007JD009106, 2008. Hafner, J. and Xie, S. P.: Far-field simulation of the Hawaiian wake: Sea surface temperature and orographic effects, J Atmos Sci, 60(24), 3021–3032, 2003. Haynes, J. M., L'ecuyer, T. S., Stephens, G. L., Miller, S. D., Mitrescu, C., Wood, N. B., and Tanelli, S.: Rainfall retrieval over the ocean with spaceborne W-band radar. J. Geophys. Res. Atmos., 114, D00A22, http://dx.doi.org/10.1029/2008JD009973doi:10.1029/2008JD009973, 2009. Haywood, J., Donner, L. J., Jones, A., and Golaz, J.: Global Indirect Radiative Forcing Caused by Aerosols IPCC (2007) and Beyond, Clouds in the perturbed climate system: their relationship to energy balance, atmospheric dynamics and precipitation, MIT press, Cambridge, MA, USA, 2009. Hegerl, G. C. and Solomon, S.: Risks of Climate Engineering. Science, 325, 5943, 955–956, http://dx.doi.org/10.1126/science.1178530doi:10.1126/science.1178530, 2009. Heymsfield, A. J. and Mcfarquhar, G. M., Microphysics of INDOEX clean and polluted trade cumulus clouds, J. Geophys. Res. Atmos., 106(D22), 28653–28673, 2001. Jiang, H., Feingold, G., and Koren, I.: Effect of aerosol on trade cumulus cloud morphology, J. Geophys. Res. Atmos., 114, D11209, http://dx.doi.org/10.1029/2009JD011750doi:10.1029/2009JD011750, 2009. Jones, A., Haywood, J., and Boucher, O.: Climate impacts of geoengineering marine stratocumulus clouds, J. Geophys. Res. Atmos., 114, D10106, http://dx.doi.org/10.1029/2008JD011450doi:10.1029/2008JD011450, 2009. Kaufman, Y. J. and Koren, I., Smoke and pollution aerosol effect on cloud cover, Science, 313, 5787, http://dx.doi.org/10.1126/science.1126232doi:10.1126/science.1126232, 2006. Kidd, C. and Mcgregor, G.: Observation and characterisation of rainfall over Hawaii and surrounding region from the Tropical Rainfall Measuring Mission, Int. J. Climatol., 27(4), 541–553, http://dx.doi.org/10.1002/joc.1414doi:10.1002/joc.1414, 2007. Koren, I., Kaufman, Y. J., Remer, L. A., and Martins, J. V.: Measurement of the effect of Amazon smoke on inhibition of cloud formation, Science, 303, 1342–1345, 2004. Koren, I., Kaufman, Y. J., Rosenfeld, D., Remer, L. A., and Rudich, Y.: Aerosol invigoration and restructuring of Atlantic convective clouds, Geophys. Res. Lett., 32(14), L14828, http://dx.doi.org/10.1029/2005GL023187doi:10.1029/2005GL023187, 2005. Koren, I., Remer, L. A., Kaufman, Y. J., Rudich, Y., and Martins, J. V.: On the twilight zone between clouds and aerosols, Geophys. Res. Lett., 34(8), L08805, http://dx.doi.org/10.1029/2007GL029253doi:10.1029/2007GL029253, 2007. Koren, I., Oreopoulos, L., Feingold, G., Remer, L. A., and Altaratz, O.: How small is a small cloud? Atmos. Chem. Phys., 8, 3855–3864, http://dx.doi.org/10.5194/acp-8-3855-2008doi:10.5194/acp-8-3855-2008, 2008. Koren, I., Feingold, G., Jiang, H., and Altaratz, O.: Aerosol effects on the inter-cloud region of a small cumulus cloud field, Geophys. Res. Lett., 36, L14805, http://dx.doi.org/10.1029/2009GL037424doi:10.1029/2009GL037424, 2009. Latham, J., Rasch, P., Chen, C., Kettles, L., Gadian, A., Gettelman, A., Morrison, H., Bower, K., and Choularton, T.: Global temperature stabilization via controlled albedo enhancement of low-level maritime clouds, Philos. T. R. Soc. A, 366, 3969–3987, http://dx.doi.org/10.1098/rsta.2008.0137doi:10.1098/rsta.2008.0137, 2008. Loeb, N. G. and Schuster, G. L.: An observational study of the relationship between cloud, aerosol and meteorology in broken low-level cloud conditions. J. Geophys. Res. Atmos., 113(D14), D14214, http://dx.doi.org/10.1029/2007JD009763doi:10.1029/2007JD009763, 2008. Lohmann, U., Koren, I., and Kaufman, Y. J.: Disentangling the role of microphysical and dynamical effects in determining cloud properties over the Atlantic, Geophys. Res. Lett., 33(9), L09802, http://dx.doi.org/10.1029/2005GL024625doi:10.1029/2005GL024625, 2006. Lu, M. L., and Seinfeld, J. H.: Study of the aerosol indirect effect by large-eddy simulation of marine stratocumulus, J. Atmos. Sci., 62(11), 3909–3932, 2005. Marshak, A., Platnick, S., Varnai, T., Wen, G. Y., and Cahalan, R. F.: Impact of three-dimensional radiative effects on satellite retrievals of cloud droplet sizes, J. Geophys. Res. Atmos., 111(D9), D09207, http://dx.doi.org/10.1029/2005JD006686doi:10.1029/2005JD006686, 2006. Mauger, G. S. and Norris, J. R.: Meteorological bias in satellite estimates of aerosol-cloud relationships, Geophys. Res. Lett., 34(16), L16824, http://dx.doi.org/10.1029/2007GL029952doi:10.1029/2007GL029952, 2007. Mccormic, R. and Ludwig, J. H.: Climate modification by atmospheric aerosols, Science, 156, 1358–1359, 1967. Mcfarquhar, G. M., Platnick, S., Di Girolamo, L., Wang, H. K., Wind, G., and Zhao, G. Y.: Trade wind cumuli statistics in clean and polluted air over the Indian Ocean from in situ and remote sensing measurements, Geophys. Res. Lett., 31(21), L21105, http://dx.doi.org/10.1029/2004GL020412doi:10.1029/2004GL020412, 2004. Nakajima, T., Higurashi, A., Kawamoto, K., and Penner, J. E.: A possible correlation between satellite-derived cloud and aerosol microphysical parameters, Geophys. Res. Lett., 28(7), 1171–1174, 2001. Norris, J. R.:, Has northern Indian Ocean cloud cover changed due to increasing anthropogenic aerosol?, Geophys. Res. Lett., 28(17), 3271–3274, 2001. Norris, J. R. and Slingo, A.: Trends in observed cloudiness and Earth's radiation budget: what do we not know and what do we need to know?. Clouds in the Perturbed Climate system: their relationship to energy balance, atmospheric dynamics and precipitation, MIT Press, Cambridge, MA, USA, 2009. Pincus, R. and Baker, M. B.: Eeffect of precipitation on the albedo susceptibility of clouds in the marine boundary-layer, Nature, 372, 250–252, 1994. Platnick, S. and Oreopoulos, L.: Radiative susceptibility of cloudy atmospheres to droplet number perturbations: 1. Theoretical analysis and examples from MODIS, J. Geophys. Res. Atmos., 113(D14), D14S20, http://dx.doi.org/10.1029/2007JD009654doi:10.1029/2007JD009654, 2008. Platnick, S., King, M. D., Ackerman, S. A., Menzel, W. P., Baum, B. A., Riedi, J. C., and Frey, R. A.: The MODIS cloud products: Algorithms and examples from Terra, IEEE Trans. Geosci. Remote Sens., 41(2), 459–473, http://dx.doi.org/10.1109/TGRS.2002.808301doi:10.1109/TGRS.2002.808301, 2003. Quaas, J., Ming, Y., Menon, S., Takemura, T., Wang, M., Penner, J. E., Gettelman, A., Lohmann, U., Bellouin, N., Boucher, O., Sayer, A. M., Thomas, G. E., Mccomiskey, A., Feingold, G., Hoose, C., Kristjansson, J. E., Liu, X., Balkanski, Y., Donner, L. J., Ginoux, P. A., Stier, P., Grandey, B., Feichter, J., Sednev, I., Bauer, S. E., Koch, D., Grainger, R. G., Kirkevag, A., Iversen, T., Seland, O., Easter, R., Ghan, S. J., Rasch, P. J., Morrison, H., Lamarque, J., Iacono, M. J., Kinne, S., and Schulz, M.: Aerosol indirect effects - general circulation model intercomparison and evaluation with satellite data, Atmos. Chem. Phys., 9, 8697–8717, http://dx.doi.org/10.5194/acp-9-8697-2009doi:10.5194/acp-9-8697-2009, 2009. Rauber, R. M., Stevens, B., Ochs, H. T., Knight, C., Albrecht, B. A., Blyth, A. M., Fairall, C. W., Jensen, J. B., Lasher-Trapp, S. G., Mayol-Bracero, O. L., Vali, G., Anderson, J. R., Baker, B. A., Bandy, A. R., Burnet, E., Brenguier, J. L., Brewer, W. A., Brown, P. R. A., Chuang, P., Cotton, W. R., Girolamo, L. D., Geerts, B., Gerber, H., Goke, S., Gomes, L., Heikes, B. G., Hudson, J. G., Kollias, P., Lawson, R. P., Krueger, S. K., Lenschow, D. H., Nuijens, L., O'sullivan, D. W., Rilling, R. A., Rogers, D. C., Siebesma, A. P., Snodgrass, E., Stith, J. L., Thornton, D. C., Tucker, S., Twohy, C. H., and Zuidema, P.: Rain in shallow cumulus over the ocean – The RICO campaign, B. Am. Meteorol. Soc., 88(12), 1912–1928, http://dx.doi.org/10.1175/BAMS-88-12-1912doi:10.1175/BAMS-88-12-1912, 2007. Remer, L. A. and Kaufman, Y. J.: Aerosol direct radiative effect at the top of the atmosphere over cloud free ocean derived from four years of MODIS data, Atmos. Chem. Phys., 6, 237–253, http://dx.doi.org/10.5194/acp-6-237-2006doi:10.5194/acp-6-237-2006, 2006. Remer, L. A., Kaufman, Y. J., Tanre, D., Mattoo, S., Chu, D. A., Martins, J. V., Li, R. R., Ichoku, C., Levy, R. C., Kleidman, R. G., Eck, T. F., Vermote, E., and Holben, B. N.: The MODIS aerosol algorithm, products, and validation, J. Atmos. Sci., 62(4), 947–973, 2005. Riehl, H., Yeh, T. C., Malkus, J. S., and Laseur, N. E.: The north-east trade of the Pacific Ocean, Q. J. Roy. Meteorol. Soc., 77, 598–626, 1951. Robock, A.: Volcanic eruptions and climate, Rev. Geophys., 38(2), 191–219, 2000. Robock, A., Bunzl, M., Kravitz, B., and Stenchikov, G. L.: A Test for Geoengineering?, Science, 327, 530–531, http://dx.doi.org/10.1126/science.1186237doi:10.1126/science.1186237, 2010. Rosenfeld, D.: TRMM observed first direct evidence of smoke from forest fires inhibiting rainfall, Geophys. Res. Lett., 26(20), 3105–3108, 1999. Rosenfeld, D.: Suppression of rain and snow by urban and industrial air pollution, Science, 287, 1793–1796, 2000. Snodgrass, E. R., Di Girolamo, L., and Rauber, R. M.: Precipitation Characteristics of Trade Wind Clouds during RICO Derived from Radar, Satellite, and Aircraft Measurements, J. Appl. Meteorol. Clim., 48(3), 464–483, http://dx.doi.org/10.1175/2008JAMC1946.1doi:10.1175/2008JAMC1946.1, 2009. Stephens, G. L., Vane, D. G., Boain, R. J., Mace, G. G., Sassen, K., Wang, Z. E., Illingworth, A. J., O'connor, E. J., Rossow, W. B., Durden, S. L., Miller, S. D., Austin, R. T., Benedetti, A., and Mitrescu, C.: The cloudsat mission and the a-train – A new dimension of space-based observations of clouds and precipitation. B. Am. Meteorol. Soc., 83(12), 1771–1790, http://dx.doi.org/10.1175/BAMS-83-12-1771doi:10.1175/BAMS-83-12-1771, 2002. Stevens, B. and Feingold, G.: Untangling aerosol effects on clouds and precipitation in a buffered system, Nature, 461, 607–613, http://dx.doi.org/10.1038/nature08281doi:10.1038/nature08281, 2009. Stevens, B., Cotton, W. R., Feingold, G., and Moeng, C. H., Large-eddy simulations of strongly precipitating, shallow, stratocumulus-topped boundary layers, J. Atmos. Sci., 55(24), 3616–3638, 1998. Twomey, S.: Influence of pollution on shortwave albedo of clouds, J. Atmos. Sci., 34(7), 1149–1152, 1977. Wen, G. Y., Marshak, A., and Cahalan, R. F.: Impact of 3-D clouds on clear-sky reflectance and aerosol retrieval in a biomass burning region of Brazil, IEEE Geosci. Remote Sens., 3, 169–172, http://dx.doi.org/10.1109/LGRS.2005.861386doi:10.1109/LGRS.2005.861386, 2006. Wielicki, B. A., Barkstrom, B. R., Harrison, E. F., Lee, R. B., Smith, G. L., and Cooper, J. E.: Clouds and the earth's radiant energy system (CERES): An earth observing system experiment, B. Am. Meteorol. Soc., 77(5), 853–868, 1996. Wilks, D. S.: Statistical Methods in the Atmospheric Sciences, ACADEMIC PRESS, Maryland Heights, MO, 2005. Wood, R.: Cancellation of aerosol indirect effects in marine stratocumulus through cloud thinning. J Atmos Sci, 64(7), 2657–2669, http://dx.doi.org/10.1175/JAS3942.1doi:10.1175/JAS3942.1, 2007. Wyant, M. C., Bretherton, C. S., Rand, H. A., and Stevens, D. E.: Numerical simulations and a conceptual model of the stratocumulus to trade cumulus transition, J. Atmos. Sci., 54(1), 168–192, 1997. Xie, S. P., Liu, W. T., Liu, Q. Y., and Nonaka, M.: Far-reaching effects of the Hawaiian islands on the Pacific Ocean-atmosphere system, Science, 292, 2057–2060, 2001. Xue, H., Feingold, G., and Stevens, B.: Aerosol effects on clouds, precipitation, and the organization of shallow cumulus convection, J. Atmos. Sci., 65(2), 392–406, http://dx.doi.org/10.1175/2007JAS2428.1doi:10.1175/2007JAS2428.1, 2008. Xue, H. W. and Feingold, G.: Large-eddy simulations of trade wind cumuli: Investigation of aerosol indirect effects, J. Atmos. Sci., 63(6), 1605–1622, 2006. Yuan, T., Li, Z., Zhang, R., and Fan, J.: Increase of cloud droplet size with aerosol optical depth: An observation and modeling study, J. Geophys. Res. Atmos., 113(D4), D04201, http://dx.doi.org/10.1029/2007JD008632doi:10.1029/2007JD008632, 2008. Yuan, T., Remer, L. A., Pickering, K. E., and Yu, H.: Observational evidence of aerosol enhancement of lightning activity and convective invigoration, Geophys. Res. Lett., 38, L04701, http://dx.doi.org/10.1029/2010GL046052doi:10.1029/2010GL046052, 2011. Zhao, G. and Di Girolamo, L.: Statistics on the macrophysical properties of trade wind cumuli over the tropical western Atlantic, J. Geophys. Res. Atmos., 112, D10204, http://dx.doi.org/10.1029/2006JD007371doi:10.1029/2006JD007371, 2007.